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Filtration Efficiencies of Nanoscale Aerosol by Cloth Mask Materials Used to Slow the Spread of SARS-CoV-2

  • Christopher D. Zangmeister*
    Christopher D. Zangmeister
    Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
    *Email: [email protected]. Phone: (301) 975-8709.
    More by Christopher D. Zangmeister
    Orcidhttp://orcid.org/0000-0002-6026-9293
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  • James G. Radney
    James G. Radney
    Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
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    Orcidhttp://orcid.org/0000-0001-7324-8769
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  • Edward P. Vicenzi
    Edward P. Vicenzi
    Museum Conservation Institute, Smithsonian Institution, Suitland, Maryland 20746, United States
    Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
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  • , and 
  • Jamie L. Weaver
    Jamie L. Weaver
    Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
    Museum Conservation Institute, Smithsonian Institution, Suitland, Maryland 20746, United States
    More by Jamie L. Weaver
    Orcidhttp://orcid.org/0000-0002-6762-0568
Cite this: ACS Nano 2020, 14, 7, 9188–9200
Publication Date (Web):June 25, 2020
https://doi.org/10.1021/acsnano.0c05025
This article not subject to U.S. Copyright. Published 2020 by American Chemical Society
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Abstract

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Filtration efficiency (FE), differential pressure (ΔP), quality factor (QF), and construction parameters were measured for 32 cloth materials (14 cotton, 1 wool, 9 synthetic, 4 synthetic blends, and 4 synthetic/cotton blends) used in cloth masks intended for protection from the SARS-CoV-2 virus (diameter 100 ± 10 nm). Seven polypropylene-based fiber filter materials were also measured including surgical masks and N95 respirators. Additional measurements were performed on both multilayered and mixed-material samples of natural, synthetic, or natural-synthetic blends to mimic cloth mask construction methods. Materials were microimaged and tested against size selected NaCl aerosol with particle mobility diameters between 50 and 825 nm. Three of the top five best performing samples were woven 100% cotton with high to moderate yarn counts, and the other two were woven synthetics of moderate yarn counts. In contrast to recently published studies, samples utilizing mixed materials did not exhibit a significant difference in the measured FE when compared to the product of the individual FE for the components. The FE and ΔP increased monotonically with the number of cloth layers for a lightweight flannel, suggesting that multilayered cloth masks may offer increased protection from nanometer-sized aerosol with a maximum FE dictated by breathability (i.e., ΔP).

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This article is made available via the ACS COVID-19 subset for unrestricted RESEARCH re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemic.

It has been recognized that the global spread of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has limited the supply of medical masks and particulate filtering facepiece respirators (e.g., N95), so it has been recommended that their use be restricted to healthcare settings. (1) As of this writing, the World Health Organization (WHO) and the United States Centers for Disease Control and Prevention (US CDC) suggest that cloth masks be used in nonmedical settings to reduce the transmission of SARS-CoV-2. (2,3) The majority of states in the United States and more than 130 nations, corresponding to over 75% of the global population, have issued official guidelines requiring or recommending the wearing of masks in public locations to mitigate the spread of COVID-19, the disease caused by SARS-CoV-2. Thus, nonmedical use of facial coverings will likely consist of masks made from a variety of fibrous cloth materials utilizing a range of designs and construction techniques. The WHO has stated the need for rapid dissemination of research investigating the performance of relevant mask parameters, for example, material, design, and construction, for reducing exposure to micrometer-sized droplets and nanometer-sized aerosol particles at size ranges relevant to the virus (90 nm diameter core with ≈20 nm spike proteins). (1,3,4) Particle measurements from hosptials in Wuhan, China demonstrated that viable COVID-19 virus likely exists in particles with diameters between 250 nm and 500 nm. (5)
Facemasks can provide two modes of protection: (6) (1) by protecting the localized population from an infected mask wearer by trapping expelled virus-laden atomized material (droplets or aerosol) and (2) by protecting the mask wearer from ambient virus-laden atomized material by filtering inhaled air. (7) This reduces the risk of both direct and indirect viral exposure, respectively, thereby decreasing the probability of infection. (6)
Prior research into cloth masks follows the history of infectious diseases spread by droplets or aerosol and dates back to the 1918–1919 influenza pandemic. (8,9) After that time, the publication record on the utility of cloth masks is sparse, and most research has focused on the effectiveness of single use masks available in many developed countries for healthcare or other occupational settings. (10−16) The prior research shows that cloth materials offer limited protection from particles in the size regime of SARS-COV2. (10−12)
When particles interact with a filter fiber, it is generally accepted that they are “collected” by a fiber and retained through van Der Waals forces. (17) For small particles, Brownian motion increases the probability a particle will interact with a filter fiber. At larger sizes, particles can be intercepted by a fiber when they are within one particle radius. When particle inertia becomes sufficiently high, the particle may no longer follow a flowing gas streamline resulting in a higher probability of inertially impacting a fiber. Electrostatic deposition, occurring due to a charge difference between a fiber and a particle, can also be important in some materials. Collectively, the sum of these efficiencies, diffusion (ED), interception (ER), impaction (EI), and electrostatic deposition (EB), yield the single fiber efficiency (EF = ED + ER + EI + EB). The reader is directed to the seminal works by Brown, (18) Emi, (19) Fuchs, (20,21) and Liu (22) for detailed descriptions of filtration theory.
The filtration efficiency (FE) is a common metric for reporting particle capture efficiency of material and is related to EF through (18−23)
(1)
where α, L, and Df are the material porosity (i.e., packing density), filter thickness, and fiber or yarn diameter, respectively. The FE can be quantified by measuring the upstream and downstream (NU and ND, respectively) number density of particles per volume of air (particles cm–3) where particles ND passed through the filter and particles NU were incident on the filter (see Figure S1 of the Supporting Information), and the difference between NU and ND represents the particles captured by the filter. FE is reported as a percentage (by multiplying eq 1 by 100) and is a function of the particle diameter (D), the flow rate through the filter, and the filter medium. (10−16,24,25)
The variability of test methods (mask materials vs fitted mask on human-scale forms vs standard mask testbed measurements) and the broad range of materials tested make direct quantitative comparability between published studies highly challenging. (10−16) In studies before 2020, the published FE of cotton-based fabrics was 5% to 60% when tested against an NaCl aerosol with 20 nm ≤ D ≤ 1000 nm, 10% for spherical 100 nm latex particles, and <10% for 100 nm diesel soot. (10−12) Generally, the published FE of cloth filter media is much lower when compared to facepiece respirators that are regulated for use in healthcare and other professional settings; for example, the FFP2 (EU standard, EN 149–2001) or the N95 (USA, NIOSH-42C FR84), which are rigorously tested to ensure FE ≥ 94% and FE ≥ 95%, respectively, for 300 nm D NaCl. (26,27) Notably, a recently published study suggests that masks from cloth filter media can be constructed that may afford better protection for the wearer than an N95 respirator for particles between 10 nm and 200 nm in size due to an enhancement in EB by specific types of cloth arranged in a multilayered configuration. (15)
The study reported here aims to aid in the call for research testing the performance of cloth-based media that are relevant for mask use. (3) The FE and differential pressure (ΔP, Pa), which is related to breathability, were measured for 32 relevant cloth materials (14 cotton, 1 wool, 9 synthetic, 4 synthetic blends, and 4 synthetic/cotton blends) that may be used in facemasks. The FE and ΔP were measured under controlled laboratory conditions utilizing size selected NaCl aerosol with particle mobility diameters (Dm) between 50 and 825 nm, a size regime relevant for the removal of SARS-CoV-2 particles, (6,28) and in accordance to standard established filter testing protocols, Parts 3 and 5 of EN 1822 and ISO 29463, using size selected charged and neutralized aerosol, respectively. For comparison, the FE and ΔP of 7 polypropylene containing materials (2 surgical facemasks, an N95 filter, N95 fabric, a high- and low-density medical wrap, and a purported HEPA vacuum bag), 2 papers (coffee filter and paper towels), and 4-layered samples of different materials were also measured. The samples in this study were systematically chosen and characterized by their composition, yarn count, weave type (which has been relatively understudied), (29) and mass with the goal of establishing a relationship between these parameters and measured FE and ΔP when tested against nanometer-sized aerosol under well controlled laboratory conditions using established filter testing protocols.

Results and Discussion

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Both nanometer-sized aerosol particles and micrometer-sized droplets can be captured by a filter. (17) The FE is a function of Dm, Df, fiber packing density, and flow rate. (25) Freshly generated particles may be highly charged but immediately start to neutralize after emission. (30) Ambient aerosols are expected to have a net neutral average charge that follows a Boltzmann distribution after <100 min aloft (25) (note, lifetimes of nanoparticles span hours to days over this size range). (31) Differences in the charge state or distribution of charges of the aerosol may impact the measured FE with EB typically enhancing FE. (32)
The distribution of particle sizes filtered by a material can be broadened by using random arrays or layered structures containing a distribution of fiber diameters. (23,33) This has allowed for the development of filtration media with excellent FE across a broad range of Dm at reasonable ΔP (e.g., the N95 mask and HEPA filters, see Figure 1B1,2) and may also give insight into the design and use of cloth materials for facemasks for the capture of virus-laden aerosols. Therefore, an understanding of the filter structure (including weave structure, yarn count, and yarn mass) and material composition (natural, synthetic, or blended materials) may be important for the FE of cloth materials and may provide a deeper understanding in the complex parameter space that influences the FE of cloth mask materials.

Figure 1

Figure 1. Transmitted light imagery of nonwoven and woven face mask materials. (A1–3) Outer, intermediate, and inner layers of a N95 mask showing randomly oriented spun-bond (A1) and melt-blown (A2 and A3) synthetic fibers. (34) (B1,2) Outer and inner surfaces of poplin weave cotton fibers in lightweight flannel (sample Cotton 10). Note: Transmitted light grayscale intensities have been inverted so fibers appear lighter relative to voids; all scale bars represent 1 mm with subsections of 200 μm in length.

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There have been several suggestions that FE may be related to textile parameters. Recently, Konda et al. (2020) (15) indicated an increase in FE as a function of higher yarn count (described as TPI in the cited article and summarized in their Figure 3, and which herein will be discussed as yarns inch–2 unless otherwise noted; 2.54 cm = 1 in). Other studies have suggested that the cover factor, defined as the sum of the number of yarns per unit length to the square root of the yarn count for the warp and weft directions (see Supporting Information for definitions), is also related to a fabric’s filtration level (but not FE directly). (35) The cover factor indicates the extent to which the area of a fabric is covered by one set of yarns, and a fabric with a high cover factor would have a low density of open space relative to fabric material for a given area. Cover factor is differentiated from packing density, as cover factor assumes the yarns are solid and nonporous, thus underestimating a materials porosity. Other parameters that may play a role are yarn mass, fabric texture, and fabric composition. Past studies at the National Bureau of Standards (NBS, currently the National Institute of Standards and Technology, NIST) indicated relationships between yarn count, fabric mass, and weave type with permeability to air, which is related to the ΔP and the level of breathability through the material. (29)
Electrostatics, as discussed by Konda et al. (2020) (15) and Zhao et al. (2020), (36) may be another important parameter and are addressed in this investigation by studying the impact of particle and cloth charge (see further). A theoretical model of fabric electrostatics was proposed by Alekseeva et al. (2007) (37) and suggested that fabrics can behave like a capacitor, collecting electric charge in the gaps (pores) in fibers of the fabric. The specific properties are potentially dependent on fiber composition, weave type and tightness (related to cover factor), production and processing methods, and can be influenced by atmospheric conditions (humidity, pressure, and temperature). (38) The electrostatics of cloth materials are more commonly (although not always) discussed for synthetic as opposed to natural fibers. (39)
The FE values of 41 samples, 32 cloth materials (14 cotton, 1 wool, 9 synthetic, 4 synthetic blends, 4 synthetic/cotton blends), 2 paper materials, and 7 polypropylene-based fiber filter materials, were measured at 15 equally log-spaced mobility diameters (Dm) resulting in Dm spanning 50 nm ≤ Dm ≤ 825 nm. Particles were charge neutralized (as recommended by Parts 3 and 5 of the EN 1822 mask filtration protocol) using a soft X-ray source and size selected by a differential mobility analyzer. (27) For comparison, seven of the samples were reneutralized after size selection in accordance with the ISO 29643 filter testing standard. Particle number densities upstream (NU) and downstream (ND) of the sample were recorded by condensation particle counters (CPC) for 30 s at 1 Hz at each Dm. These data were averaged, and 1σ standard deviations were calculated at each Dm bin. Measured 1σ standard deviations in N were ≈2.5% with a CPC accuracy of ≈3% for N < 2 × 104 cm–3 (independently calibrated by optical methods), (40) and ≈2% day-to-day variability in FE for the same sample and ∼1% sample-to-sample variability in FE, resulting in an assumed 5% combined uncertainty for FE; see Figures S13 and S28 for day-to-day and sample-to-sample variabilities, respectively. The ND was scaled based upon the CPC counting mode (single particle versus photometric; see Figure S2 and corresponding discussion in the Supporting Information), and the FE was calculated from eq 1.
Representative FE values as a function of Dm are shown in Figure 2 for four of the tested samples (an N95 respirator, the base fabric that is used to make an N95 respirator, a surgical mask, and a 65%/35% cotton/polyester twill polyester/cotton blend 3, twill weave, 229 yarns inch–2). Importantly, the measured data capture the FE under conditions where leaks are absent. The aerosol after size selection had moderate net charge (q, where +1 ≤ q ≤ ∼ + 4 due to charge neutralization prior to the measurement). (41) The impact of particle charge on FE was tested by also measuring the FE of 7 samples that were reneutralized after size selection (dashed light lines and squares in Figure 2 and blue traces in Figures S21, S36, S39, S49, S50, S51, and S52). The measured data indicate that particle charge does not impact FE of the measured cloth materials. In addition, the FE of polyester/cotton blend 3 was quantified by passing the size selected aerosol through an aerosol particle mass analyzer (APM) and subsequently reneutralizing (olive triangles in Figures 2 and S39). The tandem DMA-APM effectively removes the presence of particles with q > + 1 that may exit the DMA. (42,43) With the exception of the surgical mask that uses polypropylene layers for filtration, aerosol reneutralization (and mass selection) did not affect FE (all values were within 1σ uncertainty), see Figure 2, suggesting that EB is not significant for these cloth materials under current conditions and is in agreement with previous observations. (10)

Figure 2

Figure 2. Measured filtration efficiency (FE) as a function of particle mobility diameter (Dm) for an N95 respirator (black), the N95 base fabric (orange), a surgical mask (pink), and a twill (blue). The solid bold lines and circles represent the base sample, while the dashed light lines and squares correspond to the reneutralized samples. Olive triangles correspond to the twill FE measured with an aerosol particle mass analyzer and reneutralization. Uncertainties in FE are ±5%. See discussion in text. Corresponding distributions of NU and ND can be found in Section S3 of the Supporting Information.

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The FE values presented here are likely higher than typically measured on a mask testing device as required for regulatory compliance (e.g., US 42 CFR 84 or EN143) and should be interpreted as the maximum expected FE of the material for mechanical processes (ED, ER, and EI). Unless otherwise noted, the reported values are shown for aerosols that were not reneutralized after size selection (see additional sample FE curves of reneutralized aerosol in Section S3 of the Supporting Information).
Previous studies have reported values of FEmin and the most penetrating particle size (MPPS, i.e., Dm at FEmin) for mask comparability. (10−16) In this study, FEmin and MPPS were determined by converting FE to penetration efficiency (PE = 100% – FE) and fit to a logarithmic bi-Gaussian distribution (see eq 2). (44) A bi-Gaussian distribution was chosen as it describes the shape of the data over the measured range and is loosely related to the functional form of FE vs Dm (see eq 1). The interpolated bi-Gaussian fits are shown for all measured samples in Section S3 of the Supporting Information with representative data in Figure 2.
An N95 mask is constructed of a multilayered assemblage of polymer fibers with a distribution of Df to efficiently bind particles of all Dm resulting in FE values that are nearly invariant with Dm with an average FE of (99.9 ± 0.1)% (1σ standard deviation across the 15 measured Dm; see Figures 2 and S50). Except for the sample cut from a N95 mask, the FE of each tested material had a consistent and typical U-shaped curve (increased inertial impaction and interception with larger Dmvs increased diffusion at smaller Dm), (25) see Figure 2, that was exclusive for each material tested (see Section S3 of the Supporting Information for all N and FE vs Dm plots). Some materials, for example, sueded polyester (Polyester 3, poplin weave, 152 yarns inch–2), had a high FE (75%) at Dm < 200 nm and low FE (<25%) at Dm > 500 nm. In comparison, a heavy chiffon (Polyester 4, plain weave, 152 yarns inch–2), exhibited a FE that was only weakly dependent on Dm, but averaged ∼30% across the entire Dm range. A third poplin weave, light chiffon polyester (Polyester 6) of the same yarn count and base-fiber of the previous two fabrics mentioned had an FE < 25% across the range of Dm sizes measured. All three have different areal masses (85 mg inch–2, 107 mg inch–2, and 38 mg inch–2, respectively). These data suggest that FE has a complex interplay between fiber type, sample mass, and construction methods (weave or bond structures). A detailed correlation analysis of these parameters for several of the woven samples is discussed further.
Initial investigations of the efficacy of cloth masks during the 1918 influenza pandemic showed that increasing the number of cloth layers in a facemask (1 layer to 8 layers) was important in the reduction of microbial growth on plates placed downstream of fabrics and exposed to aqueous aerosol droplets containing bacteria. (8,9) Another study showed an analogous benefit by increasing the number of mask layers up to 4 layers of cotton gauze. (9) A similar trend was observed in this study for a lightweight flannel (Cotton 10) using 1 to 5 layers of cloth (see Figure 3). Figure 3A and B show N (particle concentration, particles cm–3) and FE as a function of the number of layers, respectively. The ΔP (see Section S1, Figure S1) across the fabric and FEmin increase monotonically with the number of layers present (see Figure 3C,D). More than 4 layers of this sample exceeded the NIOSH recommended ΔP during exhalation through a fitted mask (245.2 Pa, 25 mm H2O). (46) The quality factor (QF) was also calculated as a function of the number of layers, see Figure 3E. The QF is a commonly used factor to evaluate filter performance under common experimental conditions: (23)
(2)
QF increases as FE increases or ΔP decreases. QFs reported in the literature utilize both ln and log10. (23,36,47) The ln form was used in this study in accordance with the WHO recommendation. (3) The QF was nearly invariant with the number of fabric layers, consistent with multiplicative FEmin and additive changes in ΔP with the number of fabric layers. Lastly, the maximum penetrating particle size (MPPS), defined as the Dm of FEmin, shown in Figure 3F, is 300 nm for a single layer and slightly increases with the number of fabric layers to 350 nm for 4 layers of fabric.

Figure 3

Figure 3. Filtration efficiency (FE) as a function of number of fabric layers for a cotton fiber poplin weave in a lightweight flannel (Cotton 10). (A) Particle number densities per volume of air for the upstream (NU, black) and downstream (ND) particle counters as a function of number of layers (colored lines). Shown NU was measured for a one-layer sample but was representative of the NU measured for all samples. (B) Calculated FE as a function of Dm and number of layers (colored lines). (C) Measured differential pressure (ΔP, Pa) across the material as a function of number of fabric layers. Gray line and plot maximum correspond to NIOSH recommended maximum differential pressure across filter mask for exhaling (245.2 Pa, 25 mm H2O) and inhaling (343.25 Pa, 35 mm H2O), respectively. (27,45) (D) Minimum measured FEmin as a function of number of layers. (E) Quality factor (QF) as a function of number of fabric layers. Horizontal line shows QF = 3 (WHO recommendation). (3) (F) Maximum penetrating particle size (MPPS, nm) as a function of number of fabric layers. Lines in B correspond to bi-Gaussian fits of the data, while lines in C and D are shown to guide the eye.

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The ΔP and FE curves were measured for 38 cloth materials spanning 50 nm ≤ Dm ≤ 825 nm. The FEmin and MPPS were calculated by fitting the distribution to a bi-Gaussian from which QF was determined (see Figure 4 for FEmin and QF and Figure S3 for MPPS; average MPPS across all samples was (252 ± 45) nm). The samples, listed above and in Tables S1 and S2 in Section S2 of the Supporting Information, were classified by fiber content as natural, synthetic, synthetic blend, synthetic/cotton blend, paper, and polypropylene-based. The ΔP and FE of the cloth and paper samples were measured utilizing two layers of the respective materials and as envisioned when constructing a multilayer mask. Synthetic blend 3 (waffle weave, towel) and medical-grade materials (high-density and low-density wraps, HD and LD, respectively) were measured as a single layer due to sample thickness (Synthetic blend 3) or per the manufacturer’s use instructions (wraps). The N95, N95 fabric, and HEPA vacuum bag were constructed of multiple, separable thin layers of synthetic fibers and used as received. As of this writing, the medical-grade wraps are regulated for specific use in healthcare settings and are not currently approved for use in masks in the United States. (48) However, they have been utilized in emergency situations by frontline healthcare workers in the United States and are included only to aid in comparability to cloth and other tested materials. Additionally, while the HEPA vacuum bag tested here contains polypropylene, some HEPA filters may be made from inorganic glasses.

Figure 4

Figure 4. Measured samples categorized by type from left to right: cotton (orange), synthetic (pink), synthetic blend (blue), synthetic/cotton blend (olive), paper (green), and polypropylene-based (light orange). (A) Yarn mass (mg yarn–1), (B) differential pressure across sample (ΔP, Pa), (C) minimum filtration efficiency (FEmin, %), (D) quality factor, QF (kPa–1). The average most penetrating particle size (Dm) across all samples was 252 ± 45 nm with individual values plotted in Figure S5. Uncertainties in B and C are ±4.9 Pa (2× manometer read uncertainty) and ±5% (expanded uncertainty), while uncertainties in D were propagated from B and C. Abbreviations: Polyester (poly) and Cotton (Cott).

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The areal mass yarn–1 (see Figure 4A), a normalized mass value and not an absolute value for each yarn set, spanned almost an order of magnitude across the range of cotton and synthetic samples. The measured ΔP (shown in Figure 4B) also spanned a broad range and was nearly zero for open weaves, for example, Cotton 11 (muslin cotton) and Rayon, and near 334 Pa (34 mm H2O) for the most tightly woven samples (e.g., Cotton 4, down proof ticking), which also was one of the highest yarn count samples measured. The FE of the measured samples ranged from ≈100% for a cut-out section from an N95 mask to 0% (within measurement uncertainty) for Polyester 6 (light chiffon) and Cotton 11 (muslin). Porosity, which was reported for the fabrics measured by Konda et al. (2020), (15) was not calculated for these samples as the length scale of smaller fabric pores (>150 nm) was below the resolution of the imaging instrument (≈ 20 μm, see Figure S4, Figures S54, and S55).
Of the fabrics tested, the top three fabrics with the highest FEmin were 100% cotton: Cotton 4 (down proof ticking), Cotton 8 (woven hand towel), and Cotton 10 (lightweight flannel). The FEmin of Cottons 4 and 8 did not exhibit a statistically significant difference (p > 0.05), assuming 5% uncertainty. Cotton 4 (229 yarns inch–2) exceeded the NIOSH exhalation ΔP limit (245 Pa, 25 mm H2O). (46) Notably, it approached the maximum 343 Pa (35 mm H2O) inhalation ΔP limit recommended for mask use by NIOSH. (27) For comparability of cloth to other tested materials, the measured FEmin of 2 layers of a high performing cloth (Cotton 8, FEmin = 32%) was lower than those measured for the low- (FEmin = 70%) and high-density (FEmin = 86%) medical-grade wraps, the N95 mask (FEmin > 99.9%), and the HEPA vacuum bag (FEmin = 94%). Cotton 8 also had a similar FEmin to the two tested surgical masks (30.5%) and coffee filter (34.4%). The other top cotton fabrics were of average (≈ 150 yarns inch–2) to low (≤100 yarns inch–2) yarn counts, with the lowest being Cotton 8 (≈ 100 yarns inch–2). These materials had 24% ≤ FEmin ≤ 32%, and 57 Pa (5.8 mm H2O) ≤ ΔP ≤ 106 Pa (10.8 mm H2O).
The other two fabrics in the top five were Synthetic blend 2 (twill weave, synthetic, ≈ 200 yarns inch–2) and Polyester 5 (100% polyester, poplin weave, ≈ 230 yarns inch–2). The FEmin performances of these two fabrics do not exhibit a statistically significant difference (see Table S2 in Section S1 in the Supporting Information) assuming an uncertainty of 5%. The synthetic blend had a moderately high yarn count and the second highest ΔP (300 Pa, 30.6 mm H2O) of the all samples. While it met the NIOSH inhalation ΔP limit, (45) it exceeded the exhalation limit. (46) Polyester 5 had a higher yarn count, and the ΔP (104 Pa, 10.6 mm H2O) was well below NIOSH limits. No trends were observed between the type of fabric weave and the measured FEmin. The top five fabrics had weaves ranging from plain (Cotton 4), to block (Cotton 8), to poplin (Cotton 10, Polyester 5) and twill (Synthetic blend 2). Descriptions of weaves can be found in Table S38.
Visual inspection of all top performing, highest FEmin, cotton samples showed some amount of fiber raised from the weave structure. For Cotton 9, which fell within the top half of FEmin performance, and Cotton 10, the raised fibers were nap formed during manufacturing. Nap is an intentional textural feature made from directionally oriented raised fibers that protrude from the 2-dimensional plane of the fabric. Directionality can be lost without intervention (i.e., brushing) as the result of use, and the fibers can form aperiodic patterns similar to those seen in fiber-web fabrics (e.g., Figure 1). Imaging of the two flannels showed they were more heavily napped on their outer side as opposed to their inner side and were the most heavily napped/raised fiber textured of almost all the materials measured (see Figures S15 and S17 in Section S3 of the Supporting Information for imaging of each measured sample and Figure 1B1,2). These two flannel, Cotton 10 and Cotton 9, had similar yarn counts (≈ 150 yarns inch–2) and yarn widths: Cotton 10 (weft) 0.26 mm ± 0.04 mm, (warp) 0.18 mm ± 0.03 mm; Cotton 9 (warp) 0.19 mm ± 0.02 mm, (weft) 0.30 mm ± 0.03 mm). The other top performing cotton fabrics exhibited a similar, raised fiber texture, although not to the same extent. This raised fiber texture was not observed for Polyester 5 or Synthetic blend 2. Additional textural features were observed as raised fibers for Cotton 8 (woven hand towel) and are likely related to fabric construction.
The fabric with the lowest FEmin was Polyester 6 (lightweight chiffon), followed by, in ascending FEmin, Cotton 11 (muslin), Polyester 1 (knit), Rayon, and (Polyester/cotton blend 1, 65% polyester/35% cotton). Four out of the five fabrics with the lowest FEmin were synthetic. Two fabrics, Polyester 6 and Cotton 11, had visually open weave structures compared to all other fabrics analyzed (see Figures S19 and S29 in Section S3 of the Supporting Information). All had yarn counts <250 yarns inch–2. Rayon, Polyester 1, and Polyester 6 had no apparent raised fibers, while Polyester/cotton blend 1 and Cotton 11 had very few observable raised fibers. All were highly breathable, with ΔP < 88.2 Pa (9 mm H2O).
The QF is a relative metric for assessing the overall performance of a filter through the combination of FEmin and ΔP (see eq 2 and Figure 4D). For measurements at similar flow rates, higher QF typically implies improved performance; the WHO recommends utilizing cloth masks with QF > 3. (3)QF ranged from >50 kPa–1 for the N95 mask and HEPA filter to <0.3 kPa–1 for Nylon, Cotton 11 (muslin), and Polyester 6 (lightweight chiffon). Paradoxically, two of the highest QFs were for materials with low FEmin and ΔP: Rayon, QF = (10.8 ± 2.5) kPa–1, FEmin = 2.1%, and ΔP = 1.9 Pa, and Synthetic blend 1, cotton/Spandex, (13.5 ± 2.5) kPa–1, 15.3%, 13 Pa. These QF values are similar to those of the medical grade wraps (QF ≈ 13), surgical masks (average QF ≈ 9), and the N95 fabric (QF ≈ 8), which all had significantly higher FEmin. For these low ΔP materials, FEmin can be improved by constructing masks with many layers (compared to the 2 layers used presently) while maintaining QF (e.g., Figure 2E); however, the number of layers required to obtain the desired FEmin will likely limit functionality in other ways (e.g., FEmin> 30% would require ∼34 layers of Rayon), whereas Cotton 8, woven hand towel, (6.2 kPa ± 0.3) kPa–1, 32%, 62 Pa, had a moderate QF, FEmin, and ΔP, respectively.
The FEmin and ΔP data were statistically evaluated using correlation calculations to determine if relationships existed between measured values and textile parameters for both 100% cotton and 100% polyester fabrics. No statistically significant relationships were found for parameter sets with a sufficient number of samples (n = 5 for 100% polyester and n = 11 for 100% cotton). Details of analyses and results can be found in Tables S34–S37 in Section S5 of the Supporting Information. Sample sizes, after they were controlled for outliers and samples with easily discernible weave patterns and yarn counts, were relatively small (2 < n > 9) and may have attributed to the nonsignificant results. A larger data set from additional samples collected from similarly controlled populations may provide more insight into the effect of these variables on FEmin and ΔP.
In their recent paper, Zhao et al. (2020) (36) related the measured electrostatic properties of common household fabrics (many similar to those studied here) to the fiber chemistry. A similar discussion can be had relating the mechanical filtering ability of a textile to the fiber sources, yarn widths, and textile construction. Mechanical filtration of aerosols by fiber filters is partially dependent on the fiber diameter (49) and the range of diameters of the fibers. (50) Fiber shape may also be an important factor. (51) For synthetic-based apparel textiles, the fibers used to construct yarns tend to be set and have a relatively small variability in width and shape. (39) Generally, natural fibers have more variability, which can be influenced by many factors. For plant-sourced materials (e.g., cotton), these factors can include plant type, growing conditions, and postharvesting processing methods. (52) Cotton has been reported to have fiber diameters from ≈1 μm to ≈22 μm with a similar range of fiber width variability (≈ 20 μm) found within singular crops. For animal-sourced materials (e.g., wool), factors may be animal type/breed (53) and seasonal nutrition levels of the animals. (54) Sheep wools have been reported to have fiber diameters spanning <17 μm to ∼40 μm, (55) with intrabreed variability of ≈20 μm. Although this in range fiber diameter is not as broad as those reported for high filtering synthetic nanofibers (spanning nm to μm), (56) they do provide a broad fiber diameter range and can be used to form fiber-webs for particle filtration. These two features are those often found in filter media that have been shown to have good FE values. (57)
In this study, many woven fabrics were found to form fiber-webs, with the highest concentration being apparent for the 100% cotton flannel samples. These webs, the result of fibers being raised away from the woven structure of the textile, can result in an increase of material disorder, thereby disrupting flowing gas streamlines and providing more surfaces with which the aerosols can interact. This may provide a mechanism to explain why the medium range yarn count (≈ 150 yarns inch–2) Cotton 10 out-performed other fabrics with higher yarn counts (e.g., Cotton 6 and Cotton 13) or synthetics with visually tighter weaves (e.g., Polyester 5). Additionally, this suggests that cover factor, discussed above, may not be a good individual indicator of FE for fabrics displaying these textures. Interestingly, the cotton batting sample (Cotton 14) showed a relatively low FEmin despite consisting of fiber-webs. More research is needed to understand these observations.
In addition to measuring materials from a single type of cloth, two-layered (multimaterial) structures were also investigated in accordance with recent findings by Konda et al. (2020) (15) who measured FEmin > 95% for masks comprised of combinations of two layers of a synthetic and natural fabric using NaCl aerosol that was not size selected. Combinations of cotton and synthetic fabrics identical, or nearly identical, to those outlined in Konda et al. were tested here, and the present results were not consistent with the prior findings (Figure 5A). Because of the low-pressure differentials measured, QF values in Konda et al. were over 1000 kPa–1, 250–500-times higher than measured in this study; see values in Figure 5A. (15) Additional combinations that were exclusive to this investigation (see Figure 5B) were also tested. Konda et al. hypothesized that the measured FEmin resulted from dissimilar layered fabrics increasing electrostatic charge (and hence EB) at the interface between the two layers. In this study, an attempt was also made to increase the charge between the layered structures by rubbing the materials against one another wearing latex gloves for 30 s, as described recently by Zhao et al. (2020) (36) and by Perumalraj (2015) (58) for woven fabrics. This did not significantly impact the measured FEmin (see Figure 5A). Subsequently, the multilayered samples also did not exhibit a significant difference in the measured FEmin when compared to the product of the individual FEmin for the components (sum of individual efficiencies in eq 1), see Figure 5A. Zhao et al. (2020) (36) showed that intense rubbing of materials using latex for 30 s increased the FE for some synthetics but did not increase FE for cotton samples. The high FE reported by Konda et al. (2020) (15) is an intriguing observation that is inconsistent with the results presented here and may be an artifact of sampling a freshly generated NaCl aerosol (e.g., Forsyth et al. (1998)) (59) that has not reached charge equilibrium (either through the passage of time or utilizing a charge neutralizer prior to exposing the aerosol to the sample). Thus, while their FEmin may be applicable to freshly emitted virus-laden particles (e.g., from a cough etc.), they are likely less representative of neutral or weakly charged particles or those that persist in the ambient environment.

Figure 5

Figure 5. Comparison of ΔP, FEmin, and QF for single component layers and mixed layered materials. Samples and mixed samples are coordinated by color. (A) Top 3 samples are single layers and bottom 4 are mixtures using fabric samples either similar, or identical to those reported in Konda et al. (2020). (15) Samples marked with ∗ were rubbed together for 30 s while wearing latex gloves to aid in sample charging as in Zhao et al. (2020). (36) Pink diamonds show data from Konda et al. (2020). (15) (B) Top 3 samples are single layers and bottom 2 are mixtures using fabric samples exclusive to this investigation.

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The presented measured data may be utilized to highlight cloth materials that have a reasonable (based on NIOSH guidelines) ΔP and a high FEmin. These data are discussed further for the best performing cloth samples; microscopic images of each are shown in Figure 6, and data are tabulated in Table 1. The top performing samples show a broad array of structure. This information plus that presented earlier reinforces the fact that visual appearance is not necessarily indicative of a fabric’s filtration and pressure differential properties as previously suggested. (15) For example, the top performing cloth was Cotton 8, which had a visually loose weave, a high FEmin (32.0% ± 1.6%) and low ΔP (61.8 Pa ± 4.9 Pa), and a resulting QF of (6.25 ± 0.27) kPa–1. In comparison, Cotton 6, which had a visually tighter weave and high yarn count (812 yarns inch–2), had a lower FEmin (20.3 ± 1.02) % and a higher ΔP (128.5 ± 4.9) Pa, with a resulting low QF of (1.77 ± 0.04) kPa–1. Another high yarn count fabric (Cotton 13, ≈ 600 yarns inch–2, and the same weave type as Cotton 8) did not make this top five list and had statistically the same FEmin (Cotton 13 FEmin = 19.7% ± 1.0%) as Cotton 8 despite having ∼200 less yarns inch–2.

Figure 6

Figure 6. Transmitted light images of top performing fabrics based on FEmin and ΔP that fall within NIOSH guidelines and are listed in Table 1: (A) Cotton 8 (hand towel, 100% cotton, block weave), (B1, B2) outer and inner surfaces of Cotton 10 (light flannel, poplin weave, 100% cotton), respectively, (C) Polyester 5 (apparel fabric, poplin weave, 100% polyester), (D) Cotton 6 (inner surface, pillowcase, 100% cotton, satin weave, see SI for image of other side), and (E) Polyester 2 (soft spun, 100% polyester, plain weave). Note: Transmitted light grayscale intensities have been inverted so fibers appear lighter relative to voids; all scale bars represent 1 mm with subsections of 200 μm in length.

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Table 1. Top Fabrics Based on FEmin that Fall within NIOSH ΔP Guidelinesa
sample and weavesource/descriptorTPI (yarn inch–2)FEmin (%)ΔP (Pa)QFc (kPa–1)
Cotton 8, blockhand towel102b32.0 ± 1.661.8 ± 4.96.25 ± 0.27
Cotton 10, poplinlightweight flannel15224.3 ± 1.07106.0 ± 4.92.62 ± 0.07
Polyester 5, poplinpoplin apparel fabric22921.4 ± 1.08104.0 ± 4.92.32 ± 0.06
Cotton 6, satinpillowcase81220.3 ± 1.02128.5 ± 4.91.77 ± 0.04
Polyester 2, plainsoft spun apparel fabric15220.2 ± 1.02177.6 ± 4.91.27 ± 0.03
a

Samples and sources, yarns inch–2 (reported as threads inch–2 (TPI) in the table), FEmin, ΔP, and QF for 2 layers of select samples. Uncertainties are 1σ.

b

Sample is constructed of a complex design that results in a variable TPI across the fabric area. Reported value is an estimated average TPI.

c

The WHO recommends utilizing cloth masks with QF > 3. (3)

Other 2-layered cloth materials that offer a similar combination of FEmin and ΔP are shown in Table 1. Using the reasonable assumption that the monotonic change in ΔP with the number of layers (e.g., Cotton 10, lightweight cotton flannel shown in Figure 3C) is similar for other cotton materials, it can be hypothesized that the following material combinations and structures may provide the best breathability and FEmin: a 6-layered mask (by extrapolation from the change in ΔP observed in Figure 3C) of Cotton 8 or a 4-layered assembly of lightweight flannel (sample Cotton 10, FEmin = 48% and ΔP = 216 Pa). Note that these hypothesized constructions are based upon measured FEmin and ΔP data and do not consider the other potential guidelines that may affect mask performance such as the current WHO recommendation of utilization of mixtures of hydrophobic and hydrophilic layers (3) and the effects of mask fitment. (13)
Nonwoven, synthetic fabrics utilized in masks, such as the N95, are often constructed using a melt-bond process. Part of the goal of this process is to stabilize and compress (e.g., calendaring) the manufactured fiber-webs to enhance filtration. Similar steps to engineer the processing of natural fabrics may be necessary to improve, and help maintain, the performance of the above suggested natural fiber materials. Cloth materials with similar microscale structure could be pursued in future investigations. Comparisons between studies measuring cloth FE are challenging due to experimental parameters that may influence mask performance (e.g., sample flow rate, aerosol generation scheme, charge neutralization, and variability in protocols). Future work in this area should use established techniques and officially recognized methods such as EN 1822 or ISO standard methods. On the basis of the findings presented here, other important future research areas of cloth masks may include (1) investigating the relationship between fiber diameters, diameter ranges, and sources with FE and ΔP of select best performing fabrics, (2) an examination of the extent of napping or raised fibers on FE and ΔP and (3) the effect of washing/decontamination on FE, (4) the impact of seams, (5) the influence of relative humidity, or (6) high face velocities such as encountered during coughing or sneezing on FE.

Conclusion

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Cloth materials considered in the construction of facemasks to reduce the transmission of SARS-CoV-2 were evaluated for key factors in mask performance: the filtration efficiency (FE), differential pressure (ΔP), and fabric construction parameters. The results indicate that there is a complex interplay between fabric type, weave, and yarn count and the filtration of nanometer-sized aerosol particles. The best performing cloth materials had moderate yarn counts with visible raised fibers. No measured cloth masks performed as well as an N95. The measured data of mixed cloth assemblies were in contrast to recent measurements by Konda et al., where mixed assemblies of multiple materials did not synergistically impact the measured FEmin beyond the product of individual FE values. (15) The measured data indicate that particle charge does not impact FE for both natural and synthetic fabrics.
Importantly, the presented data were measured under idealized conditions that eliminate or minimize leaks, which are important determinants in mask performance. (13) Other factors that may influence mask performance include fiber width, relative humidity, fabric moisture content, seams across the fabric, fabric nap/texture, and washing or degradation of the fabric. (60) Extending the measured particle size to mimic larger droplets will also aid in understanding fabric filtration.
The method of measuring FE using a combination of aerosol size selection and particle counting is widely available and may enable other research laboratories to perform similar measurements under controlled conditions enabling quantitative comparability of materials. The combination of microscopy and FE applied to other mask materials may allow rapid screening of a broad array of relevant materials or combinations to construct a detailed database for the optimization of FE to reduce exposure to virus-sized particles.

Materials and Methods

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Samples

Samples were acquired from multiple sources by the authors and those acknowledged. Samples were cut into a circular shape of 2.5 cm diameter using a cleaned stainless-steel form and scissors. Samples were used as received and were equilibrated at ∼22 °C and at ambient relative humidity, 30% to 50%, prior to measurement. Most samples were measured in two layers, see text, and were loaded into the sample assembly as individual layers to avoid the potential of perfect registration between the two layers, which may reduce the measured FE.
The measured samples did not shed particles under the flow conditions described in this study. However, materials that meet the HEPA filtration standard may be constructed from multiple types of materials including layered polymers or glass (SiO2) fibers. Using mask materials that meet the HEPA filter standard under conditions they were not designed for, such as cutting or the physical deformation of the filter membrane, may cause the shedding of nano- or microscale fibers from the filter increasing the likelihood of inhalation or ingestion by the mask wearer.
The fabric characterization experiments presented can be split into two sets: (1) material microscopy image analysis for fabric structure to assess material yarn count, weave, and mass measurements, and (2) the filtration efficiency of aerosolized material.

Material Imaging

Imaging was completed with an USB digital microscope (Innovation Beyond Imagination) equipped with 8 brightfield LED lights, a color CMOS sensor, and a high speed 24-bit DSP. Images were collected in diffuse reflected light (LED, ring illuminated) and transmitted light (LED lightbox, Tiktec Laboratories, using size A4 or A5). All images were calibrated to a millimeter length scale, and resolution was calculated to be ∼20 μm (see Supporting Information S4 for details). Calibration was completed for each fabric type imaged. This was necessary as the differing thicknesses of the fabrics resulted in utilization of slightly different fields of view for each sample set. Preliminary processing, yarn counts, and yarn width measurements were completed in ImageJ (v. 1.8.0_112 with Fiji). (61,62) All images were length-scale calibrated and converted to an eight-bit gray scale before analyses. Additional image processing was completed in Digital Surf (Mountain Laboratories, v. 8) and was utilized to create the inverted grayscale images shown in Figure 1. Reflected and transmitted light images, yarn widths, and yarn count data can be found in SI S3.

Weave Types and Yarn Count, Width, and Mass Measurements

Reported weave types were either determined by visual inspection following the descriptions outlined in Table S38 in Section S7 of the Supporting Information or listed as described by the manufacturer. Two or more different sample sites were analyzed for each fabric for determination of yarn widths, and, unless otherwise stated, n = 20 yarns were measured. Measurements were completed manually and recorded using the measure subroutine in ImageJ. Widths were measured between yarn crossing junctions (i.e., not at the overlap of the yarns). Yarn counts were completed by measuring 1 mm across either axis of an image (starting in a void space) and then counting the number of yarns that fell under that line. Both front interior and exterior faced yarns were counted. Mean, standard deviation (reported to 1σ), minimum, and maximum values are reported for the warp and weft yarn widths (see Section S3 of the Supporting Information). Warp and weft yarn directions were utilized in this study following textile industry practices. Warp yarns are those placed on a loom before being interwoven with weft yarns (see Figure S4). Identification of these yarns was completed by either visual inspection of the selvedge or by analyzing the weave and looking for reed marks (marks left by a tool used to separate and space yams) in the samples.
Yarn counts were also conducted separately in the warp and weft directions. Reported yarn counts are the average results of n = 5 measurements across 2 or more different sample sites. In cases where there was no clear warp:weft yarn structure (e.g., knits, block, and waffle weave samples), a single value is reported for the number of yarns counted in along 1 mm of the horizontal direction of the image. Mass yarn–1 measurements are relative to a 1 cm2 area and were calculated by dividing measured masses by the total number of yarns (sum of warp and weft yarns) counted for the same size area.

Filtration Efficiency

FE measurements mimicked Parts 3 and 5 of the EN 1822 mask filtration protocol (aerosol remains un-neutralized after size selection) or the ISO 29463 testing standard (aerosol is reneutralized after size selection); see Figure S1. Aerosol was generated from a 10 mg mL–1 aqueous solution of NaCl using a constant output atomizer supplied with dry (dew point < −75 °C), HEPA-filtered air (25 psig). Of the 2.2 L min–1 flow that was generated, 0.3 L min–1 was sampled and conditioned using two silica gel diffusion dryers (desiccant was replaced daily prior to data collection). The aerosol was then passed through a soft X-ray charge neutralizer and size selected, at a mobility diameter (Dm), using a differential mobility analyzer (DMA) and a 10:1 sheath:aerosol flow. Under these experimental conditions, the range of aerosols selected was 50 nm ≤ Dm ≤ 825 nm. The ∼0.3 L min–1 of aerosol exiting the DMA was then mixed with ∼2.7 L min–1 HEPA-filtered dilution air (ambient laboratory air with ∼30% relative humidity) and either passed to a condensation particle counter (CPC) or through a 25 mm plastic filter holder (with stainless steel filter backing) to a CPC to measure the upstream (NU) and downstream (ND) particle number densities, respectively. Both CPCs sampled at 1.5 L min–1 and the face velocity at the filter holder was ≈ 6.3 cm s–1 and in line with NIOSH guidelines. Conductive (carbon black impregnated) silicone tubing was used throughout the experiment to prevent aerosol scavenging. The material under test was held in a plastic filter holder with a polymer gasket that electrically isolated the material. No attempts were made to electrically ground the tested material.
The downstream CPC had been previously calibrated by a spectroscopic method using ammonium sulfate aerosol, see Radney and Zangmeister (2018). (40) Using this method, the CPC calibration is better than 3% for number densities (N) < 2 × 104 cm–3; see additional details in the Supporting Information. At larger values of N, NU and ND deviated from each other, so they were compared multiple times daily using the described arrangement without fabric in the filter assembly. Both CPCs (TSI 3775) also switched between a single particle counting mode and a photometric counting mode at ∼5 × 104 cm–3. The transition between modes was set by the manufacturer and automated based on the rate of change of N as a function of time. The transition regime of two instruments behaved similarly, but their set points may have been slightly offset under some measurement conditions. Two methods were used to account for this variation: (1) measurements with 4.5 × 104 cm–3 ≤ ND ≤ 5.5 × 104 cm–3 were excluded from the determination of the minimum FE, and (2) separate comparison curves between NU and ND were used for ND ≥ 4.5 × 104 cm–3 and ND ≤ 5.5 × 104 cm–3 (see Figure S2).
Experimental and data acquisition were controlled by custom software written in our laboratory. Dm (15 samples equally log spaced spanning 50 nm ≤ Dm ≤ 825 nm) was set by a computer and the particle counts were allowed to stabilize for 30 s. The NU and ND were then recorded for 30 s at 1 Hz, after which the next Dm was sequentially selected. The 30 s data (representing one technical replicate) were then averaged and a 1σ standard deviation calculated. The FE was then calculated from eq 1 with the relative uncertainty in FE including the propagated 1σ uncertainties in NU and ND. The total time required to collect an FE curve for a single fabric sample was ∼15 min.
For all presented FE values, we assume an uncertainty of 5% that derives from (1) measured 1σ standard deviations of N ≈ 2.5%, (2) CPC accuracy ≈ 3% (we assume this is constant for all N and not just N < 2 × 104 cm–3), (3) an ∼2% day-to-day variability in FE for the same sample, and (D) ∼1% sample-to-sample variability in FE for the same material.
The calculated FE curves were then converted to penetration efficiency (PE = 100% – FE) and fit as a function of Dm to a logarithmic bi-Gaussian distribution (i.e., a logarithmically transformed bi-Gaussian distribution):
(3)
where PEmax is the maximum penetration efficiency of the material. To be consistent with other reports, we report all data as the filtration efficiency (FE) as shown in eq 1.
The differential pressure (ΔP, Pa) across the filter sample was measured using one of two manometers with ranges of 0 to 245.17 Pa and 0 to 490.3 Pa; to convert from Pa to mm H2O to Pa, divide by 9.80665 Pa. (63) The reported ΔP across the filter represents the difference between the filter assembly with and without a filter present. Uncertainty in ΔP was calculated as twice the manometer read error (±4.9 Pa, 1σ).

Outlier and Correlation Calculations

The 100% cotton (n = 11) and 100% polyester (n = 5) sample sets were selected for correlation calculations by controlling for fiber type (cotton or polyester) and utilizing data sets on fabrics only with definite yarn counts. The data sets consisted of the following parameters: FEmin (%), ΔP (mm H2O), weft and warp yarn widths (mm), weft and warp yarn counts (yarn inch–1), yarn count (yarns inch–2), and areal yarn mass (mg yarn–1). Parameter outliers were determined by calculating the first (25%) and third (75%) quartiles, determining the interquartile range from these values, calculating the upper and lower bounds of the range, and then rejecting any data value that fell outside of these bounds. Results from these calculations along with other descriptive statistical values for each parameter analyzed are presented in Tables S34 and S35 in Section S5 of the Supporting Information.
The remaining data were tested for normal distribution using the Shapiro-Wilk Test for Normality. (64) Normality test results were employed to determine whether to use a parametric (Pearson Product Moment Correlation, normally distributed data sets, eq 4) or a nonparametric (Spearman Rank-Order Correlation, non-normally distributed data sets, eq 5) correlation equation on pairs of data sets:
(4)
(5)
where xi and yi are raw values for the ith set, n is the number of observations, and rg(xi) and rg(yi) are converted ranks for defined values.
These tests were selected under the assumptions that (1) variables are independent, (2) the values in the nonparametric sets are interval variables, and (3) there is a monotopic relationship between variables. Paired sets where both data sets failed the Shapiro-Wilk test and paired sets where only one failed the Shapiro-Wilk test were treated with the Spearman test, and the Pearson test was only utilized with pairs that both tested positive for normality. Pearson coefficients (rp), and Spearman coefficients (rs), and their corresponding p-values (ρp and ρs, respectively) were calculated in SigmaPlot (version 14). (65) Results are reported in Tables S36 and S37 in Section S5 of the Supporting Information. Calculated coefficients were evaluated for significance based on the following criteria: variables with p-values below 0.050 and positive (+) coefficients tend to increase together; pairs with p-values below 0.050 and negative coefficients (−) have one variable that tends to decrease while the other increases. There is no significant relationship between two variables for pairs where the p-values are greater than 0.050. (65) Presented correlation results should be interpreted cautiously given the small number of observations in this study per the controlled population sizes.

Supporting Information

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The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsnano.0c05025.

  • FE measurement description and schematic, measurements of particle counts for NU and ND and FE as function of Dm, description of method of image analysis, microscopic images, yarn widths, number of yarns in weft and warp directions, number of yarns cm–2 for each measured sample (PDF)

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Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.

Author Information

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  • Corresponding Author
  • Authors
    • James G. Radney - Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States;  Orcidhttp://orcid.org/0000-0001-7324-8769
    • Edward P. Vicenzi - Museum Conservation Institute, Smithsonian Institution, Suitland, Maryland 20746, United States;  Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
    • Jamie L. Weaver - Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States;  Museum Conservation Institute, Smithsonian Institution, Suitland, Maryland 20746, United States;  Orcidhttp://orcid.org/0000-0002-6762-0568
  • Funding

    C.Z., J.R., and J.W. were funded by the National Institute of Standards and Technology. E.V. was funded by the Smithsonian Institution.

  • Notes
    Trade names and commercial products are identified in this paper to specify the experimental procedures in adequate detail. This identification does not imply recommendation or endorsement by the authors or by the National Institute of Standards and Technology, nor does it imply that the products identified are necessarily the best available for the purpose.
    The authors declare no competing financial interest.

Acknowledgments

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The authors wish to acknowledge Gail Porter for the donation of samples for this work and Pamela Chu, David LaVan, and Rob Dimeo at NIST for technical discussions and organization and the design and implementation of the TOC artwork, respectively. The authors would also like to thank Darcy Gray and Nik Dukich of Tom Bihn, Inc. for supplying of some samples and technical discussions of suitable fabric materials.

References

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This article references 65 other publications.

  1. 1
    Health Emergencies Preparedness and Response Team. Advice on the Use of Masks in the Context of COVID-19: Interim Guidance, 6 April 2020, 2020. Advice on the Use of Masks in the Context of COVID-19: Interim Guidance; WHO, 2020. https://apps.who.int/iris/handle/10665/331693 (accessed 06-23-2020).
    Google Scholar
    There is no corresponding record for this reference.
  2. 2
    United States Centers for Disease Control and Prevention. Coronavirus Disease 2019 (COVID-2019); CDC, 2020. https://www.cdc.gov/coronavirus/ (accessed 06-23-2020).
    Google Scholar
    There is no corresponding record for this reference.
  3. 3
    Health Emergencies Preparedness and Response Team. Advice on the Use of Masks in the Context of COVID-19: Interim Guidance, 5 June 2020; WHO, 2020. https://www.who.int/publications/i/item/advice-on-the-use-of-masks-the-community-during-home-care-and-in-health-care-settings-in-the-context-of-the-novel-coronavirus-(2019-ncov)-outbreak (accessed 06-23-2020).
    Google Scholar
    There is no corresponding record for this reference.
  4. 4
    Neuman, B.; Adair, B.; Yoshioka, C.; Quispe, J.; Orca, G.; Kuhn, P.; Milligan, R.; Yeager, M.; Buchmeier, M. Supramolecular Architecture of Severe Acute Respiratory Syndrome Coronavirus Revealed by Electron Cryomicroscopy. J. Virol. 2006, 80, 7918– 7928,  DOI: 10.1128/JVI.00645-06
    [Crossref], [PubMed], [CAS], Google Scholar
    4
    Supramolecular architecture of severe acute respiratory syndrome coronavirus revealed by electron cryomicroscopy
    Neuman, Benjamin W.; Adair, Brian D.; Yoshioka, Craig; Quispe, Joel D.; Orca, Gretchen; Kuhn, Peter; Milligan, Ronald A.; Yeager, Mark; Buchmeier, Michael J.
    Journal of Virology (2006), 80 (16), 7918-7928CODEN: JOVIAM; ISSN:0022-538X. (American Society for Microbiology)
    Coronavirus particles are enveloped and pleomorphic and are thus refractory to crystn. and symmetry-assisted reconstruction. A novel methodol. of single-particle image anal. was applied to selected virus features to obtain a detailed model of the oligomeric state and spatial relationships among viral structural proteins. Two-dimensional images of the S, M, and N structural proteins of severe acute respiratory syndrome coronavirus and two other coronaviruses were refined to a resoln. of ∼4 nm. Proteins near the viral membrane were arranged in overlapping lattices surrounding a disordered core. Trimeric glycoprotein spikes were in register with four underlying ribonucleoprotein densities. However, the spikes were dispensable for ribonucleoprotein lattice formation. The ribonucleoprotein particles displayed coiled shapes when released from the viral membrane. Our results contribute to the understanding of the assembly pathway used by coronaviruses and other pleomorphic viruses and provide the first detailed view of coronavirus ultrastructure.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28Xot1yrtr0%253D&md5=aa64ccff2765ad96e37fdcfa9aa90fd5
  5. 5
    Liu, Y.; Ning, Z.; Chen, Y.; Guo, M.; Liu, Y.; Gali, N. K.; Sun, L.; Duan, Y.; Cai, J.; Westerdahl, D.; Liu, X.; Xu, K.; Ho, K.; Kan, H.; Fu, Q.; Lan, K. Aerodynamic Analysis of SARS-COV-2 in Two Wuhan Hospitals. Nature 2020, 582, 557– 560,  DOI: 10.1038/s41586-020-2271-3
    [Crossref], [PubMed], [CAS], Google Scholar
    5
    Aerodynamic analysis of SARS-CoV-2 in two Wuhan hospitals
    Liu, Yuan; Ning, Zhi; Chen, Yu; Guo, Ming; Liu, Yingle; Gali, Nirmal Kumar; Sun, Li; Duan, Yusen; Cai, Jing; Westerdahl, Dane; Liu, Xinjin; Xu, Ke; Ho, Kin-fai; Kan, Haidong; Fu, Qingyan; Lan, Ke
    Nature (London, United Kingdom) (2020), 582 (7813), 557-560CODEN: NATUAS; ISSN:0028-0836. (Nature Research)
    The ongoing outbreak of coronavirus disease 2019 (COVID-19) has spread rapidly on a global scale. Although it is clear that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is transmitted through human respiratory droplets and direct contact, the potential for aerosol transmission is poorly understood. We investigated the aerodynamic nature of SARS-CoV-2 by measuring viral RNA in aerosols in different areas of 2 Wuhan hospitals during the outbreak of COVID-19 in Feb. and March 2020. The concn. of SARS-CoV-2 RNA in aerosols that was detected in isolation wards and ventilated patient rooms was very low, but it was higher in the toilet areas used by the patients. Levels of airborne SARS-CoV-2 RNA in the most public areas was undetectable, except in 2 areas that were prone to crowding; this increase was possibly due to individuals infected with SARS-CoV-2 in the crowd. Some medical staff areas initially had high concns. of viral RNA with aerosol size distributions that showed peaks in the submicrometer and(or) supermicrometer regions; however, these levels were reduced to undetectable levels after implementation of rigorous sanitization procedures. Although we have not established the infectivity of the virus detected in these hospital areas, we propose that SARS-CoV-2 may have the potential to be transmitted through aerosols. Our results indicate that room ventilation, open space, sanitization of protective apparel, and proper use and disinfection of toilet areas can effectively limit the concn. of SARS-CoV-2 RNA in aerosols. Future work should explore the infectivity of aerosolized virus.
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  6. 6
    Prather, K.; Wang, C.; Schooley, R. Reducing Transmission of SARS-COV-2. Science 2020, 368, 1422– 1424,  DOI: 10.1126/science.abc6197
    [Crossref], [PubMed], [CAS], Google Scholar
    6
    Reducing transmission of SARS-CoV-2
    Prather, Kimberly A.; Wang, Chia C.; Schooley, Robert T.
    Science (Washington, DC, United States) (2020), 368 (6498), 1422-1424CODEN: SCIEAS; ISSN:1095-9203. (American Association for the Advancement of Science)
    A review. Respiratory infections occur through the transmission of virus-contg. droplets (>5 to 10μm) and aerosols (≤5μm) exhaled from infected individuals during breathing, speaking, coughing, and sneezing. Traditional respiratory disease control measures are designed to reduce transmission by droplets produced in the sneezes and coughs of infected individuals. However, a large proportion of the spread of coronavirus disease 2019 (COVID-19) appears to be occurring through airborne transmission of aerosols produced by asymptomatic individuals during breathing and speaking . Aerosols can accumulate, remain infectious in indoor air for hours, and be easily inhaled deep into the lungs. For society to resume, measures designed to reduce aerosol transmission must be implemented, including universal masking and regular, widespread testing to identify and isolate infected asymptomatic individuals.
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  7. 7
    Milton, D.; Fabian, M.; Angel, M.; Perez, D.; Mcdevitt, J. Influenza Virus Aerosols in Human Exhaled Breath: Particle Size, Culturability, and Effect of Surgical Masks. PLoS Pathog. 2010, 9, e1003205  DOI: 10.1371/journal.ppat.1003205
    [Crossref], Google Scholar
    There is no corresponding record for this reference.
  8. 8
    Weaver, G. Droplet Infection and Its Prevention by the Face Mask. J. Infect. Dis. 1919, 24, 218– 230,  DOI: 10.1093/infdis/24.3.218
    [Crossref], Google Scholar
    There is no corresponding record for this reference.
  9. 9
    Kellogg, W.; Macmillan, G. An Experimental Study of the Efficacy of Gauze Face Masks. Am. J. Public Health 1920, 10, 34– 42,  DOI: 10.2105/AJPH.10.1.34
    [Crossref], [CAS], Google Scholar
    9
    AN EXPERIMENTAL STUDY OF THE EFFICACY OF GAUZE FACE MASKS
    Kellogg W H; Macmillan G
    American journal of public health (New York, N.Y. : 1912) (1920), 10 (1), 34-42 ISSN:0271-4353.
    Masks have not been proved efficient enough to warrant compulsory application for the checking of epidemics, according to Dr. Kellogg, who has conducted a painstaking investigation with gauzes. This investigation is scientific in character, omitting no one of the necessary factors. It ought to settle the much argued question of masks for the public.
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  10. 10
    Rengasamy, S.; Eimer, B.; Shaffer, R. Simple Respiratory Protection-Evaluation of the Filtration Performance of Cloth Masks and Common Fabric Materials against 20–1000 nm Size Particles. Ann. Occup. Hyg. 2010, 54, 789– 798,  DOI: 10.1093/annhyg/meq044
    [Crossref], [PubMed], [CAS], Google Scholar
    10
    Simple Respiratory Protection-Evaluation of the Filtration Performance of Cloth Masks and Common Fabric Materials Against 20-1000 nm Size Particles
    Rengasamy, Samy; Eimer, Benjamin; Shaffer, Ronald E.
    Annals of Occupational Hygiene (2010), 54 (7), 789-798CODEN: AOHYA3; ISSN:0003-4878. (Oxford University Press)
    A shortage of disposable filtering facepiece respirators can be expected during a pandemic respiratory infection such as influenza A. Some individuals may want to use common fabric materials for respiratory protection because of shortage or affordability reasons. To address the filtration performance of common fabric materials against nano-size particles including viruses, five major categories of fabric materials including sweatshirts, T-shirts, towels, scarves, and cloth masks were tested for polydisperse and monodisperse aerosols (20-1000 nm) at two different face velocities (5.5 and 16.5 cm s-1) and compared with the penetration levels for N95 respirator filter media. The results showed that cloth masks and other fabric materials tested in the study had 40-90% instantaneous penetration levels against polydisperse NaCl aerosols employed in the National Institute for Occupational Safety and Health particulate respirator test protocol at 5.5 cm s-1. Similarly, varying levels of penetrations (9-98%) were obtained for different size monodisperse NaCl aerosol particles in the 20-1000 nm range. The penetration levels of these fabric materials against both polydisperse and monodisperse aerosols were much higher than the penetrations for the control N95 respirator filter media. At 16.5 cm s-1 face velocity, monodisperse aerosol penetrations slightly increased, while polydisperse aerosol penetrations showed no significant effect except one fabric mask with an increase. Results obtained in the study show that common fabric materials may provide marginal protection against nanoparticles including those in the size ranges of virus-contg. particles in exhaled breath.
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  11. 11
    Shakya, K.; Noyes, A.; Kallin, R.; Peltier, R. Evaluating the Efficacy of Cloth Facemasks in Reducing Particulate Matter Exposure. J. Exposure Sci. Environ. Epidemiol. 2017, 27, 352– 357,  DOI: 10.1038/jes.2016.42
    [Crossref], [PubMed], [CAS], Google Scholar
    11
    Evaluating the efficacy of cloth facemasks in reducing particulate matter exposure
    Shakya, Kabindra M.; Noyes, Alyssa; Kallin, Randa; Peltier, Richard E.
    Journal of Exposure Science & Environmental Epidemiology (2017), 27 (3), 352-357CODEN: JESEBS; ISSN:1559-0631. (Nature Publishing Group)
    Inexpensive cloth masks are widely used in developing countries to protect from particulate pollution albeit limited data on their efficacy exists. This study examd. the efficiency of four types of masks (three types of cloth masks and one type of surgical mask) commonly worn in the developing world. Five monodispersed aerosol sphere size (30, 100, and 500 nm, and 1 and 2.5 μm) and dild. whole diesel exhaust was used to assess facemask performance. Among the three cloth mask types, a cloth mask with an exhaust valve performed best with filtration efficiency of 80-90% for the measured polystyrene latex (PSL) particle sizes. Two styles of com. available fabric masks were the least effective with a filtration efficiency of 39-65% for PSL particles, and they performed better as the particle size increased. When the cloth masks were tested against lab-generated whole diesel particles, the filtration efficiency for three particle sizes (30, 100, and 500 nm) ranged from 15% to 57%. Std. N95 mask performance was used as a control to compare the results with cloth masks, and our results suggest that cloth masks are only marginally beneficial in protecting individuals from particles <2.5 μm. Compared with cloth masks, disposable surgical masks are more effective in reducing particulate exposure.
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  12. 12
    Davies, A.; Thompson, K.; Giri, K.; Kafatos, G.; Walker, J.; Bennett, A. Testing the Efficacy of Homemade Masks: Would They Protect in an Influenza Pandemic?. Disaster Med. Public Health Prep 2013, 7, 413– 418,  DOI: 10.1017/dmp.2013.43
    [Crossref], [PubMed], [CAS], Google Scholar
    12
    Testing the efficacy of homemade masks: would they protect in an influenza pandemic?
    Davies Anna; Thompson Katy-Anne; Giri Karthika; Kafatos George; Walker Jimmy; Bennett Allan
    Disaster medicine and public health preparedness (2013), 7 (4), 413-8 ISSN:.
    OBJECTIVE: This study examined homemade masks as an alternative to commercial face masks. METHODS: Several household materials were evaluated for the capacity to block bacterial and viral aerosols. Twenty-one healthy volunteers made their own face masks from cotton t-shirts; the masks were then tested for fit. The number of microorganisms isolated from coughs of healthy volunteers wearing their homemade mask, a surgical mask, or no mask was compared using several air-sampling techniques. RESULTS: The median-fit factor of the homemade masks was one-half that of the surgical masks. Both masks significantly reduced the number of microorganisms expelled by volunteers, although the surgical mask was 3 times more effective in blocking transmission than the homemade mask. CONCLUSION: Our findings suggest that a homemade mask should only be considered as a last resort to prevent droplet transmission from infected individuals, but it would be better than no protection.
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  13. 13
    Lai, A.; Poon, C.; Cheung, A. Effectiveness of Facemasks to Reduce Exposure Hazards for Airborne Infections among General Populations. J. R. Soc., Interface 2012, 9, 938– 948,  DOI: 10.1098/rsif.2011.0537
    [Crossref], [PubMed], [CAS], Google Scholar
    13
    Effectiveness of facemasks to reduce exposure hazards for airborne infections among general populations
    Lai A C K; Poon C K M; Cheung A C T
    Journal of the Royal Society, Interface (2012), 9 (70), 938-48 ISSN:.
    Facemasks are widely used as a protective measure by general public to prevent inhalation of airborne pathogens including seasonal, swine and other forms of influenza and severe acute respiratory syndrome (SARS), etc. However, scientific data on effectiveness of facemasks in reducing infections in the community are extremely limited and even inconsistent. In this work, two manikins labelled as 'source' and 'susceptible' were used to measure the protection provided by facemasks under various emission scenarios. The source was modified to generate polydisperse ultrafine particles, whereas the susceptible was modified to mimic a realistic breathing pattern. The facemask was challenged by both pseudo-steady and highly transient emissions generated by an expiratory process where parameters, such as separation distance between manikins, emission velocity and expiratory duration, were controlled and measured systematically. Performances of four different types of facemask fits, varying from ideal to normal wearing practice, were also investigated. Under the pseudo-steady concentration environment, facemask protection was found to be 45 per cent, while under expiratory emissions, protection varied from 33 to 100 per cent. It was also observed that the separation between the source and the manikin was the most influential parameter affecting facemask protection.
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  14. 14
    Van Der Sande, M.; Teunis, P.; Sabel, R. Professional and Home-Made Face Masks Reduce Exposure to Respiratory Infections among the General Population. PLoS One 2008, 3, e2618  DOI: 10.1371/journal.pone.0002618
    [Crossref], [PubMed], Google Scholar
    There is no corresponding record for this reference.
  15. 15
    Konda, A.; Prakash, A.; Moss, G.; Schmoldt, M.; Grant, G.; Guha, S. Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks. ACS Nano 2020, 14, 6339– 6347,  DOI: 10.1021/acsnano.0c03252
    [ACS Full Text ACS Full Text], [CAS], Google Scholar
    15
    Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks
    Konda, Abhiteja; Prakash, Abhinav; Moss, Gregory A.; Schmoldt, Michael; Grant, Gregory D.; Guha, Supratik
    ACS Nano (2020), 14 (5), 6339-6347CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
    The emergence of a pandemic affecting the respiratory system can result in a significant demand for face masks. This includes the use of cloth masks by large sections of the public, as can be seen during the current global spread of COVID-19. However, there is limited knowledge available on the performance of various commonly available fabrics used in cloth masks. Importantly, there is a need to evaluate filtration efficiencies as a function of aerosol particulate sizes in the 10 nm to 10μm range, which is particularly relevant for respiratory virus transmission. We have carried out these studies for several common fabrics including cotton, silk, chiffon, flannel, various synthetics, and their combinations. Although the filtration efficiencies for various fabrics when a single layer was used ranged from 5 to 80% and 5 to 95% for particle sizes of <300 nm and >300 nm, resp., the efficiencies improved when multiple layers were used and when using a specific combination of different fabrics. Filtration efficiencies of the hybrids (such as cotton-silk, cotton-chiffon, cotton-flannel) was >80% (for particles <300 nm) and >90% (for particles >300 nm). We speculate that the enhanced performance of the hybrids is likely due to the combined effect of mech. and electrostatic-based filtration. Cotton, the most widely used material for cloth masks performs better at higher weave densities (i.e., thread count) and can make a significant difference in filtration efficiencies. Our studies also imply that gaps (as caused by an improper fit of the mask) can result in over a 60% decrease in the filtration efficiency, implying the need for future cloth mask design studies to take into account issues of "fit" and leakage, while allowing the exhaled air to vent efficiently. Overall, we find that combinations of various commonly available fabrics used in cloth masks can potentially provide significant protection against the transmission of aerosol particles.
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  16. 16
    Macintyre, C.; Seale, H.; Dung, T.; Hien, N.; Nga, P.; Chughtai, A.; Rahman, B.; Dwyer, D.; Wang, Q. A Cluster Randomised Trial of Cloth Masks Compared with Medical Masks in Healthcare Workers. Bmj Open 2015, 5, e006577  DOI: 10.1136/bmjopen-2014-006577
    [Crossref], [PubMed], Google Scholar
    There is no corresponding record for this reference.
  17. 17
    Kulkarni, P.; Baron, P.; Willeke, K. Aerosol Measurement: Principles, Techniques and Applications. 3rd ed.; John Wiley & Sons, Inc.: Hoboken, NJ, 2011; 107– 128.
    [Crossref], Google Scholar
    There is no corresponding record for this reference.
  18. 18
    Brown, R.; Wake, D. Air Filtration by Interception—Theory and Experiment. J. Aerosol Sci. 1991, 22, 181– 186,  DOI: 10.1016/0021-8502(91)90026-E
    [Crossref], [CAS], Google Scholar
    18
    Air filtration by interception - theory and experiment
    Brown, R. C.; Wake, D.
    Journal of Aerosol Science (1991), 22 (2), 181-6CODEN: JALSB7; ISSN:0021-8502.
    A model of aerosol particle capture in filters, by interception, is developed, by using a more general approach than simple single-fiber theory. A simple relationship exists between aerosol penetration and particle size, fiber size, and the quotient of pressure drop and filtration velocity. Agreement between theory and expt. is good, both for the fundamental dependence of penetration on aerosol size and for the abs. values of penetration.
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  19. 19
    Emi, H.; Okuyama, K.; Yoshioka, N. Prediction of Collection Efficiency of Aerosols by High-Porosity Fibrous Filter. J. Chem. Eng. Jpn. 1973, 6, 349– 354,  DOI: 10.1252/jcej.6.349
    [Crossref], [CAS], Google Scholar
    19
    Prediction of collection efficiency of aerosols by a high-porosity fibrous filter
    Emi, Hitoshi; Okuyama, Kikuo; Yoshioka, Naoya
    Journal of Chemical Engineering of Japan (1973), 6 (4), 349-54CODEN: JCEJAQ; ISSN:0021-9592.
    In the filtration of aerosols by a high-porosity fiber mat, the deposition of particles smaller than a few microns in diam. on a fiber depends on the combined effect of initial impaction, Brownian diffusion, gravitational settling, and direct interception, when neither particles nor filters are elec. charged. The overall collection efficiency vs. particle diam. curves show distinct min. Decreasing parts of the efficiency vs. the particle diam. are in the diffusion-predominant region, whereas increasing parts are gravity-predominant in the low-velocity range, which is shifted to inertia with increasing velocity. The overall collection efficiency vs. linear gas velocity curves also show distinct min. Results can be used for designing fibrous filters with porosities >0.98.
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  20. 20
    Stechkina, I.; Fuchs, N. Studies on Fibrous Aerosol Filters-I. Calculation of Diffusional Deposition of Aerosols in Fibrous Filters. Ann. Occup. Hyg. 1966, 9, 59– 64,  DOI: 10.1093/annhyg/9.2.59
    [Crossref], Google Scholar
    There is no corresponding record for this reference.
  21. 21
    Stechkina, I.; Kirsch, A.; Fuchs, N. Studies on Fibrous Aerosol Filters-IV Calculation of Aerosol Deposition in Model Filters In the Range of Maximum Penetration. Ann. Occup. Hyg. 1969, 12, 1– 8,  DOI: 10.1093/annhyg/12.1.1
    [Crossref], [PubMed], [CAS], Google Scholar
    21
    Studies on fibrous aerosol filters. IV. Calculation of aerosol deposition in model filters in the range of maximum penetration
    Stechkina I B; Kirsch A A; Fuchs N A
    The Annals of occupational hygiene (1969), 12 (1), 1-8 ISSN:0003-4878.
    There is no expanded citation for this reference.
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  22. 22
    Lee, K.; Liu, B. Theoretical Study of Aerosol Filtration by Fibrous Filters. Aerosol Sci. Technol. 1982, 1, 147– 161,  DOI: 10.1080/02786828208958584
    [Crossref], Google Scholar
    There is no corresponding record for this reference.
  23. 23
    Podgórski, A.; Bałazy, A.; Gradoń, L. Application of Nanofibers to Improve the Filtration Efficiency of the Most Penetrating Aerosol Particles in Fibrous Filters. Chem. Eng. Sci. 2006, 61, 6804– 6815,  DOI: 10.1016/j.ces.2006.07.022
    [Crossref], [CAS], Google Scholar
    23
    Application of nanofibers to improve the filtration efficiency of the most penetrating aerosol particles in fibrous filters
    Podgorski, Albert; Balazy, Anna; Gradon, Leon
    Chemical Engineering Science (2006), 61 (20), 6804-6815CODEN: CESCAC; ISSN:0009-2509. (Elsevier Ltd.)
    Conventional, mech. fibrous filters made of microfibers exhibit a local min. of fractional collection efficiency in the aerosol particle size-range between 100 and 500 nm, which is called the most penetrating particle size (MPPS). Simple theor. calcns. predict that this efficiency may be significantly increased using nanofibrous media. The main objective of this paper is an exptl. verification of these expectations and simultaneously checking whether this anticipated gain in the filtration efficiency is not overpaid with an excessive pressure drop. For this purpose we developed a modified melt-blown technol., which allowed us to produce filters composed of micrometer as well as nanometer sized fibers. One conventional microfibrous filter and five nanofibrous filters were examd. The complete structural characteristics, pressure drop and efficiency of removal of aerosol particles with diams. 10-500 nm were detd. for all media. The results of the expts. confirmed that using nanofibrous filters a significant growth of filtration efficiency for the MPPS range can be achieved and the pressure drop rises moderately. Simultaneously, we noticed a shift of the MPPS towards smaller particles. Consequently, the quality factor for bilayer systems composed of a microfibrous support and a nanofibrous facial layer was considerably higher than this one for a conventional microfibrous filter alone. Addnl., it was found that utilization of many-layer nanofibrous filters combined with a single microfibrous backing layer is even more profitable from the quality factor standpoint. Comparing exptl. results with theor. calcns. based on the single-fiber theory we concluded that for microfibrous filters a fairly good agreement can be obtained if the resistance-equiv. fiber diam. is used in calcns. instead of the mean count diam. detd. from the SEM images anal.; in the latter case, filtration efficiency computed theor. is slightly overestimated. This is even more evident for nanofibrous media, suggesting that in such case a structural filter inhomogeneity has a strong influence on the filter efficiency and its resistance and one should strive for minimization of this effect manufg. nanofibrous filters as homogeneous as possible. We can finally conclude that fibrous filters contg. nanofibers, which are produced using the melt-blown technique, are very promising and economic tools to enhance filtration of the most penetrating aerosol particles.
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  24. 24
    Specification for HEPA Filters Used by DOE Contractors; DOE-STD-3020–2015; U. S. Department of Energy: Washington, D.C., 2015; pp 1– 29.
    Google Scholar
    There is no corresponding record for this reference.
  25. 25
    Hinds, W. C. Aerosol Technology: Properties, Behavior, and Measurement of Airborne Particles, 2nd ed.; John Wiley & Sons, Inc.: New York, 1999; pp 182– 205.
    Google Scholar
    There is no corresponding record for this reference.
  26. 26
    Rengasamy, S.; Shaffer, R.; Williams, B.; Smit, S. A Comparison of Facemask and Respirator Filtration Test Methods. J. Occup. Environ. Hyg. 2017, 14, 92– 103,  DOI: 10.1080/15459624.2016.1225157
    [Crossref], [PubMed], [CAS], Google Scholar
    26
    A comparison of facemask and respirator filtration test methods
    Rengasamy Samy; Shaffer Ronald; Williams Brandon; Smit Sarah
    Journal of occupational and environmental hygiene (2017), 14 (2), 92-103 ISSN:.
    NIOSH published a Federal Register Notice to explore the possibility of incorporating FDA required filtration tests for surgical masks (SMs) in the 42 CFR Part 84 respirator certification process. There have been no published studies comparing the filtration efficiency test methods used for NIOSH certification of N95 filtering facepiece respirators (N95 FFRs) with those used by the FDA for clearance of SMs. To address this issue, filtration efficiencies of "N95 FFRs" including six N95 FFR models and three surgical N95 FFR models, and three SM models were measured using the NIOSH NaCl aerosol test method, and FDA required particulate filtration efficiency (PFE) and bacterial filtration efficiency (BFE) methods, and viral filtration efficiency (VFE) method. Five samples of each model were tested using each method. Both PFE and BFE tests were done using unneutralized particles as per FDA guidance document. PFE was measured using 0.1 μm size polystyrene latex particles and BFE with ∼3.0 μm size particles containing Staphylococcus aureus bacteria. VFE was obtained using ∼3.0 μm size particles containing phiX 174 as the challenge virus and Escherichia coli as the host. Results showed that the efficiencies measured by the NIOSH NaCl method for "N95 FFRs" were from 98.15-99.68% compared to 99.74-99.99% for PFE, 99.62-99.9% for BFE, and 99.8-99.9% for VFE methods. Efficiencies by the NIOSH NaCl method were significantly (p = <0.05) lower than the other methods. SMs showed lower efficiencies (54.72-88.40%) than "N95 FFRs" measured by the NIOSH NaCl method, while PFE, BFE, and VFE methods produced no significant difference. The above results show that the NIOSH NaCl method is relatively conservative and is able to identify poorly performing filtration devices. The higher efficiencies obtained using PFE, BFE and VFE methods show that adding these supplemental particle penetration methods will not improve respirator certification.
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  27. 27
    Determination of Particulate Filter Efficiency Level for N95 Series Filters Against Solid Particulates for Non-Powdered, Air-Purifying Respirators Standard Testing Procedure (STP); TEB-APR-STP-0059; National Institute for Occupational Safety and Health: Pittsburgh, PA, 2019; pp 1– 9.
    Google Scholar
    There is no corresponding record for this reference.
  28. 28
    Leung, N.; Chu, D.; Shiu, E.; Chan, K.; Mcdevitt, J.; Hau, B.; Yen, H.; Li, Y.; Ip, D.; Peiris, J.; Seto, W.; Leung, G.; Milton, D.; Cowling, B. Respiratory Virus Shedding in Exhaled Breath and Efficacy of Face Masks. Nat. Med. (N. Y., NY, U. S.) 2020, 26, 676– 680,  DOI: 10.1038/s41591-020-0843-2
    [Crossref], [PubMed], [CAS], Google Scholar
    28
    Respiratory virus shedding in exhaled breath and efficacy of face masks
    Leung, Nancy H. L.; Chu, Daniel K. W.; Shiu, Eunice Y. C.; Chan, Kwok-Hung; McDevitt, James J.; Hau, Benien J. P.; Yen, Hui-Ling; Li, Yuguo; Ip, Dennis K. M.; Peiris, J. S. Malik; Seto, Wing-Hong; Leung, Gabriel M.; Milton, Donald K.; Cowling, Benjamin J.
    Nature Medicine (New York, NY, United States) (2020), 26 (5), 676-680CODEN: NAMEFI; ISSN:1078-8956. (Nature Research)
    Abstr.: We identified seasonal human coronaviruses, influenza viruses and rhinoviruses in exhaled breath and coughs of children and adults with acute respiratory illness. Surgical face masks significantly reduced detection of influenza virus RNA in respiratory droplets and coronavirus RNA in aerosols, with a trend toward reduced detection of coronavirus RNA in respiratory droplets. Our results indicate that surgical face masks could prevent transmission of human coronaviruses and influenza viruses from symptomatic individuals.
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  29. 29
    Schiefter, H.; Taft, D.; Porter, J. Effect of Number of Warp and Filling Yarns per Inch and Some Other Elements of Construction on the Properties of Cloth. J. Res. Natl. Bur. Stand. 1936, 16, 139– 147,  DOI: 10.6028/jres.016.004
    [Crossref], Google Scholar
    There is no corresponding record for this reference.
  30. 30
    Mainelis, G.; Willeke, K.; Baron, P.; Grinshpun, S.; Reponen, T. Induction Charging and Electrostatic Classification of Micrometer-Size Particles for Investigating the Electrobiological Properties of Airborne Microorganisms. Aerosol Sci. Technol. 2002, 36, 479– 491,  DOI: 10.1080/027868202753571304
    [Crossref], [CAS], Google Scholar
    30
    Induction charging and electrostatic classification of micrometer-size particles for investigating the electrobiological properties of airborne microorganisms
    Mainelis, Gediminas; Willeke, Klaus; Baron, Paul; Grinshpun, Sergey A.; Reponen, Tiina
    Aerosol Science and Technology (2002), 36 (4), 479-491CODEN: ASTYDQ; ISSN:0278-6826. (Taylor & Francis)
    Our earlier studies have shown that the electrostatic collection technique, a potentially "gentle" bioaerosol collection method, allows for efficient collection of airborne bacteria, but sensitive bacteria such as Pseudomonas fluorescens (P. fluorescens) lose their culturability during collection. We hypothesized that excessive stress was imposed on the sensitive bacteria by the sampler's conventional corona charging mechanism. In this research, we developed and built an exptl. setup that allows us to analyze electrobiol. properties of airborne microorganisms. In this exptl. system, we imparted elec. charges on airborne biol. and nonbiol. particles by aerosolizing them in the presence of an elec. field. The charged P. fluorescens test bacteria and NaCl test particles were then channeled into a parallel plate mobility analyzer, which we have designed so that bacteria and inert particles carrying specific charge ranges can be extd. and made available for further anal. When testing the exptl. system, we related the extd. particle concns. to the total particle concn. and obtained the charge distributions of these particles at different charging conditions. Our results have shown that even without charging, aerosolized P. fluorescens bacteria have a net neg. charge and can carry up to 13,000 elementary charges per bacterium. In contrast, the NaCl particles were found to carry very few elec. charges. We concluded that the elec. charge carried by a bacterium consists of 2 components: its own natural charge, which can be high, and the charge imposed on it by the dispersion process. Our expts. have shown that the charge distributions on biol. and nonbiol. particles can be effectively manipulated by varying the external elec. field during their aerosolization. Since airborne microorganisms may carry high internal elec. charges, their collection by elec. field forces may be possible without first elec. charging them.
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  31. 31
    Willeke, K.; Whitby, K. Atmospheric Aerosols: Size Distribution Interpretation. J. Air Pollut. Control Assoc. 1975, 25, 529– 534,  DOI: 10.1080/00022470.1975.10470110
    [Crossref], Google Scholar
    There is no corresponding record for this reference.
  32. 32
    Chen, C.; Huang, S. The Effects of Particle Charge on the Performance of a Filtering Facepiece. Am. Ind. Hyg. Assoc. J. 1998, 59, 227– 233,  DOI: 10.1080/15428119891010488
    [Crossref], [PubMed], [CAS], Google Scholar
    32
    The effects of particle charge on the performance of a filtering facepiece
    Chen C C; Huang S H
    American Industrial Hygiene Association journal (1998), 59 (4), 227-33 ISSN:0002-8894.
    This study quantitatively determined the effect of electrostatic charge on the performance of an electret filtering facepiece. Monodisperse challenge corn oil aerosols with uniform charges were generated using a modified vibrating orifice monodisperse aerosol generator. The aerosol size distributions and concentrations upstream and downstream of an electret filter were measured using an aerodynamic particle sizer, an Aerosizer, and a scanning mobility particle sizer. The aerosol charge was measured by using an aerosol electrometer. The tested electret filter had a packing density of about 0.08, fiber size of 3 microns, and thickness of 0.75 mm. As expected, the primary filtration mechanisms for the micrometer-sized particles are interception and impaction, especially at high face velocities, while electrostatic attraction and diffusion are the filtration mechanisms for submicrometer-sized aerosol particles. The fiber charge density was estimated to be 1.35 x 10(-5) coulomb per square meter. After treatment with isopropanol, most of fiber charges were removed, causing the 0.3-micron aerosol penetration to increase from 36 to 68%. The air resistance of the filter increased slightly after immersion in the isopropanol, probably due to the coating of impurities in isopropanol. The aerosol penetration decreased with increasing aerosol charge. The most penetrating aerosol size became larger as the aerosol charge increased, e.g., from 0.32 to 1.3 microns when the aerosol charge increased from 0 to 500 elementary charges.
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  33. 33
    Kowalski, W.; Bahnfleth, W.; Whittam, T. Filtration of Airborne Microorganisms: Modeling and Prediction. In AHRAE Transactions, Seattle WA, 06/18/1999–06/23/1999; Geshwiler, M., Harrell, D., Roberson, T., Eds.; American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.: Seattle, WA, 1999; Vol. 4273, pp 4– 17.
    Google Scholar
    There is no corresponding record for this reference.
  34. 34
    Zhou, S.; Lukula, S.; Chiossone, C.; Nims, R.; Suchmann, D.; Ijaz, M. Assessment of a Respiratory Face Mask for Capturing Air Pollutants and Pathogens Including Human Influenza and Rhinoviruses. J. Thorac. Dis. 2018, 10, 2059– 2069,  DOI: 10.21037/jtd.2018.03.103
    [Crossref], [PubMed], [CAS], Google Scholar
    34
    Assessment of a respiratory face mask for capturing air pollutants and pathogens including human influenza and rhinoviruses
    Zhou S Steve; Lukula Salimatu; Chiossone Cory; Suchmann Donna B; Nims Raymond W; Ijaz M Khalid; Ijaz M Khalid
    Journal of thoracic disease (2018), 10 (3), 2059-2069 ISSN:2072-1439.
    BACKGROUND: Prevention of infection with airborne pathogens and exposure to airborne particulates and aerosols (environmental pollutants and allergens) can be facilitated through use of disposable face masks. The effectiveness of such masks for excluding pathogens and pollutants is dependent on the intrinsic ability of the masks to resist penetration by airborne contaminants. This study evaluated the relative contributions of a mask, valve, and Micro Ventilator on aerosol filtration efficiency of a new N95 respiratory face mask. METHODS: The test mask was challenged, using standardized methods, with influenza A and rhinovirus type 14, bacteriophage ΦΧ174, Staphylococcus aureus (S. aureus), and model pollutants. The statistical significance of results obtained for different challenge microbial agents and for different mask configurations (masks with operational or nonoperational ventilation fans and masks with sealed Smart Valves) was assessed. RESULTS: The results demonstrate >99.7% efficiency of each test mask configuration for exclusion of influenza A virus, rhinovirus 14, and S. aureus and >99.3% efficiency for paraffin oil and sodium chloride (surrogates for PM2.5). Statistically significant differences in effectiveness of the different mask configurations were not identified. The efficiencies of the masks for excluding smaller-size (i.e., rhinovirus and bacteriophage ΦΧ174) vs. larger-size microbial agents (influenza virus, S. aureus) were not significantly different. CONCLUSIONS: The masks, with or without features intended for enhancing comfort, provide protection against both small- and large-size pathogens. Importantly, the mask appears to be highly efficient for filtration of pathogens, including influenza and rhinoviruses, as well as the fine particulates (PM2.5) present in aerosols that represent a greater challenge for many types of dental and surgical masks. This renders this individual-use N95 respiratory mask an improvement over the former types of masks for protection against a variety of environmental contaminants including PM2.5 and pathogens such as influenza and rhinoviruses.
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  35. 35
    Lee, S.; Obendorf, S. Statistical Model of Pesticide Penetration through Woven Work Clothing Fabrics. Arch. Environ. Contam. Toxicol. 2005, 49, 266– 273,  DOI: 10.1007/s00244-004-0127-8
    [Crossref], [PubMed], [CAS], Google Scholar
    35
    Statistical Model of Pesticide Penetration Through Woven Work Clothing Fabrics
    Lee, Seungsin; Obendorf, S. Kay
    Archives of Environmental Contamination and Toxicology (2005), 49 (2), 266-273CODEN: AECTCV; ISSN:0090-4341. (Springer Science+Business Media, Inc.)
    Statistical models estg. the level of protection and thermal comfort performance of woven fabrics were developed using simple fabric and liq. parameters. Eighteen woven fabrics were evaluated against three pesticide mixts. of atrazine and pendimethalin at different concns. Using three mixts. that represent a range of both surface tension and viscosity, percentages of pesticide penetration are measured, along with fabric thickness, fabric cover factor, yarn twist factor, yarn packing factor, solid vol. fraction, wicking height, and air permeability. Statistical analyses are performed to examine the relationship between liq./fabric parameters and pesticide penetration. Statistical analyses show that fabric cover factor, yarn twist factor, viscosity of pesticide mixt., crit. surface tension of solid, and wicking height are significant parameters affecting pesticide penetration. For this purpose, cover factor and twist factor are better parameters in describing the geometry of woven fabrics than solid vol. fraction. Modeling of comfort performance of woven fabric based on simple textile parameters shows that the combination of fabric thickness, cover factor, yarn twist factor and yarn packing factor can be used to est. air permeability of woven fabric. These findings could be used for developing selection charts or tools as guidelines for the selection of personal protective equipment for use in hot, humid environments.
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  36. 36
    Zhao, M.; Liao, L.; Xiao, W.; Yu, X.; Wang, H.; Wang, Q.; Lin, Y.; Kilinc-Balci, F.; Price, A.; Chu, L.; Chu, M.; Chu, S.; Cui, Y., Household Materials Selection for Homemade Cloth Face Coverings and Their Filtration Efficiency Enhancement with Triboelectric Charging. Nano Lett. . 2020.  DOI: 10.1021/acs.nanolett.0c02211 .
    [ACS Full Text ACS Full Text], Google Scholar
    There is no corresponding record for this reference.
  37. 37
    Alekseeva, L. Theoretical Aspects of Predicting the Electrostatic Properties of Textile Materials. Fibre Chem. 2007, 39, 225– 226,  DOI: 10.1007/s10692-007-0047-2
    [Crossref], [CAS], Google Scholar
    37
    Theoretical aspects of predicting the electrostatic properties of textile materials
    Alekseeva, L. V.
    Fibre Chemistry (2007), 39 (3), 225-226CODEN: FICYAP; ISSN:0015-0541. (Springer)
    A theor. method was developed for detg. the electrostatic state of different chem. fibers. Math. relations that can be used to det. the elec. capacitance of chem. fibers of different configuration were obtained. The inverse problem was solved - finding the functional dependence of the dielec. const. of the material investigated on the initial capacitance.
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  38. 38
    Žilinskas, P.; Lozovski, T.; Jankauskas, V.; Jurksus, J. Electrostatic Properties and Characterization of Textile Materials Affected by Ion Flux. Mater. Sci.-Polym. 2013, 19, 61– 66,  DOI: 10.5755/j01.ms.19.1.3828
    [Crossref], Google Scholar
    There is no corresponding record for this reference.
  39. 39
    Kadolph, S.; Marcketti, S. Textiles, 12th ed.; Pearson: Boston, MA, 2016; pp 164– 165.
    Google Scholar
    There is no corresponding record for this reference.
  40. 40
    Radney, J.; Zangmeister, C. Comparing Aerosol Refractive Indices Retrieved from Full Distribution and Size- and Mass-Selected Measurements. J. Quant. Spectrosc. Radiat. Transfer 2018, 220, 52– 66,  DOI: 10.1016/j.jqsrt.2018.08.021
    [Crossref], [CAS], Google Scholar
    40
    Comparing aerosol refractive indices retrieved from full distribution and size- and mass-selected measurements
    Radney, James G.; Zangmeister, Christopher D.
    Journal of Quantitative Spectroscopy & Radiative Transfer (2018), 220 (), 52-66CODEN: JQSRAE; ISSN:0022-4073. (Elsevier Ltd.)
    Refractive index retrievals (also termed inverse Mie methods or optical closure) have seen considerable use as a method to ext. the refractive index of aerosol particles from measured optical properties. Retrievals of an aerosol refractive index use one of two primary methods: 1) measurements of the extinction, absorption and/or scattering cross-sections or efficiencies of size- (and mass-) selected particles for mass-mobility refractive index retrievals (MM-RIR) or 2) measurements of aerosol size distributions and a combination of the extinction, absorption and/or scattering coeffs. for full distribution refractive index retrievals (FD-RIR). These two methods were compared in this study using pure and mixts. of ammonium sulfate (AS) and nigrosin aerosol, which constitute a non-absorbing and absorbing material, resp. The results indicate that the retrieved complex refractive index values are correlated to the amt. of nigrosin in the aerosol but can be highly variable with differences in the real and imaginary components that range between -0.002 and 0.216 and -0.013 and 0.086; the av. and std. deviation of the differences are 0.046 ± 0.046 and 0.023 ± 0.033, resp. Forward calcn. of the optical properties yielded av. abs. values of the relative deviation of ≈ 15% and ≈ 26% for FD-RIR data using the MM-RIR values and contrariwise. The range of retrieved refractive indexes were used to calc. the normalized global av. aerosol radiative forcing of a model accumulation mode remote continental aerosol. Deviations using the refractive indexes of the pure materials range from 9% to 32% for AS and 27% to 45% for nigrosin. For mixts. of nigrosin and AS, deviations were all > 100% and not always able to capture the correct direction of the forcing; i.e., pos. vs. neg.
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  41. 41
    Wiedensohler, A. An Approximation of the Bipolar Charge Distribution for Particles in the Submicron Size Range. J. Aerosol Sci. 1988, 19, 387– 389,  DOI: 10.1016/0021-8502(88)90278-9
    [Crossref], [CAS], Google Scholar
    41
    An approximation of the bipolar charge distribution for particles in the submicron size range
    Wiedensohler, A.
    Journal of Aerosol Science (1988), 19 (3), 387-9CODEN: JALSB7; ISSN:0021-8502.
    An empirical equation is proposed which permits rapid calcn. of the bipolar charge distribution for the aerosol size range 1-1000 nm. This equation approximates the distribution calcd. from the N. Fuchs (1963) model.
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  42. 42
    Radney, J.; Ma, X.; Gillis, K.; Zachariah, M.; Hodges, J.; Zangmeister, C. Direct Measurements of Mass-Specific Optical Cross Sections of Single Component Aerosol Mixtures. Anal. Chem. 2013, 85, 8319– 8325,  DOI: 10.1021/ac401645y
    [ACS Full Text ACS Full Text], [CAS], Google Scholar
    42
    Direct Measurements of Mass-Specific Optical Cross Sections of Single-Component Aerosol Mixtures
    Radney, James G.; Ma, Xiaofei; Gillis, Keith A.; Zachariah, Michael R.; Hodges, Joseph T.; Zangmeister, Christopher D.
    Analytical Chemistry (Washington, DC, United States) (2013), 85 (17), 8319-8325CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
    Optical properties of atm. aerosols vary widely, depending on particle compn., morphol., and mixing state. This aerosol diversity and complexity motivates measurement techniques which can discriminate and quantify a variety of single- and multi-component aerosols that are internally and externally mixed. This work presents a new combination of techniques to directly measure mass-specific extinction and absorption cross sections of lab.-generated aerosols relevant to atm. studies. The approach used tandem differential mobility and aerosol particle mass analyzers, cavity ring-down and photoacoustic spectrometers, and a condensation particle counter. This suite of instruments enabled aerosol particle size; mass, extinction, and absorption coeffs.; and aerosol no. d. measurements, resp. Together, these observables yield mass-specific extinction and absorption cross sections without any model particle morphol. or accounting for sample collection artifacts. This was demonstrated in a set of case studies involving complete aerosol sepn. by charge, external mixt. sepn. by mass, and discrimination between particle types by effective d. and single-scattering albedo.
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  43. 43
    Radney, J.; Zangmeister, C. Practical Limitations of Aerosol Separation by a Tandem Differential Mobility Analyzer–Aerosol Particle Mass Analyzer. Aerosol Sci. Technol. 2016, 50, 160– 172,  DOI: 10.1080/02786826.2015.1136733
    [Crossref], [PubMed], [CAS], Google Scholar
    43
    Practical limitations of aerosol separation by a tandem differential mobility analyzer-aerosol particle mass analyzer
    Radney, James G.; Zangmeister, Christopher D.
    Aerosol Science and Technology (2016), 50 (2), 160-172CODEN: ASTYDQ; ISSN:0278-6826. (Taylor & Francis, Inc.)
    A cavity ring-down spectrometer and condensation particle counter were used to investigate the limitations in the sepn. of singly and multiply charged aerosol particles by a tandem differential mobility analyzer (DMA) and aerosol particle mass analyzer (APM). The impact of particle polydispersity and morphol. was investigated using three materials: nearly monodisperse polystyrene latex nanospheres (PSL); polydisperse, nearly spherical ammonium sulfate (AS), and polydisperse lacey fractal soot agglomerates. PSL and AS particles were easily resolved as a function of charge. For soot, the presence of multiply charged particles severely affects the isolation of the singly charged particles. In cases where the DMA-APM was unable to fully resolve the singly charged particles of interest, the peak mass deviated by up to 13% leading to errors in the mass specific extinction cross section of over 100%. For measurements of nonspherical particles, nonsym. distributions of concn. as a function of mass were a sign of the presence of multiply charged particles. Under these conditions, the effects of multiply charged particles can be reduced by using a second charge neutralizer after the DMA and prior to the APM. Diln. of the aerosol stream serves to decrease the total no. concn. of particles and does not remove the contributions of multiply charged particles.
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  44. 44
    Buys, T.; De Clerk, K. Bi-Gaussian Fitting of Skewed Peaks. Anal. Chem. 1972, 44, 1273– 1275,  DOI: 10.1021/ac60315a005
    [ACS Full Text ACS Full Text], [CAS], Google Scholar
    44
    Bi-Gaussian fitting of skewed peaks
    Buys, T. S.; De Clerk, K.
    Analytical Chemistry (1972), 44 (7), 1273-5CODEN: ANCHAM; ISSN:0003-2700.
    The bi-Gaussian fitting function can be used for predicting the zeroth and 1st statistical moments (related to the mass and the thermodynamics of the system, resp.) of asym. chromatogram peaks. The fitting of a Poisson distribution at the peak max. and at half-height with a bi-Gaussian distribution showed that the 2nd and 3rd moments (related to peak width and asymmetry, resp.) of skewed peaks cannot be predicted. The bi-Gaussian function can serve as the basis for a more refined computer anal. of overlapping peaks, and can be used for the empirical prediction of retention times.
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  45. 45
    Determination of Inhalation Resistance TEB-APR-STP-0007; National Institute for Occupational Safety and Health: Pittsburgh, PA, 2019; pp 1– 7.
    Google Scholar
    There is no corresponding record for this reference.
  46. 46
    Determination of Exhalation Resistance TEB-APR-STP-0003; National Institute for Occupational Safety and Health: Pittsburgh, PA, 2019; pp 1– 6.
    Google Scholar
    There is no corresponding record for this reference.
  47. 47
    Chen, C.; Willeke, K. Aerosol Penetration through Surgical Masks. Am. J. Infect. Control 1992, 20, 177– 184,  DOI: 10.1016/S0196-6553(05)80143-9
    [Crossref], [PubMed], [CAS], Google Scholar
    47
    Aerosol penetration through surgical masks
    Chen C C; Willeke K
    American journal of infection control (1992), 20 (4), 177-84 ISSN:0196-6553.
    BACKGROUND: Surgical masks are used in hospitals to reduce postoperative infection in patients. The presence of aerosols containing pathogens makes it desirable to protect the medical staff as well. METHODS: The collection efficiencies of surgical masks measured with two aerosol-size spectrometers. The flow rates through the masks were varied from 5 to 100 L/min to study the flow dependency. For comparison, several industrial-type respirators were also tested. RESULTS: A surgical mask consisting of filter material performed better than did a surgical mask consisting only of a shell with a coarse pore structure. The latter passed 80% of submicrometer-sized aerosols with little flow dependency, whereas the penetration of submicrometer-sized aerosols through the mask made of filter material ranged from 25% at a flow rate of 5 L/min to 70% at 100 L/min. CONCLUSIONS: The mask that has the highest collection efficiency is not necessarily the best mask from the perspective of the filter-quality factor, which considers not only the capture efficiency but also the air resistance. Although surgical mask media may be adequate to remove bacteria exhaled or expelled by health care workers, they may not be sufficient to remove the submicrometer-size aerosols containing pathogens to which these health care workers are potentially exposed.
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  48. 48
    Food and Drugs; Sterilization Wrap, 21CFR880.6850; Food and Drug Administration: Silver Spring, MD, 2020.
    Google Scholar
    There is no corresponding record for this reference.
  49. 49
    Chattopadhyay, S.; Hatton, T.; Rutledge, G. Aerosol Filtration Using Electrospun Cellulose Acetate Fibers. J. Mater. Sci. 2016, 51, 204– 217,  DOI: 10.1007/s10853-015-9286-4
    [Crossref], [CAS], Google Scholar
    49
    Aerosol filtration using electrospun cellulose acetate fibers
    Chattopadhyay, Saptarshi; Hatton, T. Alan; Rutledge, Gregory C.
    Journal of Materials Science (2016), 51 (1), 204-217CODEN: JMTSAS; ISSN:0022-2461. (Springer)
    Aerosol filtration using electrospun cellulose acetate filters with different mean fiber diams. is discussed, and results are compared with those for 2 conventional filter media: glass fiber filter and cellulose acetate microfiber filter. Filter performance was assessed using 2 aerosols, 1 solid (NaCl) and 1 liq. (di-Et hexyl sebacate), under relatively high face velocity (45 cm/s) conditions. Exptl. observations were compared to theor. predictions based on single fiber filtration efficiency. Results indicated mechanisms for single fiber filtration efficiency provide reasonable predictions of the most penetrating particle size (40-270 nm), percentage penetration (0.03-70%), and fiber diam. (0.1-24 μm). Using an anal. based on blocking filtration laws, the authors concluded filtration by cake formation dominated for NaCl aerosols on electrospun filter media; filters with larger fiber diam. exhibited a transition in mechanisms, from an initial regime characterized by pore-blocking to a later regime characterized by cake formation. The liq. aerosol did not exhibit cake formation, even for the smallest fiber diams., and had much a smaller effect on pressure drop than solid aerosols. Electrospun filters demonstrated slightly better quality factors vs. the com. glass fiber filter, at a much lower thickness. Generally, results demonstrated control of the electrospun cellulose acetate fiber properties for air filtration applications.
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  50. 50
    Payen, J.; Vroman, P.; Lewandowski, M.; Perwuelz, A.; Callé-Chazelet, S.; Thomas, D. Influence of Fiber Diameter, Fiber Combinations and Solid Volume Fraction on Air Filtration Properties in Nonwovens. Text. Res. J. 2012, 82, 1948– 1959,  DOI: 10.1177/0040517512449066
    [Crossref], [CAS], Google Scholar
    50
    Influence of fiber diameter, fiber combinations and solid volume fraction on air filtration properties in nonwovens
    Payen, Julien; Vroman, Philippe; Lewandowski, Maryline; Perwuelz, Anne; Calle-Chazelet, Sandrine; Thomas, Dominique
    Textile Research Journal (2012), 82 (19), 1948-1959, 12 pp.CODEN: TRJOA9; ISSN:0040-5175. (Sage Publications Ltd.)
    In air filtration, nonwoven materials are known to be pertinent structures for fine filtration and moderate pressure drop. In order to develop a filter that combines good permeability and high efficiency, it is important to identify the relevant structural parameters of the nonwoven. The main criteria studied in this paper are fiber fineness, solid vol. fraction and basis length (total length of fiber in unit area of nonwoven). The effect of combining different fiber diams. in order to reach the best compromise is also investigated. Our results show that the use of binary blends of different fiber diams. improves overall filtration behavior, in comparison to nonwoven filters with equiv. unimodal diam. distribution. A theor. filtration model is used to predict filtration behavior for different structural characteristics and these predictions are compared to exptl. results. However, this comparison demonstrates the limits of existing models in the case of fiber blends.
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  51. 51
    Hosseini, S.; Tafreshi, H. On the Importance of Fibers’ Cross-Sectional Shape for Air Filters Operating in the Slip Flow Regime. Powder Technol. 2011, 212, 425– 431,  DOI: 10.1016/j.powtec.2011.06.025
    [Crossref], [CAS], Google Scholar
    51
    On the importance of fibers' cross-sectional shape for air filters operating in the slip flow regime
    Hosseini, S. A.; Tafreshi, H. Vahedi
    Powder Technology (2011), 212 (3), 425-431CODEN: POTEBX; ISSN:0032-5910. (Elsevier B.V.)
    In this paper, the effects are studied of fibers cross-sectional shape on the performance of a fibrous filter in the slip and no-slip flow regimes. The slip flow regime is expected to prevail when fiber diam. is comparable in size to the mean free path of the gas mols. (about 65 nm at normal temps. and pressures), whereas the no-slip flow regime describes the aerodynamic condition of flow through media with large fibers. The numerical simulations conducted for flow around single fibers with different geometries indicate that, while the collection efficiency is only weakly affected by the cross-sectional shape of nanofibers, the fiber drag (i.e., permeability of the media) can be considerably influenced by the fiber's shape. Simulating the flow field around nano- and microfibers with circular, square, trilobal, and elliptical cross-sections, it was found that the more streamlined the fiber geometry, the lower the fiber drag caused by a nanofiber relative to that generated by its micron-sized counterpart.
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  52. 52
    Bradow, J.; Davidonis, G. Quantitation of Fiber Quality and the Cotton Production-Processing Interface: A Physiologist’s Perspective. J. Cotton Sci. 2000, 4, 34– 64
    Google Scholar
    There is no corresponding record for this reference.
  53. 53
    Bailey, B. Diameter Relationships of Wool Fibers from Five Breeds of Sheep Raised in South Dakota. J. Agric. Res. 1940, 60, 415– 426
    Google Scholar
    There is no corresponding record for this reference.
  54. 54
    Stobart, R.; Russell, W.; Larsen, S.; Johnson, C.; Kinnison, J. Sources of Variation in Wool Fiber Diameter. J. Anim. Sci. 1986, 62, 1181– 1186,  DOI: 10.2527/jas1986.6251181x
    [Crossref], Google Scholar
    There is no corresponding record for this reference.
  55. 55
    American Sheep Industry Association. Sheep Production Handbook; Sheep Industry Development Program, 1988; wool-13– wool-73.
    Google Scholar
    There is no corresponding record for this reference.
  56. 56
    Grafe, T.; Graham, K. Polymeric Nanofibers and Nanofiber Webs: A New Class of Nonwovens. Int. Nonwovens J. 2003, os-12, 51– 55,  DOI: 10.1177/1558925003os-1200113
    [Crossref], Google Scholar
    There is no corresponding record for this reference.
  57. 57
    Brown, P.; Cox, C. Fibrous Filter Media; Elsevier: Cambridge, MA, 2017; pp 51– 94.
    Google Scholar
    There is no corresponding record for this reference.
  58. 58
    Perumalraj, R. Characterization of Electrostatic Discharge Properties of Woven Fabrics. J. Text. Sci. Eng. 2015, 6, 1– 6,  DOI: 10.4172/2165-8064.1000235
    [Crossref], Google Scholar
    There is no corresponding record for this reference.
  59. 59
    Forsyth, B.; Liu, B.; Romay, F. Particle Charge Distribution Measurement for Commonly Generated Laboratory Aerosols. Aerosol Sci. Technol. 1998, 28, 489– 501,  DOI: 10.1080/02786829808965540
    [Crossref], [CAS], Google Scholar
    59
    Particle charge distribution measurement for commonly generated laboratory aerosols
    Forsyth, Bruce; Liu, Benjamin Y. H.; Romay, Francisco J.
    Aerosol Science and Technology (1998), 28 (6), 489-501CODEN: ASTYDQ; ISSN:0278-6826. (Elsevier Science Inc.)
    An improved particle charge analyzer system has been developed to measure the abs. charge distribution of common generated lab. aerosols. The charge analyzer system consists of an integral cylindrical mobility analyzer used in conjunction with an optical aerosol spectrometer, with computer assisted operation and data redn. The charge analyzer collects aerosol particles over an abs. elec. mobility range from 4.2*10-4 to 400 cm2/(stat · Volt second) and flow rates that can vary from 0.3 to 30 L per min. The charge analyzer has been used to investigate the nature of spray and contact electrification during aerosol generation by measuring the residual charge distribution on the liq. and solid generated particles. In addn., the neutralization of charged particles by bipolar ions also was studied using conventional neutralizers that use ionizing radiation from alpha and beta sources. Charge distribution measurements were performed on alumina dust (Al), Arizona road dust (ARD), potassium chloride (KCl), sodium chloride (NaCl) and di-octyl sebacate (DOS) liq. particles. Aerosol generation devices include a Collison atomizer, a condensation aerosol generator and a fluidized bed dust generator. Our work provides exptl. charge distribution data for comparison with simple models of electrification theory. Exptl. results showed that charge levels of atomized KCl and NaCl particles were high and decreased as the dissolved ion concn. increased. DOS particles generated by evapn.-condensation were both neutral and moderately charged. These conclusions support the existence of a dipole layer at the liq.-gas interface that interacts with dissolved particles and changes their charge state. Alumina and ARD generated by the fluidized bed disperser are highly charged due to strong contact electrification during dispersion. In most cases, the charge on generated aerosols could be reduced to Boltzmann charge equil. conditions by commonly used radioactive neutralizers.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaK1cXjvVGntr4%253D&md5=4b0db764cbe158f5fb488be72a98f16f
  60. 60
    Pusic, T.; Grancaric, A.; Soljacic, I.; Ribitsch, V. The Effect of Mercerisation on the Electrokinetic Potential of Cotton. Color. Technol. 1999, 115, 121– 124,  DOI: 10.1111/j.1478-4408.1999.tb00308.x
    [Crossref], Google Scholar
    There is no corresponding record for this reference.
  61. 61
    Schindelin, J.; Arganda-Carreras, I.; Frise, E.; Kaynig, V.; Longair, M.; Pietzsch, T.; Preibisch, S.; Rueden, C.; Saalfeld, S.; Schmid, B.; Tinevez, J.; White, D.; Hartenstein, V.; Eliceiri, K.; Tomancak, P.; Cardona, A. Fiji: An Open-Source Platform for Biological-Image Analysis. Nat. Methods 2012, 9, 676– 682,  DOI: 10.1038/nmeth.2019
    [Crossref], [PubMed], [CAS], Google Scholar
    61
    Fiji: an open-source platform for biological-image analysis
    Schindelin, Johannes; Arganda-Carreras, Ignacio; Frise, Erwin; Kaynig, Verena; Longair, Mark; Pietzsch, Tobias; Preibisch, Stephan; Rueden, Curtis; Saalfeld, Stephan; Schmid, Benjamin; Tinevez, Jean-Yves; White, Daniel James; Hartenstein, Volker; Eliceiri, Kevin; Tomancak, Pavel; Cardona, Albert
    Nature Methods (2012), 9 (7_part1), 676-682CODEN: NMAEA3; ISSN:1548-7091. (Nature Publishing Group)
    Fiji is a distribution of the popular open-source software ImageJ focused on biol.-image anal. Fiji uses modern software engineering practices to combine powerful software libraries with a broad range of scripting languages to enable rapid prototyping of image-processing algorithms. Fiji facilitates the transformation of new algorithms into ImageJ plugins that can be shared with end users through an integrated update system. We propose Fiji as a platform for productive collaboration between computer science and biol. research communities.
    >> More from SciFinder ®
    https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhtVKnurbJ&md5=ad150521a33367d37a800bee853dd9db
  62. 62
    Rueden, C.; Schindelin, J.; Hiner, M.; Dezonia, B.; Walter, A.; Arena, E.; Eliceiri, K. ImageJ2: ImageJ for the Next Generation of Scientific Image Data. BMC Bioinf. 2017, 18, 1– 26,  DOI: 10.1186/s12859-017-1934-z
    [Crossref], [PubMed], Google Scholar
    There is no corresponding record for this reference.
  63. 63
    Thompson, A.; Taylor, B. Guide for the Use of the International System of Units (SI) 811; National Institute of Standards and Technology: Gaithersburg, MD, 2008; p 90.
    [Crossref], Google Scholar
    There is no corresponding record for this reference.
  64. 64
    Shapiro, S.; Wilk, M. An Analysis of Variance Test for Normality (Complete Samples). Biometrika 1965, 52, 591– 611,  DOI: 10.2307/2333709
    [Crossref], Google Scholar
    There is no corresponding record for this reference.
  65. 65
    Bertrand, C. Graphing Wizardry. Science 2000, 289, 1893– 1894,  DOI: 10.1126/science.289.5486.1894
    [Crossref], Google Scholar
    There is no corresponding record for this reference.

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  13. Kyeongeun Lee, Yeon-Woo Jung, Hanjou Park, Dongmi Kim, Jooyoun Kim. Sequential Multiscale Simulation of a Filtering Facepiece for Prediction of Filtration Efficiency and Resistance in Varied Particulate Scenarios. ACS Applied Materials & Interfaces 2021, 13 (48) , 57908-57920. https://doi.org/10.1021/acsami.1c16850
  14. Sriram S. K S Narayanan, Xudong Wang, Jose Paul, Vladislav Paley, Zijian Weng, Libin Ye, Ying Zhong. Disinfection and Electrostatic Recovery of N95 Respirators by Corona Discharge for Safe Reuse. Environmental Science & Technology 2021, 55 (22) , 15351-15360. https://doi.org/10.1021/acs.est.1c02649
  15. Jinwook Lee, Seojin Jung, Hanjou Park, Jooyoun Kim. Bifunctional ZIF-8 Grown Webs for Advanced Filtration of Particulate and Gaseous Matters: Effect of Charging Process on the Electrostatic Capture of Nanoparticles and Sulfur Dioxide. ACS Applied Materials & Interfaces 2021, 13 (42) , 50401-50410. https://doi.org/10.1021/acsami.1c15734
  16. James G. Radney, Jamie L. Weaver, Edward P. Vicenzi, Matthew E. Staymates, Christopher D. Zangmeister. Filter Inserts Impact Cloth Mask Performance against Nano- to Micro-Sized Particles. ACS Nano 2021, 15 (8) , 12860-12868. https://doi.org/10.1021/acsnano.1c05182
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  18. Hongchen Shen, Zhe Zhou, Haihuan Wang, Mengyang Zhang, Minghao Han, David P. Durkin, Danmeng Shuai, Yun Shen. Development of Electrospun Nanofibrous Filters for Controlling Coronavirus Aerosols. Environmental Science & Technology Letters 2021, 8 (7) , 545-550. https://doi.org/10.1021/acs.estlett.1c00337
  19. Sukrant Dhawan, Pratim Biswas. Aerosol Dynamics Model for Estimating the Risk from Short-Range Airborne Transmission and Inhalation of Expiratory Droplets of SARS-CoV-2. Environmental Science & Technology 2021, 55 (13) , 8987-8999. https://doi.org/10.1021/acs.est.1c00235
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  24. James Malloy, Alberto Quintana, Christopher J. Jensen, Kai Liu. Efficient and Robust Metallic Nanowire Foams for Deep Submicrometer Particulate Filtration. Nano Letters 2021, 21 (7) , 2968-2974. https://doi.org/10.1021/acs.nanolett.1c00050
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  26. Shizhe Lin, Shuixiang Wang, Wei Yang, Shuwen Chen, Zisheng Xu, Xiwei Mo, He Zhou, Jiangjiang Duan, Bin Hu, Liang Huang. Trap-Induced Dense Monocharged Perfluorinated Electret Nanofibers for Recyclable Multifunctional Healthcare Mask. ACS Nano 2021, 15 (3) , 5486-5494. https://doi.org/10.1021/acsnano.1c00238
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  28. Peixin Tang, Zheng Zhang, Ahmed Y El-Moghazy, Nicharee Wisuthiphaet, Nitin Nitin, Gang Sun. Daylight-Induced Antibacterial and Antiviral Cotton Cloth for Offensive Personal Protection. ACS Applied Materials & Interfaces 2020, 12 (44) , 49442-49451. https://doi.org/10.1021/acsami.0c15540
  29. W. Cary Hill, Matthew S. Hull, Robert I. MacCuspie. Testing of Commercial Masks and Respirators and Cotton Mask Insert Materials using SARS-CoV-2 Virion-Sized Particulates: Comparison of Ideal Aerosol Filtration Efficiency versus Fitted Filtration Efficiency. Nano Letters 2020, 20 (10) , 7642-7647. https://doi.org/10.1021/acs.nanolett.0c03182
  30. Ana Rule, Gurumurthy Ramachandran, Kirsten Koehler. Comment on Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks: Questioning Their Findings. ACS Nano 2020, 14 (9) , 10756-10757. https://doi.org/10.1021/acsnano.0c05265
  31. Jason N. Hancock, Michael J. Plumley, Katherine Schilling, Donal Sheets, Lawrence Wilen. Comment on “Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks”. ACS Nano 2020, 14 (9) , 10758-10763. https://doi.org/10.1021/acsnano.0c05827
  32. Scott E. Laengert, Yae Ji Kwon, Joel C. Corbin, Timothy A. Sipkens, Patrick Morkus, Ryan J. LaRue, David R. Latulippe, Catherine M. Clase, Charles-François de Lannoy. Aerosol charge neutralization and its impact on particle filtration efficiency of common face mask materials. Journal of Aerosol Science 2023, 173 , 106189. https://doi.org/10.1016/j.jaerosci.2023.106189
  33. Chuang Zhang, Qiangqiang Zhao, Jie Xia, Jinxin He, Ying Chen, Xia Dong, Ji’an Wei. Polymer-grafted cotton fabrics with high filtration efficiency for reusable personal protective masks. Cellulose 2023, 30 (14) , 9191-9205. https://doi.org/10.1007/s10570-023-05428-w
  34. Priya Garg, Siyan Wang, Jessica M. Oakes, Chiara Bellini, Michael J. Gollner. The effectiveness of filter material for respiratory protection worn by wildland firefighters. Fire Safety Journal 2023, 139 , 103811. https://doi.org/10.1016/j.firesaf.2023.103811
  35. M. Jamali, S. Atri, S. Gautam, A. M. Saleh, H. V. Tafreshi, B. Pourdeyhimi. Macroscale modeling of electrostatically charged facemasks. Aerosol Science and Technology 2023, 57 (7) , 700-711. https://doi.org/10.1080/02786826.2023.2203188
  36. Lei Hua, Ying Wang, Bijuan Mo, Zuqi Guo, Yulei Wang, Zexuan Su, Minqi Huang, Han Chen, Xiaowen Ma, Jiaxin Xie, Mengxian Luo. The hidden inequality: the disparities in the quality of daily use masks associated with family economic status. Frontiers in Public Health 2023, 11 https://doi.org/10.3389/fpubh.2023.1163428
  37. Tomas Solano, Kourosh Shoele, Rajat Mittal. Face masks provide high outward protection despite peripheral leakage: Insights from a reduced-order model of face mask aerodynamics. Physics of Fluids 2023, 35 (6) https://doi.org/10.1063/5.0153513
  38. Peter P. Moschovis, Jesiel Lombay, Jennifer Rooney, Sara R. Schenkel, Dilpreet Singh, Shawheen J. Rezaei, Nora Salo, Amanda Gong, Lael M. Yonker, Jhill Shah, Douglas Hayden, Patricia L. Hibberd, Philip Demokritou, T. Bernard Kinane. The effect of activity and face masks on exhaled particles in children. Pediatric Investigation 2023, 7 (2) , 75-85. https://doi.org/10.1002/ped4.12376
  39. Fangfei Zhang, Junzhu Lin, Mingwan Yang, Yun Wang, Zhicheng Ye, Jiajun He, Jie Shen, Xuechang Zhou, Zhiguang Guo, Yabin Zhang, Ben Wang. High-breathable, antimicrobial and water-repellent face mask for breath monitoring. Chemical Engineering Journal 2023, 466 , 143150. https://doi.org/10.1016/j.cej.2023.143150
  40. Orlane Douguet, Karine Buet-Gautier, Gontrand Leyssens, Marie-Ange Bueno, Daniel Mathieu, Jean-Francois Brilhac, Valérie Tschamber. Evaluation of structural parameters to predict particle filtration and air permeability performance of woven textiles. Textile Research Journal 2023, 54 , 004051752311736. https://doi.org/10.1177/00405175231173601
  41. M. Konstantinov, D. Schmeling, C. Wagner. Numerical simulation of the aerosol formation and spreading in an air-conditioned train compartment. Journal of Aerosol Science 2023, 170 , 106139. https://doi.org/10.1016/j.jaerosci.2023.106139
  42. Simon Berger, Mehdi Azimian, Philipp Eichheimer, Dennis Hoch, Liping Cheng, Jennifer Niessner. Computational Fluid Dynamics‐Based Optimization of Face Mask Filter Media Using Micro‐Computed Tomography Scans. Chemical Engineering & Technology 2023, 46 (5) , 1039-1046. https://doi.org/10.1002/ceat.202200460
  43. Yanqi Dai, Jubair Ahmed, Mohan Edirisinghe. Pressurized Gyration: Fundamentals, Advancements, and Future. Macromolecular Materials and Engineering 2023, 13 https://doi.org/10.1002/mame.202300033
  44. Minthra Chantaso, Kriengkrai Chaiyong, Ratthapong Meesupthong, Naiyasit Yingkamhaeng, Luong Ngoc Diem, Selorm Torgbo, Prakit Sukyai, Somwang Khantayanuwong, Buapan Puangsin, Preeyanuch Srichola. Sugarcane leave-derived cellulose nanocrystal/graphene oxide filter membrane for efficient removal of particulate matter. International Journal of Biological Macromolecules 2023, 234 , 123676. https://doi.org/10.1016/j.ijbiomac.2023.123676
  45. Xue Li, Hao Yang, Ping Zheng, Danmin Lin, Zhijun Zhang, Miaomiao Kang, Dong Wang, Ben Zhong Tang. Aggregation-induced emission materials: a platform for diverse energy transformation and applications. Journal of Materials Chemistry A 2023, 11 (10) , 4850-4875. https://doi.org/10.1039/D2TA09630G
  46. Simon Berger, Marvin Mattern, Jennifer Niessner. Face mask performance related to potentially infectious aerosol particles, breathing mode and facial leakage. International Journal of Hygiene and Environmental Health 2023, 248 , 114103. https://doi.org/10.1016/j.ijheh.2022.114103
  47. Md Al-Amin, Md Tanjim Hossain, Muneeb Tahir, Diana Wyman, S M Fijul Kabir. A Critical Review on Reusable Face Coverings: Mechanism, Development, Factors, and Challenges. Textiles 2023, 3 (1) , 142-162. https://doi.org/10.3390/textiles3010011
  48. Elif Tunç-Songur, Hakan Gölaç, Çiğdem Önen, Tugay Rifat Duyar, Metin Yılmaz, Yusuf Kemal Kemaloğlu. How Does Long Term Use of Surgical Face Mask Affect the Voice in Normophonic Subjects?. Journal of Voice 2023, 395 https://doi.org/10.1016/j.jvoice.2023.02.004
  49. Tunga Salthammer, Heinz‐Jörn Moriske. Airborne infections related to virus aerosol contamination at indoor cultural venues: Recommendations on how to minimize. Public Health Challenges 2023, 2 (1) https://doi.org/10.1002/puh2.59
  50. Prasidha R. Neupane, Iswor Bajracharya, Sunil B. Khatry, . Effectiveness of Inexpensive Cloth Facemasks and Their Amendments to Reduce Ambient Particulate Exposures: A Case of Kathmandu, Nepal. Journal of Environmental and Public Health 2023, 2023 , 1-10. https://doi.org/10.1155/2023/5144345
  51. Rajat Mittal, Kenneth Breuer, Jung Hee Seo. The Flow Physics of Face Masks. Annual Review of Fluid Mechanics 2023, 55 (1) , 193-211. https://doi.org/10.1146/annurev-fluid-120720-035029
  52. Ana Aline Mendes Paim, Morgana Carneiro de Andrade, Fernanda Steffens. The use of textile materials for respiratory protection in times of pandemics: a systematic review and analysis. Research Journal of Textile and Apparel 2023, 5 https://doi.org/10.1108/RJTA-04-2022-0041
  53. Katarina Goodge, Margaret Frey. Cloth Face Coverings: Effect of Decontamination Method on Fabric Performance. AATCC Journal of Research 2023, 10 (1) , 18-27. https://doi.org/10.1177/24723444221132051
  54. Ian A. Carr, Gavin D’Souza, Ming Xu, Shailesh Ozarkar, Daniel Porter, Marc Horner, Prasanna Hariharan. In Silico Fit Evaluation of Additively Manufactured Face Coverings. Annals of Biomedical Engineering 2023, 51 (1) , 34-44. https://doi.org/10.1007/s10439-022-03026-8
  55. Boon Hong Lee, Sook Mei Khor. Medical Waste Biodegradation. 2023, 1173-1209. https://doi.org/10.1007/978-3-031-09710-2_70
  56. Jike Gao, Fawei Li, Shangjun Liu. A Research on the Air Permeability of High Polymer Materials Used to Produce Sports Clothing Fabrics. Fluid Dynamics & Materials Processing 2023, 19 (5) , 1173-1187. https://doi.org/10.32604/fdmp.2022.021140
  57. Igor Tyurin, Salih Tashpulatov, Valery Belgorodsky, Elena Andreeva, , . Mathematical modeling of viscoelastic foam material for design of filtering respirators. E3S Web of Conferences 2023, 371 , 02055. https://doi.org/10.1051/e3sconf/202337102055
  58. Naomichi Yamamoto. Control technologies. 2023, 359-397. https://doi.org/10.1016/B978-0-12-824411-1.00001-6
  59. Maryam Ebrahimiazar, Ladan Eskandarian, Samuele Amadio, Andre Khayat, Nasser Ashgriz, Milad Alizadeh-Meghrazi. Development of reusable cloth mask with nanoparticle filtration efficiency greater than 95%. Aerosol Science and Technology 2022, 56 (12) , 1075-1095. https://doi.org/10.1080/02786826.2022.2130029
  60. Marta Gonçalves, Jin Young Kim, Yeseul Kim, Najaf Rubab, Narina Jung, Takeshi Asai, Sungchan Hong, Byung Mook Weon. Droplet evaporation on porous fabric materials. Scientific Reports 2022, 12 (1) https://doi.org/10.1038/s41598-022-04877-w
  61. Priya Patel, Bindu Kumari Yadav, Gayatri Patel. State-of-the-Art and Projected Developments of Nanofiber Filter Material for Face Mask Against COVID-19. Recent Patents on Nanotechnology 2022, 16 (4) , 262-270. https://doi.org/10.2174/1872210515666210604110946
  62. Timothy A. Sipkens, Joel C. Corbin, Andrew Oldershaw, Gregory J. Smallwood. Particle filtration efficiency measured using sodium chloride and polystyrene latex sphere test methods. Scientific Data 2022, 9 (1) https://doi.org/10.1038/s41597-022-01860-y
  63. Katarina Goodge, Jenny Leigh Du Puis, Mona Maher, Margaret W. Frey, Fatma Baytar, Heeju Park. Cloth face mask fit and function for children part two: Material Selection. Fashion and Textiles 2022, 9 (1) https://doi.org/10.1186/s40691-022-00315-7
  64. Tong Deng, Yifu Chen, Yanbo Liu, Zeren Shang, Junbo Gong. Constructing Janus Microsphere Membranes for Particulate Matter Filtration, Directional Water Vapor Transfer, and High‐Efficiency Broad‐Spectrum Sterilization. Small 2022, 18 (51) https://doi.org/10.1002/smll.202205010
  65. Erik Velasco, Hoang Hieu Ha, Anh Duc Pham, Soheil Rastan. Effectiveness of wearing face masks against traffic particles on the streets of Ho Chi Minh City, Vietnam. Environmental Science: Atmospheres 2022, 2 (6) , 1450-1468. https://doi.org/10.1039/D2EA00071G
  66. Timothy A. Sipkens, Joel C. Corbin, Triantafillos Koukoulas, Andrew Oldershaw, Thierry Lavoie, Jalal Norooz Oliaee, Fengshan Liu, Ian D. Leroux, Gregory J. Smallwood, Prem Lobo, Richard G. Green. Comparison of measurement systems for assessing number- and mass-based particle filtration efficiency. Journal of Occupational and Environmental Hygiene 2022, 19 (10-11) , 629-645. https://doi.org/10.1080/15459624.2022.2114596
  67. Ziheng Pan, Gaohui Liu, Xieyu Chen, Aijaz Ahmed Babar, Yujia Dong, Xianfeng Wang. Water electret charging based polypropylene/electret masterbatch composite melt-blown nonwovens with enhanced charge stability for efficient air filtration. The Journal of The Textile Institute 2022, 113 (10) , 2128-2134. https://doi.org/10.1080/00405000.2021.1969838
  68. Sasan Zahmatkesh, Mika Sillanpää. Review of Method and a New Tool for Decline and Inactive SARS-CoV-2 in Wastewater Treatment. Cleaner Chemical Engineering 2022, 3 , 100037. https://doi.org/10.1016/j.clce.2022.100037
  69. Chaohe Zheng, Haibo Zhao, Haokai Huang, Kun Wang, Haoming Wang. Lattice Boltzmann Simulation of Non-Steady-State Particulate Matter Filtration Process in Woven Fiber. Applied Sciences 2022, 12 (18) , 9219. https://doi.org/10.3390/app12189219
  70. Joelle M. Segovia, Ching-Hsuan Huang, Maxwell Mamishev, Nanhsun Yuan, Jiayang He, Igor Novosselov. Performance of Textile Mask Materials in Varied Humidity: Filtration Efficiency, Breathability, and Quality Factor. Applied Sciences 2022, 12 (18) , 9360. https://doi.org/10.3390/app12189360
  71. Nicola Gartland, David Fishwick, Anna Coleman, Karen Davies, Angelique Hartwig, Sheena Johnson, Martie van Tongeren. Transmission and control of SARS-CoV-2 on ground public transport: A rapid review of the literature up to May 2021. Journal of Transport & Health 2022, 26 , 101356. https://doi.org/10.1016/j.jth.2022.101356
  72. Manabu Nishimura, Yajiao Liu, Masao Gen, Takafumi Seto, Yoshio Otani. Filtration of aerosol particles by parallel and staggered filter arrays. Aerosol Science and Technology 2022, 56 (8) , 767-774. https://doi.org/10.1080/02786826.2022.2080042
  73. Ayman Rezk, Juveiriah M. Ashraf, Wafa Alnaqbi, Sabina Abdul Hadi, Ghada Dushaq, Aisha Alhammadi, Tala El Kukhun, Mahmoud Rasras, Ahmad R. Nusair, Munir Nayfeh, Ammar Nayfeh. Study of Polyethylene Fibers Used in Masks Via Luminescent Aerosolized Silicon Nanoparticles. Silicon 2022, 14 (12) , 6981-6991. https://doi.org/10.1007/s12633-021-01463-z
  74. Yue Pan, Haiqiang Zhang, Zhuolun Niu, Yuting An, Chun Chen. Boundary conditions for exhaled airflow from a cough with a surgical or N95 mask. Indoor Air 2022, 32 (8) https://doi.org/10.1111/ina.13088
  75. Jiyul Lee, Kyeongeun Lee, Hanjou Park, Jooyoun Kim. Environmental storage conditions influencing the filtration behavior of electret filters with repeated use. Journal of Industrial Textiles 2022, 52 , 152808372211194. https://doi.org/10.1177/15280837221119411
  76. Karine Machry, Clóvis W. O. de Souza, Mônica L. Aguiar, André Bernardo. Prevention of pathogen microorganisms at indoor air ventilation system using synthesized copper nanoparticles. The Canadian Journal of Chemical Engineering 2022, 100 (8) , 1739-1746. https://doi.org/10.1002/cjce.24272
  77. Kamilė Kandrotaitė, Vadimas Dudoitis, Ieva Uogintė, Peter Strizak, Francis Pope, Kristina Plauškaitė, Steigvilė Byčenkienė. Study of the aerosol particle filtration efficiency of fabrics used to manufacture non-medical face masks in Lithuania. Lithuanian Journal of Physics 2022, 62 (2) https://doi.org/10.3952/physics.v62i2.4743
  78. Benjarat Jonsirivilai, Selorm Torgbo, Prakit Sukyai. Multifunctional filter membrane for face mask using bacterial cellulose for highly efficient particulate matter removal. Cellulose 2022, 29 (11) , 6205-6218. https://doi.org/10.1007/s10570-022-04641-3
  79. Qiaoqiao Wang, Jianwei Gu, Taicheng An. The emission and dynamics of droplets from human expiratory activities and COVID-19 transmission in public transport system: A review. Building and Environment 2022, 219 , 109224. https://doi.org/10.1016/j.buildenv.2022.109224
  80. Shama Sadaf, Komal Hassan, Ayesha Saeed, Zeeshan Ahmad, Hodaa Usama Abdus Samad. Production of antimicrobial, natural, and reusable material for stitching eco-friendly, extra-protective face masks. International Journal of Clothing Science and Technology 2022, 34 (4) , 566-576. https://doi.org/10.1108/IJCST-05-2021-0075
  81. V. Faye McNeill. Airborne Transmission of SARS-CoV-2: Evidence and Implications for Engineering Controls. Annual Review of Chemical and Biomolecular Engineering 2022, 13 (1) , 123-140. https://doi.org/10.1146/annurev-chembioeng-092220-111631
  82. Max Fraenkl, Milos Krbal, Jakub Houdek, Zuzana Olmrova Zmrhalova, Borivoj Prokes, Petr Hejda, Stanislav Slang, Jan Prikryl, Jakub Ondracek, Otakar Makes, Juraj Kostyk, Petr Nasadil, Pavel Malcik, Vladimir Zdimal, Miroslav Vlcek, . High-quality and easy-to-regenerate personal filter. PLOS ONE 2022, 17 (6) , e0268542. https://doi.org/10.1371/journal.pone.0268542
  83. Joshua F. Robinson, Ioatzin Rios de Anda, Fergus J. Moore, Florence K. A. Gregson, Jonathan P. Reid, Lewis Husain, Richard P. Sear, C. Patrick Royall. How effective are face coverings in reducing transmission of COVID-19?. Aerosol Science and Technology 2022, 56 (6) , 473-487. https://doi.org/10.1080/02786826.2022.2042467
  84. Tomas Solano, Kourosh Shoele. Investigation of the Role of Face Shape on the Flow Dynamics and Effectiveness of Face Masks. Fluids 2022, 7 (6) , 209. https://doi.org/10.3390/fluids7060209
  85. Ashley Lindsay Quigley, Mallory Trent, Holly Seale, Abrar Ahmad Chughtai, C Raina MacIntyre. Cross-sectional survey of changes in knowledge, attitudes and practice of mask use in Sydney and Melbourne during the 2020 COVID-19 pandemic. BMJ Open 2022, 12 (6) , e057860. https://doi.org/10.1136/bmjopen-2021-057860
  86. Shuo Wang, Yuan Liu, Mengmeng Xu, Fei Hu, Qianqian Yu, Linge Wang. Polymersomes as virus-surrogate particles for evaluating the performance of air filter materials. Giant 2022, 10 , 100104. https://doi.org/10.1016/j.giant.2022.100104
  87. Guangjian Tian, Zongwang Huang, Haidong Wang, Chunhong Cui, Yi Zhang. Polycaprolactone nanofiber membrane modified with halloysite and ZnO for anti-bacterial and air filtration. Applied Clay Science 2022, 223 , 106512. https://doi.org/10.1016/j.clay.2022.106512
  88. Zixin He, Qiman Gao, Anna Henley, Zovinar Der Khatchadourian, Wendy Somerville, Michael Wiseman, Luc Mongeau, Faleh Tamimi. Efficacy of aerosol reduction measures for dental aerosol generating procedures. Aerosol Science and Technology 2022, 56 (5) , 413-424. https://doi.org/10.1080/02786826.2022.2040729
  89. Ümit Çelik, Haluk Eren. An approach to compare performance of surgical masks for fighting against the COVID-19 pandemic. Aerosol Science and Technology 2022, 56 (5) , 434-445. https://doi.org/10.1080/02786826.2022.2039589
  90. Clémentine Hyvrard, Margaux Petitjean, Maxime Fieux, Françoise Zerah, André Coste, Sophie Bartier. Covid-19 outbreak: does the use of a surgical mask impact the sense of smell?. Acta Oto-Laryngologica 2022, 142 (5) , 425-430. https://doi.org/10.1080/00016489.2022.2071462
  91. Ziao Wang, Yao Xu, Rulin Liu, Xi Zhu. The 3D-Printing-Accelerated Design for a Biodegradable Respirator from Tree Leaves (TRespirator). Polymers 2022, 14 (9) , 1681. https://doi.org/10.3390/polym14091681
  92. Mudasir Akbar Shah, Bilal Masood Pirzada, Gareth Price, Abel L. Shibiru, Ahsanulhaq Qurashi. Applications of nanotechnology in smart textile industry: A critical review. Journal of Advanced Research 2022, 38 , 55-75. https://doi.org/10.1016/j.jare.2022.01.008
  93. Gautham Vadlamudi, S. K. Thirumalaikumaran, Dipshikha Chakravortty, Abhishek Saha, Saptarshi Basu. Penetration and aerosolization of cough droplet spray through face masks: A unique pathway of transmission of infection. Physics of Fluids 2022, 34 (5) https://doi.org/10.1063/5.0093297
  94. Tomas Solano, Chuanxin Ni, Rajat Mittal, Kourosh Shoele. Perimeter leakage of face masks and its effect on the mask's efficacy. Physics of Fluids 2022, 34 (5) https://doi.org/10.1063/5.0086320
  95. Anton Molina, Pranav Vyas, Nikita Khlystov, Shailabh Kumar, Anesta Kothari, Dave Deriso, Zhiru Liu, Samhita Banavar, Eliott Flaum, Manu Prakash, . Low cost centrifugal melt spinning for distributed manufacturing of non-woven media. PLOS ONE 2022, 17 (4) , e0264933. https://doi.org/10.1371/journal.pone.0264933
  96. Rachel K. Redmann, Brandon J. Beddingfield, Skye Spencer, Nicole R. Chirichella, Julian L. Henley, Wes Hager, Chad J. Roy. A Miniaturized Electrostatic Precipitator Respirator Effectively Removes Ambient SARS-CoV-2 Bioaerosols. Viruses 2022, 14 (4) , 765. https://doi.org/10.3390/v14040765
  97. Lucas Nascimento de Lima, Daniel Costa Reis, Victor Keniti Sakano, Marco Aurélio Franco, Fernando Gonçalves Morais, Vanderley Moacyr John. Influence of microstructure and physical characteristics in the performance of non-professional masks sold in São Paulo. Public Health 2022, 205 , 90-98. https://doi.org/10.1016/j.puhe.2022.01.009
  98. Shivani Tiwari, Subhavna Juneja, Anujit Ghosal, Nandika Bandara, Raju Khan, Scott L. Wallen, Seeram Ramakrishna, Ajeet Kaushik. Antibacterial and antiviral high-performance nanosystems to mitigate new SARS-CoV-2 variants of concern. Current Opinion in Biomedical Engineering 2022, 21 , 100363. https://doi.org/10.1016/j.cobme.2021.100363
  99. Ioatzin Rios de Anda, Jake W. Wilkins, Joshua F. Robinson, C. Patrick Royall, Richard P. Sear. Modeling the filtration efficiency of a woven fabric: The role of multiple lengthscales. Physics of Fluids 2022, 34 (3) https://doi.org/10.1063/5.0074229
  100. Vinicius M. Mello, Cristiane M. Eller, Andreza L. Salvio, Felipe F. Nascimento, Camila M. Figueiredo, Emanuelle S. R. F. Silva, Paulo S. F. Sousa, Pamela F. Costa, Anne A. P. Paiva, Maria A. M. M. Mares-Guias, Elba R. S. Lemos, Marco A. P. Horta, . Effectiveness of face masks in blocking the transmission of SARS-CoV-2: A preliminary evaluation of masks used by SARS-CoV-2-infected individuals. PLOS ONE 2022, 17 (2) , e0264389. https://doi.org/10.1371/journal.pone.0264389
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  • Abstract

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    Figure 1

    Figure 1. Transmitted light imagery of nonwoven and woven face mask materials. (A1–3) Outer, intermediate, and inner layers of a N95 mask showing randomly oriented spun-bond (A1) and melt-blown (A2 and A3) synthetic fibers. (34) (B1,2) Outer and inner surfaces of poplin weave cotton fibers in lightweight flannel (sample Cotton 10). Note: Transmitted light grayscale intensities have been inverted so fibers appear lighter relative to voids; all scale bars represent 1 mm with subsections of 200 μm in length.

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    Figure 2

    Figure 2. Measured filtration efficiency (FE) as a function of particle mobility diameter (Dm) for an N95 respirator (black), the N95 base fabric (orange), a surgical mask (pink), and a twill (blue). The solid bold lines and circles represent the base sample, while the dashed light lines and squares correspond to the reneutralized samples. Olive triangles correspond to the twill FE measured with an aerosol particle mass analyzer and reneutralization. Uncertainties in FE are ±5%. See discussion in text. Corresponding distributions of NU and ND can be found in Section S3 of the Supporting Information.

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    Figure 3

    Figure 3. Filtration efficiency (FE) as a function of number of fabric layers for a cotton fiber poplin weave in a lightweight flannel (Cotton 10). (A) Particle number densities per volume of air for the upstream (NU, black) and downstream (ND) particle counters as a function of number of layers (colored lines). Shown NU was measured for a one-layer sample but was representative of the NU measured for all samples. (B) Calculated FE as a function of Dm and number of layers (colored lines). (C) Measured differential pressure (ΔP, Pa) across the material as a function of number of fabric layers. Gray line and plot maximum correspond to NIOSH recommended maximum differential pressure across filter mask for exhaling (245.2 Pa, 25 mm H2O) and inhaling (343.25 Pa, 35 mm H2O), respectively. (27,45) (D) Minimum measured FEmin as a function of number of layers. (E) Quality factor (QF) as a function of number of fabric layers. Horizontal line shows QF = 3 (WHO recommendation). (3) (F) Maximum penetrating particle size (MPPS, nm) as a function of number of fabric layers. Lines in B correspond to bi-Gaussian fits of the data, while lines in C and D are shown to guide the eye.

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    Figure 4

    Figure 4. Measured samples categorized by type from left to right: cotton (orange), synthetic (pink), synthetic blend (blue), synthetic/cotton blend (olive), paper (green), and polypropylene-based (light orange). (A) Yarn mass (mg yarn–1), (B) differential pressure across sample (ΔP, Pa), (C) minimum filtration efficiency (FEmin, %), (D) quality factor, QF (kPa–1). The average most penetrating particle size (Dm) across all samples was 252 ± 45 nm with individual values plotted in Figure S5. Uncertainties in B and C are ±4.9 Pa (2× manometer read uncertainty) and ±5% (expanded uncertainty), while uncertainties in D were propagated from B and C. Abbreviations: Polyester (poly) and Cotton (Cott).

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    Figure 5

    Figure 5. Comparison of ΔP, FEmin, and QF for single component layers and mixed layered materials. Samples and mixed samples are coordinated by color. (A) Top 3 samples are single layers and bottom 4 are mixtures using fabric samples either similar, or identical to those reported in Konda et al. (2020). (15) Samples marked with ∗ were rubbed together for 30 s while wearing latex gloves to aid in sample charging as in Zhao et al. (2020). (36) Pink diamonds show data from Konda et al. (2020). (15) (B) Top 3 samples are single layers and bottom 2 are mixtures using fabric samples exclusive to this investigation.

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    Figure 6

    Figure 6. Transmitted light images of top performing fabrics based on FEmin and ΔP that fall within NIOSH guidelines and are listed in Table 1: (A) Cotton 8 (hand towel, 100% cotton, block weave), (B1, B2) outer and inner surfaces of Cotton 10 (light flannel, poplin weave, 100% cotton), respectively, (C) Polyester 5 (apparel fabric, poplin weave, 100% polyester), (D) Cotton 6 (inner surface, pillowcase, 100% cotton, satin weave, see SI for image of other side), and (E) Polyester 2 (soft spun, 100% polyester, plain weave). Note: Transmitted light grayscale intensities have been inverted so fibers appear lighter relative to voids; all scale bars represent 1 mm with subsections of 200 μm in length.

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    This article references 65 other publications.

    1. 1
      Health Emergencies Preparedness and Response Team. Advice on the Use of Masks in the Context of COVID-19: Interim Guidance, 6 April 2020, 2020. Advice on the Use of Masks in the Context of COVID-19: Interim Guidance; WHO, 2020. https://apps.who.int/iris/handle/10665/331693 (accessed 06-23-2020).
      Google Scholar
      There is no corresponding record for this reference.
    2. 2
      United States Centers for Disease Control and Prevention. Coronavirus Disease 2019 (COVID-2019); CDC, 2020. https://www.cdc.gov/coronavirus/ (accessed 06-23-2020).
      Google Scholar
      There is no corresponding record for this reference.
    3. 3
      Health Emergencies Preparedness and Response Team. Advice on the Use of Masks in the Context of COVID-19: Interim Guidance, 5 June 2020; WHO, 2020. https://www.who.int/publications/i/item/advice-on-the-use-of-masks-the-community-during-home-care-and-in-health-care-settings-in-the-context-of-the-novel-coronavirus-(2019-ncov)-outbreak (accessed 06-23-2020).
      Google Scholar
      There is no corresponding record for this reference.
    4. 4
      Neuman, B.; Adair, B.; Yoshioka, C.; Quispe, J.; Orca, G.; Kuhn, P.; Milligan, R.; Yeager, M.; Buchmeier, M. Supramolecular Architecture of Severe Acute Respiratory Syndrome Coronavirus Revealed by Electron Cryomicroscopy. J. Virol. 2006, 80, 7918– 7928,  DOI: 10.1128/JVI.00645-06
      [Crossref], [PubMed], [CAS], Google Scholar
      4
      Supramolecular architecture of severe acute respiratory syndrome coronavirus revealed by electron cryomicroscopy
      Neuman, Benjamin W.; Adair, Brian D.; Yoshioka, Craig; Quispe, Joel D.; Orca, Gretchen; Kuhn, Peter; Milligan, Ronald A.; Yeager, Mark; Buchmeier, Michael J.
      Journal of Virology (2006), 80 (16), 7918-7928CODEN: JOVIAM; ISSN:0022-538X. (American Society for Microbiology)
      Coronavirus particles are enveloped and pleomorphic and are thus refractory to crystn. and symmetry-assisted reconstruction. A novel methodol. of single-particle image anal. was applied to selected virus features to obtain a detailed model of the oligomeric state and spatial relationships among viral structural proteins. Two-dimensional images of the S, M, and N structural proteins of severe acute respiratory syndrome coronavirus and two other coronaviruses were refined to a resoln. of ∼4 nm. Proteins near the viral membrane were arranged in overlapping lattices surrounding a disordered core. Trimeric glycoprotein spikes were in register with four underlying ribonucleoprotein densities. However, the spikes were dispensable for ribonucleoprotein lattice formation. The ribonucleoprotein particles displayed coiled shapes when released from the viral membrane. Our results contribute to the understanding of the assembly pathway used by coronaviruses and other pleomorphic viruses and provide the first detailed view of coronavirus ultrastructure.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28Xot1yrtr0%253D&md5=aa64ccff2765ad96e37fdcfa9aa90fd5
    5. 5
      Liu, Y.; Ning, Z.; Chen, Y.; Guo, M.; Liu, Y.; Gali, N. K.; Sun, L.; Duan, Y.; Cai, J.; Westerdahl, D.; Liu, X.; Xu, K.; Ho, K.; Kan, H.; Fu, Q.; Lan, K. Aerodynamic Analysis of SARS-COV-2 in Two Wuhan Hospitals. Nature 2020, 582, 557– 560,  DOI: 10.1038/s41586-020-2271-3
      [Crossref], [PubMed], [CAS], Google Scholar
      5
      Aerodynamic analysis of SARS-CoV-2 in two Wuhan hospitals
      Liu, Yuan; Ning, Zhi; Chen, Yu; Guo, Ming; Liu, Yingle; Gali, Nirmal Kumar; Sun, Li; Duan, Yusen; Cai, Jing; Westerdahl, Dane; Liu, Xinjin; Xu, Ke; Ho, Kin-fai; Kan, Haidong; Fu, Qingyan; Lan, Ke
      Nature (London, United Kingdom) (2020), 582 (7813), 557-560CODEN: NATUAS; ISSN:0028-0836. (Nature Research)
      The ongoing outbreak of coronavirus disease 2019 (COVID-19) has spread rapidly on a global scale. Although it is clear that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is transmitted through human respiratory droplets and direct contact, the potential for aerosol transmission is poorly understood. We investigated the aerodynamic nature of SARS-CoV-2 by measuring viral RNA in aerosols in different areas of 2 Wuhan hospitals during the outbreak of COVID-19 in Feb. and March 2020. The concn. of SARS-CoV-2 RNA in aerosols that was detected in isolation wards and ventilated patient rooms was very low, but it was higher in the toilet areas used by the patients. Levels of airborne SARS-CoV-2 RNA in the most public areas was undetectable, except in 2 areas that were prone to crowding; this increase was possibly due to individuals infected with SARS-CoV-2 in the crowd. Some medical staff areas initially had high concns. of viral RNA with aerosol size distributions that showed peaks in the submicrometer and(or) supermicrometer regions; however, these levels were reduced to undetectable levels after implementation of rigorous sanitization procedures. Although we have not established the infectivity of the virus detected in these hospital areas, we propose that SARS-CoV-2 may have the potential to be transmitted through aerosols. Our results indicate that room ventilation, open space, sanitization of protective apparel, and proper use and disinfection of toilet areas can effectively limit the concn. of SARS-CoV-2 RNA in aerosols. Future work should explore the infectivity of aerosolized virus.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhtF2jurrF&md5=5add7e488d90b75a487adf6b9f8ce97d
    6. 6
      Prather, K.; Wang, C.; Schooley, R. Reducing Transmission of SARS-COV-2. Science 2020, 368, 1422– 1424,  DOI: 10.1126/science.abc6197
      [Crossref], [PubMed], [CAS], Google Scholar
      6
      Reducing transmission of SARS-CoV-2
      Prather, Kimberly A.; Wang, Chia C.; Schooley, Robert T.
      Science (Washington, DC, United States) (2020), 368 (6498), 1422-1424CODEN: SCIEAS; ISSN:1095-9203. (American Association for the Advancement of Science)
      A review. Respiratory infections occur through the transmission of virus-contg. droplets (>5 to 10μm) and aerosols (≤5μm) exhaled from infected individuals during breathing, speaking, coughing, and sneezing. Traditional respiratory disease control measures are designed to reduce transmission by droplets produced in the sneezes and coughs of infected individuals. However, a large proportion of the spread of coronavirus disease 2019 (COVID-19) appears to be occurring through airborne transmission of aerosols produced by asymptomatic individuals during breathing and speaking . Aerosols can accumulate, remain infectious in indoor air for hours, and be easily inhaled deep into the lungs. For society to resume, measures designed to reduce aerosol transmission must be implemented, including universal masking and regular, widespread testing to identify and isolate infected asymptomatic individuals.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXht1CltbzP&md5=34e0ab09e84afb931076bd1af2b0c771
    7. 7
      Milton, D.; Fabian, M.; Angel, M.; Perez, D.; Mcdevitt, J. Influenza Virus Aerosols in Human Exhaled Breath: Particle Size, Culturability, and Effect of Surgical Masks. PLoS Pathog. 2010, 9, e1003205  DOI: 10.1371/journal.ppat.1003205
      [Crossref], Google Scholar
      There is no corresponding record for this reference.
    8. 8
      Weaver, G. Droplet Infection and Its Prevention by the Face Mask. J. Infect. Dis. 1919, 24, 218– 230,  DOI: 10.1093/infdis/24.3.218
      [Crossref], Google Scholar
      There is no corresponding record for this reference.
    9. 9
      Kellogg, W.; Macmillan, G. An Experimental Study of the Efficacy of Gauze Face Masks. Am. J. Public Health 1920, 10, 34– 42,  DOI: 10.2105/AJPH.10.1.34
      [Crossref], [CAS], Google Scholar
      9
      AN EXPERIMENTAL STUDY OF THE EFFICACY OF GAUZE FACE MASKS
      Kellogg W H; Macmillan G
      American journal of public health (New York, N.Y. : 1912) (1920), 10 (1), 34-42 ISSN:0271-4353.
      Masks have not been proved efficient enough to warrant compulsory application for the checking of epidemics, according to Dr. Kellogg, who has conducted a painstaking investigation with gauzes. This investigation is scientific in character, omitting no one of the necessary factors. It ought to settle the much argued question of masks for the public.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BD1c%252FislyhsA%253D%253D&md5=8268103a7b35c2bd7ae59deba857705b
    10. 10
      Rengasamy, S.; Eimer, B.; Shaffer, R. Simple Respiratory Protection-Evaluation of the Filtration Performance of Cloth Masks and Common Fabric Materials against 20–1000 nm Size Particles. Ann. Occup. Hyg. 2010, 54, 789– 798,  DOI: 10.1093/annhyg/meq044
      [Crossref], [PubMed], [CAS], Google Scholar
      10
      Simple Respiratory Protection-Evaluation of the Filtration Performance of Cloth Masks and Common Fabric Materials Against 20-1000 nm Size Particles
      Rengasamy, Samy; Eimer, Benjamin; Shaffer, Ronald E.
      Annals of Occupational Hygiene (2010), 54 (7), 789-798CODEN: AOHYA3; ISSN:0003-4878. (Oxford University Press)
      A shortage of disposable filtering facepiece respirators can be expected during a pandemic respiratory infection such as influenza A. Some individuals may want to use common fabric materials for respiratory protection because of shortage or affordability reasons. To address the filtration performance of common fabric materials against nano-size particles including viruses, five major categories of fabric materials including sweatshirts, T-shirts, towels, scarves, and cloth masks were tested for polydisperse and monodisperse aerosols (20-1000 nm) at two different face velocities (5.5 and 16.5 cm s-1) and compared with the penetration levels for N95 respirator filter media. The results showed that cloth masks and other fabric materials tested in the study had 40-90% instantaneous penetration levels against polydisperse NaCl aerosols employed in the National Institute for Occupational Safety and Health particulate respirator test protocol at 5.5 cm s-1. Similarly, varying levels of penetrations (9-98%) were obtained for different size monodisperse NaCl aerosol particles in the 20-1000 nm range. The penetration levels of these fabric materials against both polydisperse and monodisperse aerosols were much higher than the penetrations for the control N95 respirator filter media. At 16.5 cm s-1 face velocity, monodisperse aerosol penetrations slightly increased, while polydisperse aerosol penetrations showed no significant effect except one fabric mask with an increase. Results obtained in the study show that common fabric materials may provide marginal protection against nanoparticles including those in the size ranges of virus-contg. particles in exhaled breath.
      >> More from SciFinder ®
      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXhtlSgsLnE&md5=28c81fffe6bc548322e0615ab37ba9c9
    11. 11
      Shakya, K.; Noyes, A.; Kallin, R.; Peltier, R. Evaluating the Efficacy of Cloth Facemasks in Reducing Particulate Matter Exposure. J. Exposure Sci. Environ. Epidemiol. 2017, 27, 352– 357,  DOI: 10.1038/jes.2016.42
      [Crossref], [PubMed], [CAS], Google Scholar
      11
      Evaluating the efficacy of cloth facemasks in reducing particulate matter exposure
      Shakya, Kabindra M.; Noyes, Alyssa; Kallin, Randa; Peltier, Richard E.
      Journal of Exposure Science & Environmental Epidemiology (2017), 27 (3), 352-357CODEN: JESEBS; ISSN:1559-0631. (Nature Publishing Group)
      Inexpensive cloth masks are widely used in developing countries to protect from particulate pollution albeit limited data on their efficacy exists. This study examd. the efficiency of four types of masks (three types of cloth masks and one type of surgical mask) commonly worn in the developing world. Five monodispersed aerosol sphere size (30, 100, and 500 nm, and 1 and 2.5 μm) and dild. whole diesel exhaust was used to assess facemask performance. Among the three cloth mask types, a cloth mask with an exhaust valve performed best with filtration efficiency of 80-90% for the measured polystyrene latex (PSL) particle sizes. Two styles of com. available fabric masks were the least effective with a filtration efficiency of 39-65% for PSL particles, and they performed better as the particle size increased. When the cloth masks were tested against lab-generated whole diesel particles, the filtration efficiency for three particle sizes (30, 100, and 500 nm) ranged from 15% to 57%. Std. N95 mask performance was used as a control to compare the results with cloth masks, and our results suggest that cloth masks are only marginally beneficial in protecting individuals from particles <2.5 μm. Compared with cloth masks, disposable surgical masks are more effective in reducing particulate exposure.
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    12. 12
      Davies, A.; Thompson, K.; Giri, K.; Kafatos, G.; Walker, J.; Bennett, A. Testing the Efficacy of Homemade Masks: Would They Protect in an Influenza Pandemic?. Disaster Med. Public Health Prep 2013, 7, 413– 418,  DOI: 10.1017/dmp.2013.43
      [Crossref], [PubMed], [CAS], Google Scholar
      12
      Testing the efficacy of homemade masks: would they protect in an influenza pandemic?
      Davies Anna; Thompson Katy-Anne; Giri Karthika; Kafatos George; Walker Jimmy; Bennett Allan
      Disaster medicine and public health preparedness (2013), 7 (4), 413-8 ISSN:.
      OBJECTIVE: This study examined homemade masks as an alternative to commercial face masks. METHODS: Several household materials were evaluated for the capacity to block bacterial and viral aerosols. Twenty-one healthy volunteers made their own face masks from cotton t-shirts; the masks were then tested for fit. The number of microorganisms isolated from coughs of healthy volunteers wearing their homemade mask, a surgical mask, or no mask was compared using several air-sampling techniques. RESULTS: The median-fit factor of the homemade masks was one-half that of the surgical masks. Both masks significantly reduced the number of microorganisms expelled by volunteers, although the surgical mask was 3 times more effective in blocking transmission than the homemade mask. CONCLUSION: Our findings suggest that a homemade mask should only be considered as a last resort to prevent droplet transmission from infected individuals, but it would be better than no protection.
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    13. 13
      Lai, A.; Poon, C.; Cheung, A. Effectiveness of Facemasks to Reduce Exposure Hazards for Airborne Infections among General Populations. J. R. Soc., Interface 2012, 9, 938– 948,  DOI: 10.1098/rsif.2011.0537
      [Crossref], [PubMed], [CAS], Google Scholar
      13
      Effectiveness of facemasks to reduce exposure hazards for airborne infections among general populations
      Lai A C K; Poon C K M; Cheung A C T
      Journal of the Royal Society, Interface (2012), 9 (70), 938-48 ISSN:.
      Facemasks are widely used as a protective measure by general public to prevent inhalation of airborne pathogens including seasonal, swine and other forms of influenza and severe acute respiratory syndrome (SARS), etc. However, scientific data on effectiveness of facemasks in reducing infections in the community are extremely limited and even inconsistent. In this work, two manikins labelled as 'source' and 'susceptible' were used to measure the protection provided by facemasks under various emission scenarios. The source was modified to generate polydisperse ultrafine particles, whereas the susceptible was modified to mimic a realistic breathing pattern. The facemask was challenged by both pseudo-steady and highly transient emissions generated by an expiratory process where parameters, such as separation distance between manikins, emission velocity and expiratory duration, were controlled and measured systematically. Performances of four different types of facemask fits, varying from ideal to normal wearing practice, were also investigated. Under the pseudo-steady concentration environment, facemask protection was found to be 45 per cent, while under expiratory emissions, protection varied from 33 to 100 per cent. It was also observed that the separation between the source and the manikin was the most influential parameter affecting facemask protection.
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    14. 14
      Van Der Sande, M.; Teunis, P.; Sabel, R. Professional and Home-Made Face Masks Reduce Exposure to Respiratory Infections among the General Population. PLoS One 2008, 3, e2618  DOI: 10.1371/journal.pone.0002618
      [Crossref], [PubMed], Google Scholar
      There is no corresponding record for this reference.
    15. 15
      Konda, A.; Prakash, A.; Moss, G.; Schmoldt, M.; Grant, G.; Guha, S. Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks. ACS Nano 2020, 14, 6339– 6347,  DOI: 10.1021/acsnano.0c03252
      [ACS Full Text ACS Full Text], [CAS], Google Scholar
      15
      Aerosol Filtration Efficiency of Common Fabrics Used in Respiratory Cloth Masks
      Konda, Abhiteja; Prakash, Abhinav; Moss, Gregory A.; Schmoldt, Michael; Grant, Gregory D.; Guha, Supratik
      ACS Nano (2020), 14 (5), 6339-6347CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)
      The emergence of a pandemic affecting the respiratory system can result in a significant demand for face masks. This includes the use of cloth masks by large sections of the public, as can be seen during the current global spread of COVID-19. However, there is limited knowledge available on the performance of various commonly available fabrics used in cloth masks. Importantly, there is a need to evaluate filtration efficiencies as a function of aerosol particulate sizes in the 10 nm to 10μm range, which is particularly relevant for respiratory virus transmission. We have carried out these studies for several common fabrics including cotton, silk, chiffon, flannel, various synthetics, and their combinations. Although the filtration efficiencies for various fabrics when a single layer was used ranged from 5 to 80% and 5 to 95% for particle sizes of <300 nm and >300 nm, resp., the efficiencies improved when multiple layers were used and when using a specific combination of different fabrics. Filtration efficiencies of the hybrids (such as cotton-silk, cotton-chiffon, cotton-flannel) was >80% (for particles <300 nm) and >90% (for particles >300 nm). We speculate that the enhanced performance of the hybrids is likely due to the combined effect of mech. and electrostatic-based filtration. Cotton, the most widely used material for cloth masks performs better at higher weave densities (i.e., thread count) and can make a significant difference in filtration efficiencies. Our studies also imply that gaps (as caused by an improper fit of the mask) can result in over a 60% decrease in the filtration efficiency, implying the need for future cloth mask design studies to take into account issues of "fit" and leakage, while allowing the exhaled air to vent efficiently. Overall, we find that combinations of various commonly available fabrics used in cloth masks can potentially provide significant protection against the transmission of aerosol particles.
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    16. 16
      Macintyre, C.; Seale, H.; Dung, T.; Hien, N.; Nga, P.; Chughtai, A.; Rahman, B.; Dwyer, D.; Wang, Q. A Cluster Randomised Trial of Cloth Masks Compared with Medical Masks in Healthcare Workers. Bmj Open 2015, 5, e006577  DOI: 10.1136/bmjopen-2014-006577
      [Crossref], [PubMed], Google Scholar
      There is no corresponding record for this reference.
    17. 17
      Kulkarni, P.; Baron, P.; Willeke, K. Aerosol Measurement: Principles, Techniques and Applications. 3rd ed.; John Wiley & Sons, Inc.: Hoboken, NJ, 2011; 107– 128.
      [Crossref], Google Scholar
      There is no corresponding record for this reference.
    18. 18
      Brown, R.; Wake, D. Air Filtration by Interception—Theory and Experiment. J. Aerosol Sci. 1991, 22, 181– 186,  DOI: 10.1016/0021-8502(91)90026-E
      [Crossref], [CAS], Google Scholar
      18
      Air filtration by interception - theory and experiment
      Brown, R. C.; Wake, D.
      Journal of Aerosol Science (1991), 22 (2), 181-6CODEN: JALSB7; ISSN:0021-8502.
      A model of aerosol particle capture in filters, by interception, is developed, by using a more general approach than simple single-fiber theory. A simple relationship exists between aerosol penetration and particle size, fiber size, and the quotient of pressure drop and filtration velocity. Agreement between theory and expt. is good, both for the fundamental dependence of penetration on aerosol size and for the abs. values of penetration.
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    19. 19
      Emi, H.; Okuyama, K.; Yoshioka, N. Prediction of Collection Efficiency of Aerosols by High-Porosity Fibrous Filter. J. Chem. Eng. Jpn. 1973, 6, 349– 354,  DOI: 10.1252/jcej.6.349
      [Crossref], [CAS], Google Scholar
      19
      Prediction of collection efficiency of aerosols by a high-porosity fibrous filter
      Emi, Hitoshi; Okuyama, Kikuo; Yoshioka, Naoya
      Journal of Chemical Engineering of Japan (1973), 6 (4), 349-54CODEN: JCEJAQ; ISSN:0021-9592.
      In the filtration of aerosols by a high-porosity fiber mat, the deposition of particles smaller than a few microns in diam. on a fiber depends on the combined effect of initial impaction, Brownian diffusion, gravitational settling, and direct interception, when neither particles nor filters are elec. charged. The overall collection efficiency vs. particle diam. curves show distinct min. Decreasing parts of the efficiency vs. the particle diam. are in the diffusion-predominant region, whereas increasing parts are gravity-predominant in the low-velocity range, which is shifted to inertia with increasing velocity. The overall collection efficiency vs. linear gas velocity curves also show distinct min. Results can be used for designing fibrous filters with porosities >0.98.
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    20. 20
      Stechkina, I.; Fuchs, N. Studies on Fibrous Aerosol Filters-I. Calculation of Diffusional Deposition of Aerosols in Fibrous Filters. Ann. Occup. Hyg. 1966, 9, 59– 64,  DOI: 10.1093/annhyg/9.2.59
      [Crossref], Google Scholar
      There is no corresponding record for this reference.
    21. 21
      Stechkina, I.; Kirsch, A.; Fuchs, N. Studies on Fibrous Aerosol Filters-IV Calculation of Aerosol Deposition in Model Filters In the Range of Maximum Penetration. Ann. Occup. Hyg. 1969, 12, 1– 8,  DOI: 10.1093/annhyg/12.1.1
      [Crossref], [PubMed], [CAS], Google Scholar
      21
      Studies on fibrous aerosol filters. IV. Calculation of aerosol deposition in model filters in the range of maximum penetration
      Stechkina I B; Kirsch A A; Fuchs N A
      The Annals of occupational hygiene (1969), 12 (1), 1-8 ISSN:0003-4878.
      There is no expanded citation for this reference.
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    22. 22
      Lee, K.; Liu, B. Theoretical Study of Aerosol Filtration by Fibrous Filters. Aerosol Sci. Technol. 1982, 1, 147– 161,  DOI: 10.1080/02786828208958584
      [Crossref], Google Scholar
      There is no corresponding record for this reference.
    23. 23
      Podgórski, A.; Bałazy, A.; Gradoń, L. Application of Nanofibers to Improve the Filtration Efficiency of the Most Penetrating Aerosol Particles in Fibrous Filters. Chem. Eng. Sci. 2006, 61, 6804– 6815,  DOI: 10.1016/j.ces.2006.07.022
      [Crossref], [CAS], Google Scholar
      23
      Application of nanofibers to improve the filtration efficiency of the most penetrating aerosol particles in fibrous filters
      Podgorski, Albert; Balazy, Anna; Gradon, Leon
      Chemical Engineering Science (2006), 61 (20), 6804-6815CODEN: CESCAC; ISSN:0009-2509. (Elsevier Ltd.)
      Conventional, mech. fibrous filters made of microfibers exhibit a local min. of fractional collection efficiency in the aerosol particle size-range between 100 and 500 nm, which is called the most penetrating particle size (MPPS). Simple theor. calcns. predict that this efficiency may be significantly increased using nanofibrous media. The main objective of this paper is an exptl. verification of these expectations and simultaneously checking whether this anticipated gain in the filtration efficiency is not overpaid with an excessive pressure drop. For this purpose we developed a modified melt-blown technol., which allowed us to produce filters composed of micrometer as well as nanometer sized fibers. One conventional microfibrous filter and five nanofibrous filters were examd. The complete structural characteristics, pressure drop and efficiency of removal of aerosol particles with diams. 10-500 nm were detd. for all media. The results of the expts. confirmed that using nanofibrous filters a significant growth of filtration efficiency for the MPPS range can be achieved and the pressure drop rises moderately. Simultaneously, we noticed a shift of the MPPS towards smaller particles. Consequently, the quality factor for bilayer systems composed of a microfibrous support and a nanofibrous facial layer was considerably higher than this one for a conventional microfibrous filter alone. Addnl., it was found that utilization of many-layer nanofibrous filters combined with a single microfibrous backing layer is even more profitable from the quality factor standpoint. Comparing exptl. results with theor. calcns. based on the single-fiber theory we concluded that for microfibrous filters a fairly good agreement can be obtained if the resistance-equiv. fiber diam. is used in calcns. instead of the mean count diam. detd. from the SEM images anal.; in the latter case, filtration efficiency computed theor. is slightly overestimated. This is even more evident for nanofibrous media, suggesting that in such case a structural filter inhomogeneity has a strong influence on the filter efficiency and its resistance and one should strive for minimization of this effect manufg. nanofibrous filters as homogeneous as possible. We can finally conclude that fibrous filters contg. nanofibers, which are produced using the melt-blown technique, are very promising and economic tools to enhance filtration of the most penetrating aerosol particles.
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    24. 24
      Specification for HEPA Filters Used by DOE Contractors; DOE-STD-3020–2015; U. S. Department of Energy: Washington, D.C., 2015; pp 1– 29.
      Google Scholar
      There is no corresponding record for this reference.
    25. 25
      Hinds, W. C. Aerosol Technology: Properties, Behavior, and Measurement of Airborne Particles, 2nd ed.; John Wiley & Sons, Inc.: New York, 1999; pp 182– 205.
      Google Scholar
      There is no corresponding record for this reference.
    26. 26
      Rengasamy, S.; Shaffer, R.; Williams, B.; Smit, S. A Comparison of Facemask and Respirator Filtration Test Methods. J. Occup. Environ. Hyg. 2017, 14, 92– 103,  DOI: 10.1080/15459624.2016.1225157
      [Crossref], [PubMed], [CAS], Google Scholar
      26
      A comparison of facemask and respirator filtration test methods
      Rengasamy Samy; Shaffer Ronald; Williams Brandon; Smit Sarah
      Journal of occupational and environmental hygiene (2017), 14 (2), 92-103 ISSN:.
      NIOSH published a Federal Register Notice to explore the possibility of incorporating FDA required filtration tests for surgical masks (SMs) in the 42 CFR Part 84 respirator certification process. There have been no published studies comparing the filtration efficiency test methods used for NIOSH certification of N95 filtering facepiece respirators (N95 FFRs) with those used by the FDA for clearance of SMs. To address this issue, filtration efficiencies of "N95 FFRs" including six N95 FFR models and three surgical N95 FFR models, and three SM models were measured using the NIOSH NaCl aerosol test method, and FDA required particulate filtration efficiency (PFE) and bacterial filtration efficiency (BFE) methods, and viral filtration efficiency (VFE) method. Five samples of each model were tested using each method. Both PFE and BFE tests were done using unneutralized particles as per FDA guidance document. PFE was measured using 0.1 μm size polystyrene latex particles and BFE with ∼3.0 μm size particles containing Staphylococcus aureus bacteria. VFE was obtained using ∼3.0 μm size particles containing phiX 174 as the challenge virus and Escherichia coli as the host. Results showed that the efficiencies measured by the NIOSH NaCl method for "N95 FFRs" were from 98.15-99.68% compared to 99.74-99.99% for PFE, 99.62-99.9% for BFE, and 99.8-99.9% for VFE methods. Efficiencies by the NIOSH NaCl method were significantly (p = <0.05) lower than the other methods. SMs showed lower efficiencies (54.72-88.40%) than "N95 FFRs" measured by the NIOSH NaCl method, while PFE, BFE, and VFE methods produced no significant difference. The above results show that the NIOSH NaCl method is relatively conservative and is able to identify poorly performing filtration devices. The higher efficiencies obtained using PFE, BFE and VFE methods show that adding these supplemental particle penetration methods will not improve respirator certification.
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    27. 27
      Determination of Particulate Filter Efficiency Level for N95 Series Filters Against Solid Particulates for Non-Powdered, Air-Purifying Respirators Standard Testing Procedure (STP); TEB-APR-STP-0059; National Institute for Occupational Safety and Health: Pittsburgh, PA, 2019; pp 1– 9.
      Google Scholar
      There is no corresponding record for this reference.
    28. 28
      Leung, N.; Chu, D.; Shiu, E.; Chan, K.; Mcdevitt, J.; Hau, B.; Yen, H.; Li, Y.; Ip, D.; Peiris, J.; Seto, W.; Leung, G.; Milton, D.; Cowling, B. Respiratory Virus Shedding in Exhaled Breath and Efficacy of Face Masks. Nat. Med. (N. Y., NY, U. S.) 2020, 26, 676– 680,  DOI: 10.1038/s41591-020-0843-2
      [Crossref], [PubMed], [CAS], Google Scholar
      28
      Respiratory virus shedding in exhaled breath and efficacy of face masks
      Leung, Nancy H. L.; Chu, Daniel K. W.; Shiu, Eunice Y. C.; Chan, Kwok-Hung; McDevitt, James J.; Hau, Benien J. P.; Yen, Hui-Ling; Li, Yuguo; Ip, Dennis K. M.; Peiris, J. S. Malik; Seto, Wing-Hong; Leung, Gabriel M.; Milton, Donald K.; Cowling, Benjamin J.
      Nature Medicine (New York, NY, United States) (2020), 26 (5), 676-680CODEN: NAMEFI; ISSN:1078-8956. (Nature Research)
      Abstr.: We identified seasonal human coronaviruses, influenza viruses and rhinoviruses in exhaled breath and coughs of children and adults with acute respiratory illness. Surgical face masks significantly reduced detection of influenza virus RNA in respiratory droplets and coronavirus RNA in aerosols, with a trend toward reduced detection of coronavirus RNA in respiratory droplets. Our results indicate that surgical face masks could prevent transmission of human coronaviruses and influenza viruses from symptomatic individuals.
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    29. 29
      Schiefter, H.; Taft, D.; Porter, J. Effect of Number of Warp and Filling Yarns per Inch and Some Other Elements of Construction on the Properties of Cloth. J. Res. Natl. Bur. Stand. 1936, 16, 139– 147,  DOI: 10.6028/jres.016.004
      [Crossref], Google Scholar
      There is no corresponding record for this reference.
    30. 30
      Mainelis, G.; Willeke, K.; Baron, P.; Grinshpun, S.; Reponen, T. Induction Charging and Electrostatic Classification of Micrometer-Size Particles for Investigating the Electrobiological Properties of Airborne Microorganisms. Aerosol Sci. Technol. 2002, 36, 479– 491,  DOI: 10.1080/027868202753571304
      [Crossref], [CAS], Google Scholar
      30
      Induction charging and electrostatic classification of micrometer-size particles for investigating the electrobiological properties of airborne microorganisms
      Mainelis, Gediminas; Willeke, Klaus; Baron, Paul; Grinshpun, Sergey A.; Reponen, Tiina
      Aerosol Science and Technology (2002), 36 (4), 479-491CODEN: ASTYDQ; ISSN:0278-6826. (Taylor & Francis)
      Our earlier studies have shown that the electrostatic collection technique, a potentially "gentle" bioaerosol collection method, allows for efficient collection of airborne bacteria, but sensitive bacteria such as Pseudomonas fluorescens (P. fluorescens) lose their culturability during collection. We hypothesized that excessive stress was imposed on the sensitive bacteria by the sampler's conventional corona charging mechanism. In this research, we developed and built an exptl. setup that allows us to analyze electrobiol. properties of airborne microorganisms. In this exptl. system, we imparted elec. charges on airborne biol. and nonbiol. particles by aerosolizing them in the presence of an elec. field. The charged P. fluorescens test bacteria and NaCl test particles were then channeled into a parallel plate mobility analyzer, which we have designed so that bacteria and inert particles carrying specific charge ranges can be extd. and made available for further anal. When testing the exptl. system, we related the extd. particle concns. to the total particle concn. and obtained the charge distributions of these particles at different charging conditions. Our results have shown that even without charging, aerosolized P. fluorescens bacteria have a net neg. charge and can carry up to 13,000 elementary charges per bacterium. In contrast, the NaCl particles were found to carry very few elec. charges. We concluded that the elec. charge carried by a bacterium consists of 2 components: its own natural charge, which can be high, and the charge imposed on it by the dispersion process. Our expts. have shown that the charge distributions on biol. and nonbiol. particles can be effectively manipulated by varying the external elec. field during their aerosolization. Since airborne microorganisms may carry high internal elec. charges, their collection by elec. field forces may be possible without first elec. charging them.
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    31. 31
      Willeke, K.; Whitby, K. Atmospheric Aerosols: Size Distribution Interpretation. J. Air Pollut. Control Assoc. 1975, 25, 529– 534,  DOI: 10.1080/00022470.1975.10470110
      [Crossref], Google Scholar
      There is no corresponding record for this reference.
    32. 32
      Chen, C.; Huang, S. The Effects of Particle Charge on the Performance of a Filtering Facepiece. Am. Ind. Hyg. Assoc. J. 1998, 59, 227– 233,  DOI: 10.1080/15428119891010488
      [Crossref], [PubMed], [CAS], Google Scholar
      32
      The effects of particle charge on the performance of a filtering facepiece
      Chen C C; Huang S H
      American Industrial Hygiene Association journal (1998), 59 (4), 227-33 ISSN:0002-8894.
      This study quantitatively determined the effect of electrostatic charge on the performance of an electret filtering facepiece. Monodisperse challenge corn oil aerosols with uniform charges were generated using a modified vibrating orifice monodisperse aerosol generator. The aerosol size distributions and concentrations upstream and downstream of an electret filter were measured using an aerodynamic particle sizer, an Aerosizer, and a scanning mobility particle sizer. The aerosol charge was measured by using an aerosol electrometer. The tested electret filter had a packing density of about 0.08, fiber size of 3 microns, and thickness of 0.75 mm. As expected, the primary filtration mechanisms for the micrometer-sized particles are interception and impaction, especially at high face velocities, while electrostatic attraction and diffusion are the filtration mechanisms for submicrometer-sized aerosol particles. The fiber charge density was estimated to be 1.35 x 10(-5) coulomb per square meter. After treatment with isopropanol, most of fiber charges were removed, causing the 0.3-micron aerosol penetration to increase from 36 to 68%. The air resistance of the filter increased slightly after immersion in the isopropanol, probably due to the coating of impurities in isopropanol. The aerosol penetration decreased with increasing aerosol charge. The most penetrating aerosol size became larger as the aerosol charge increased, e.g., from 0.32 to 1.3 microns when the aerosol charge increased from 0 to 500 elementary charges.
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    33. 33
      Kowalski, W.; Bahnfleth, W.; Whittam, T. Filtration of Airborne Microorganisms: Modeling and Prediction. In AHRAE Transactions, Seattle WA, 06/18/1999–06/23/1999; Geshwiler, M., Harrell, D., Roberson, T., Eds.; American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.: Seattle, WA, 1999; Vol. 4273, pp 4– 17.
      Google Scholar
      There is no corresponding record for this reference.
    34. 34
      Zhou, S.; Lukula, S.; Chiossone, C.; Nims, R.; Suchmann, D.; Ijaz, M. Assessment of a Respiratory Face Mask for Capturing Air Pollutants and Pathogens Including Human Influenza and Rhinoviruses. J. Thorac. Dis. 2018, 10, 2059– 2069,  DOI: 10.21037/jtd.2018.03.103
      [Crossref], [PubMed], [CAS], Google Scholar
      34
      Assessment of a respiratory face mask for capturing air pollutants and pathogens including human influenza and rhinoviruses
      Zhou S Steve; Lukula Salimatu; Chiossone Cory; Suchmann Donna B; Nims Raymond W; Ijaz M Khalid; Ijaz M Khalid
      Journal of thoracic disease (2018), 10 (3), 2059-2069 ISSN:2072-1439.
      BACKGROUND: Prevention of infection with airborne pathogens and exposure to airborne particulates and aerosols (environmental pollutants and allergens) can be facilitated through use of disposable face masks. The effectiveness of such masks for excluding pathogens and pollutants is dependent on the intrinsic ability of the masks to resist penetration by airborne contaminants. This study evaluated the relative contributions of a mask, valve, and Micro Ventilator on aerosol filtration efficiency of a new N95 respiratory face mask. METHODS: The test mask was challenged, using standardized methods, with influenza A and rhinovirus type 14, bacteriophage ΦΧ174, Staphylococcus aureus (S. aureus), and model pollutants. The statistical significance of results obtained for different challenge microbial agents and for different mask configurations (masks with operational or nonoperational ventilation fans and masks with sealed Smart Valves) was assessed. RESULTS: The results demonstrate >99.7% efficiency of each test mask configuration for exclusion of influenza A virus, rhinovirus 14, and S. aureus and >99.3% efficiency for paraffin oil and sodium chloride (surrogates for PM2.5). Statistically significant differences in effectiveness of the different mask configurations were not identified. The efficiencies of the masks for excluding smaller-size (i.e., rhinovirus and bacteriophage ΦΧ174) vs. larger-size microbial agents (influenza virus, S. aureus) were not significantly different. CONCLUSIONS: The masks, with or without features intended for enhancing comfort, provide protection against both small- and large-size pathogens. Importantly, the mask appears to be highly efficient for filtration of pathogens, including influenza and rhinoviruses, as well as the fine particulates (PM2.5) present in aerosols that represent a greater challenge for many types of dental and surgical masks. This renders this individual-use N95 respiratory mask an improvement over the former types of masks for protection against a variety of environmental contaminants including PM2.5 and pathogens such as influenza and rhinoviruses.
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    35. 35
      Lee, S.; Obendorf, S. Statistical Model of Pesticide Penetration through Woven Work Clothing Fabrics. Arch. Environ. Contam. Toxicol. 2005, 49, 266– 273,  DOI: 10.1007/s00244-004-0127-8
      [Crossref], [PubMed], [CAS], Google Scholar
      35
      Statistical Model of Pesticide Penetration Through Woven Work Clothing Fabrics
      Lee, Seungsin; Obendorf, S. Kay
      Archives of Environmental Contamination and Toxicology (2005), 49 (2), 266-273CODEN: AECTCV; ISSN:0090-4341. (Springer Science+Business Media, Inc.)
      Statistical models estg. the level of protection and thermal comfort performance of woven fabrics were developed using simple fabric and liq. parameters. Eighteen woven fabrics were evaluated against three pesticide mixts. of atrazine and pendimethalin at different concns. Using three mixts. that represent a range of both surface tension and viscosity, percentages of pesticide penetration are measured, along with fabric thickness, fabric cover factor, yarn twist factor, yarn packing factor, solid vol. fraction, wicking height, and air permeability. Statistical analyses are performed to examine the relationship between liq./fabric parameters and pesticide penetration. Statistical analyses show that fabric cover factor, yarn twist factor, viscosity of pesticide mixt., crit. surface tension of solid, and wicking height are significant parameters affecting pesticide penetration. For this purpose, cover factor and twist factor are better parameters in describing the geometry of woven fabrics than solid vol. fraction. Modeling of comfort performance of woven fabric based on simple textile parameters shows that the combination of fabric thickness, cover factor, yarn twist factor and yarn packing factor can be used to est. air permeability of woven fabric. These findings could be used for developing selection charts or tools as guidelines for the selection of personal protective equipment for use in hot, humid environments.
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    36. 36
      Zhao, M.; Liao, L.; Xiao, W.; Yu, X.; Wang, H.; Wang, Q.; Lin, Y.; Kilinc-Balci, F.; Price, A.; Chu, L.; Chu, M.; Chu, S.; Cui, Y., Household Materials Selection for Homemade Cloth Face Coverings and Their Filtration Efficiency Enhancement with Triboelectric Charging. Nano Lett. . 2020.  DOI: 10.1021/acs.nanolett.0c02211 .
      [ACS Full Text ACS Full Text], Google Scholar
      There is no corresponding record for this reference.
    37. 37
      Alekseeva, L. Theoretical Aspects of Predicting the Electrostatic Properties of Textile Materials. Fibre Chem. 2007, 39, 225– 226,  DOI: 10.1007/s10692-007-0047-2
      [Crossref], [CAS], Google Scholar
      37
      Theoretical aspects of predicting the electrostatic properties of textile materials
      Alekseeva, L. V.
      Fibre Chemistry (2007), 39 (3), 225-226CODEN: FICYAP; ISSN:0015-0541. (Springer)
      A theor. method was developed for detg. the electrostatic state of different chem. fibers. Math. relations that can be used to det. the elec. capacitance of chem. fibers of different configuration were obtained. The inverse problem was solved - finding the functional dependence of the dielec. const. of the material investigated on the initial capacitance.
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    38. 38
      Žilinskas, P.; Lozovski, T.; Jankauskas, V.; Jurksus, J. Electrostatic Properties and Characterization of Textile Materials Affected by Ion Flux. Mater. Sci.-Polym. 2013, 19, 61– 66,  DOI: 10.5755/j01.ms.19.1.3828
      [Crossref], Google Scholar
      There is no corresponding record for this reference.
    39. 39
      Kadolph, S.; Marcketti, S. Textiles, 12th ed.; Pearson: Boston, MA, 2016; pp 164– 165.
      Google Scholar
      There is no corresponding record for this reference.
    40. 40
      Radney, J.; Zangmeister, C. Comparing Aerosol Refractive Indices Retrieved from Full Distribution and Size- and Mass-Selected Measurements. J. Quant. Spectrosc. Radiat. Transfer 2018, 220, 52– 66,  DOI: 10.1016/j.jqsrt.2018.08.021
      [Crossref], [CAS], Google Scholar
      40
      Comparing aerosol refractive indices retrieved from full distribution and size- and mass-selected measurements
      Radney, James G.; Zangmeister, Christopher D.
      Journal of Quantitative Spectroscopy & Radiative Transfer (2018), 220 (), 52-66CODEN: JQSRAE; ISSN:0022-4073. (Elsevier Ltd.)
      Refractive index retrievals (also termed inverse Mie methods or optical closure) have seen considerable use as a method to ext. the refractive index of aerosol particles from measured optical properties. Retrievals of an aerosol refractive index use one of two primary methods: 1) measurements of the extinction, absorption and/or scattering cross-sections or efficiencies of size- (and mass-) selected particles for mass-mobility refractive index retrievals (MM-RIR) or 2) measurements of aerosol size distributions and a combination of the extinction, absorption and/or scattering coeffs. for full distribution refractive index retrievals (FD-RIR). These two methods were compared in this study using pure and mixts. of ammonium sulfate (AS) and nigrosin aerosol, which constitute a non-absorbing and absorbing material, resp. The results indicate that the retrieved complex refractive index values are correlated to the amt. of nigrosin in the aerosol but can be highly variable with differences in the real and imaginary components that range between -0.002 and 0.216 and -0.013 and 0.086; the av. and std. deviation of the differences are 0.046 ± 0.046 and 0.023 ± 0.033, resp. Forward calcn. of the optical properties yielded av. abs. values of the relative deviation of ≈ 15% and ≈ 26% for FD-RIR data using the MM-RIR values and contrariwise. The range of retrieved refractive indexes were used to calc. the normalized global av. aerosol radiative forcing of a model accumulation mode remote continental aerosol. Deviations using the refractive indexes of the pure materials range from 9% to 32% for AS and 27% to 45% for nigrosin. For mixts. of nigrosin and AS, deviations were all > 100% and not always able to capture the correct direction of the forcing; i.e., pos. vs. neg.
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    41. 41
      Wiedensohler, A. An Approximation of the Bipolar Charge Distribution for Particles in the Submicron Size Range. J. Aerosol Sci. 1988, 19, 387– 389,  DOI: 10.1016/0021-8502(88)90278-9
      [Crossref], [CAS], Google Scholar
      41
      An approximation of the bipolar charge distribution for particles in the submicron size range
      Wiedensohler, A.
      Journal of Aerosol Science (1988), 19 (3), 387-9CODEN: JALSB7; ISSN:0021-8502.
      An empirical equation is proposed which permits rapid calcn. of the bipolar charge distribution for the aerosol size range 1-1000 nm. This equation approximates the distribution calcd. from the N. Fuchs (1963) model.
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    42. 42
      Radney, J.; Ma, X.; Gillis, K.; Zachariah, M.; Hodges, J.; Zangmeister, C. Direct Measurements of Mass-Specific Optical Cross Sections of Single Component Aerosol Mixtures. Anal. Chem. 2013, 85, 8319– 8325,  DOI: 10.1021/ac401645y
      [ACS Full Text ACS Full Text], [CAS], Google Scholar
      42
      Direct Measurements of Mass-Specific Optical Cross Sections of Single-Component Aerosol Mixtures
      Radney, James G.; Ma, Xiaofei; Gillis, Keith A.; Zachariah, Michael R.; Hodges, Joseph T.; Zangmeister, Christopher D.
      Analytical Chemistry (Washington, DC, United States) (2013), 85 (17), 8319-8325CODEN: ANCHAM; ISSN:0003-2700. (American Chemical Society)
      Optical properties of atm. aerosols vary widely, depending on particle compn., morphol., and mixing state. This aerosol diversity and complexity motivates measurement techniques which can discriminate and quantify a variety of single- and multi-component aerosols that are internally and externally mixed. This work presents a new combination of techniques to directly measure mass-specific extinction and absorption cross sections of lab.-generated aerosols relevant to atm. studies. The approach used tandem differential mobility and aerosol particle mass analyzers, cavity ring-down and photoacoustic spectrometers, and a condensation particle counter. This suite of instruments enabled aerosol particle size; mass, extinction, and absorption coeffs.; and aerosol no. d. measurements, resp. Together, these observables yield mass-specific extinction and absorption cross sections without any model particle morphol. or accounting for sample collection artifacts. This was demonstrated in a set of case studies involving complete aerosol sepn. by charge, external mixt. sepn. by mass, and discrimination between particle types by effective d. and single-scattering albedo.
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    43. 43
      Radney, J.; Zangmeister, C. Practical Limitations of Aerosol Separation by a Tandem Differential Mobility Analyzer–Aerosol Particle Mass Analyzer. Aerosol Sci. Technol. 2016, 50, 160– 172,  DOI: 10.1080/02786826.2015.1136733
      [Crossref], [PubMed], [CAS], Google Scholar
      43
      Practical limitations of aerosol separation by a tandem differential mobility analyzer-aerosol particle mass analyzer
      Radney, James G.; Zangmeister, Christopher D.
      Aerosol Science and Technology (2016), 50 (2), 160-172CODEN: ASTYDQ; ISSN:0278-6826. (Taylor & Francis, Inc.)
      A cavity ring-down spectrometer and condensation particle counter were used to investigate the limitations in the sepn. of singly and multiply charged aerosol particles by a tandem differential mobility analyzer (DMA) and aerosol particle mass analyzer (APM). The impact of particle polydispersity and morphol. was investigated using three materials: nearly monodisperse polystyrene latex nanospheres (PSL); polydisperse, nearly spherical ammonium sulfate (AS), and polydisperse lacey fractal soot agglomerates. PSL and AS particles were easily resolved as a function of charge. For soot, the presence of multiply charged particles severely affects the isolation of the singly charged particles. In cases where the DMA-APM was unable to fully resolve the singly charged particles of interest, the peak mass deviated by up to 13% leading to errors in the mass specific extinction cross section of over 100%. For measurements of nonspherical particles, nonsym. distributions of concn. as a function of mass were a sign of the presence of multiply charged particles. Under these conditions, the effects of multiply charged particles can be reduced by using a second charge neutralizer after the DMA and prior to the APM. Diln. of the aerosol stream serves to decrease the total no. concn. of particles and does not remove the contributions of multiply charged particles.
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    44. 44
      Buys, T.; De Clerk, K. Bi-Gaussian Fitting of Skewed Peaks. Anal. Chem. 1972, 44, 1273– 1275,  DOI: 10.1021/ac60315a005
      [ACS Full Text ACS Full Text], [CAS], Google Scholar
      44
      Bi-Gaussian fitting of skewed peaks
      Buys, T. S.; De Clerk, K.
      Analytical Chemistry (1972), 44 (7), 1273-5CODEN: ANCHAM; ISSN:0003-2700.
      The bi-Gaussian fitting function can be used for predicting the zeroth and 1st statistical moments (related to the mass and the thermodynamics of the system, resp.) of asym. chromatogram peaks. The fitting of a Poisson distribution at the peak max. and at half-height with a bi-Gaussian distribution showed that the 2nd and 3rd moments (related to peak width and asymmetry, resp.) of skewed peaks cannot be predicted. The bi-Gaussian function can serve as the basis for a more refined computer anal. of overlapping peaks, and can be used for the empirical prediction of retention times.
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    45. 45
      Determination of Inhalation Resistance TEB-APR-STP-0007; National Institute for Occupational Safety and Health: Pittsburgh, PA, 2019; pp 1– 7.
      Google Scholar
      There is no corresponding record for this reference.
    46. 46
      Determination of Exhalation Resistance TEB-APR-STP-0003; National Institute for Occupational Safety and Health: Pittsburgh, PA, 2019; pp 1– 6.
      Google Scholar
      There is no corresponding record for this reference.
    47. 47
      Chen, C.; Willeke, K. Aerosol Penetration through Surgical Masks. Am. J. Infect. Control 1992, 20, 177– 184,  DOI: 10.1016/S0196-6553(05)80143-9
      [Crossref], [PubMed], [CAS], Google Scholar
      47
      Aerosol penetration through surgical masks
      Chen C C; Willeke K
      American journal of infection control (1992), 20 (4), 177-84 ISSN:0196-6553.
      BACKGROUND: Surgical masks are used in hospitals to reduce postoperative infection in patients. The presence of aerosols containing pathogens makes it desirable to protect the medical staff as well. METHODS: The collection efficiencies of surgical masks measured with two aerosol-size spectrometers. The flow rates through the masks were varied from 5 to 100 L/min to study the flow dependency. For comparison, several industrial-type respirators were also tested. RESULTS: A surgical mask consisting of filter material performed better than did a surgical mask consisting only of a shell with a coarse pore structure. The latter passed 80% of submicrometer-sized aerosols with little flow dependency, whereas the penetration of submicrometer-sized aerosols through the mask made of filter material ranged from 25% at a flow rate of 5 L/min to 70% at 100 L/min. CONCLUSIONS: The mask that has the highest collection efficiency is not necessarily the best mask from the perspective of the filter-quality factor, which considers not only the capture efficiency but also the air resistance. Although surgical mask media may be adequate to remove bacteria exhaled or expelled by health care workers, they may not be sufficient to remove the submicrometer-size aerosols containing pathogens to which these health care workers are potentially exposed.
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    48. 48
      Food and Drugs; Sterilization Wrap, 21CFR880.6850; Food and Drug Administration: Silver Spring, MD, 2020.
      Google Scholar
      There is no corresponding record for this reference.
    49. 49
      Chattopadhyay, S.; Hatton, T.; Rutledge, G. Aerosol Filtration Using Electrospun Cellulose Acetate Fibers. J. Mater. Sci. 2016, 51, 204– 217,  DOI: 10.1007/s10853-015-9286-4
      [Crossref], [CAS], Google Scholar
      49
      Aerosol filtration using electrospun cellulose acetate fibers
      Chattopadhyay, Saptarshi; Hatton, T. Alan; Rutledge, Gregory C.
      Journal of Materials Science (2016), 51 (1), 204-217CODEN: JMTSAS; ISSN:0022-2461. (Springer)
      Aerosol filtration using electrospun cellulose acetate filters with different mean fiber diams. is discussed, and results are compared with those for 2 conventional filter media: glass fiber filter and cellulose acetate microfiber filter. Filter performance was assessed using 2 aerosols, 1 solid (NaCl) and 1 liq. (di-Et hexyl sebacate), under relatively high face velocity (45 cm/s) conditions. Exptl. observations were compared to theor. predictions based on single fiber filtration efficiency. Results indicated mechanisms for single fiber filtration efficiency provide reasonable predictions of the most penetrating particle size (40-270 nm), percentage penetration (0.03-70%), and fiber diam. (0.1-24 μm). Using an anal. based on blocking filtration laws, the authors concluded filtration by cake formation dominated for NaCl aerosols on electrospun filter media; filters with larger fiber diam. exhibited a transition in mechanisms, from an initial regime characterized by pore-blocking to a later regime characterized by cake formation. The liq. aerosol did not exhibit cake formation, even for the smallest fiber diams., and had much a smaller effect on pressure drop than solid aerosols. Electrospun filters demonstrated slightly better quality factors vs. the com. glass fiber filter, at a much lower thickness. Generally, results demonstrated control of the electrospun cellulose acetate fiber properties for air filtration applications.
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    50. 50
      Payen, J.; Vroman, P.; Lewandowski, M.; Perwuelz, A.; Callé-Chazelet, S.; Thomas, D. Influence of Fiber Diameter, Fiber Combinations and Solid Volume Fraction on Air Filtration Properties in Nonwovens. Text. Res. J. 2012, 82, 1948– 1959,  DOI: 10.1177/0040517512449066
      [Crossref], [CAS], Google Scholar
      50
      Influence of fiber diameter, fiber combinations and solid volume fraction on air filtration properties in nonwovens
      Payen, Julien; Vroman, Philippe; Lewandowski, Maryline; Perwuelz, Anne; Calle-Chazelet, Sandrine; Thomas, Dominique
      Textile Research Journal (2012), 82 (19), 1948-1959, 12 pp.CODEN: TRJOA9; ISSN:0040-5175. (Sage Publications Ltd.)
      In air filtration, nonwoven materials are known to be pertinent structures for fine filtration and moderate pressure drop. In order to develop a filter that combines good permeability and high efficiency, it is important to identify the relevant structural parameters of the nonwoven. The main criteria studied in this paper are fiber fineness, solid vol. fraction and basis length (total length of fiber in unit area of nonwoven). The effect of combining different fiber diams. in order to reach the best compromise is also investigated. Our results show that the use of binary blends of different fiber diams. improves overall filtration behavior, in comparison to nonwoven filters with equiv. unimodal diam. distribution. A theor. filtration model is used to predict filtration behavior for different structural characteristics and these predictions are compared to exptl. results. However, this comparison demonstrates the limits of existing models in the case of fiber blends.
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    51. 51
      Hosseini, S.; Tafreshi, H. On the Importance of Fibers’ Cross-Sectional Shape for Air Filters Operating in the Slip Flow Regime. Powder Technol. 2011, 212, 425– 431,  DOI: 10.1016/j.powtec.2011.06.025
      [Crossref], [CAS], Google Scholar
      51
      On the importance of fibers' cross-sectional shape for air filters operating in the slip flow regime
      Hosseini, S. A.; Tafreshi, H. Vahedi
      Powder Technology (2011), 212 (3), 425-431CODEN: POTEBX; ISSN:0032-5910. (Elsevier B.V.)
      In this paper, the effects are studied of fibers cross-sectional shape on the performance of a fibrous filter in the slip and no-slip flow regimes. The slip flow regime is expected to prevail when fiber diam. is comparable in size to the mean free path of the gas mols. (about 65 nm at normal temps. and pressures), whereas the no-slip flow regime describes the aerodynamic condition of flow through media with large fibers. The numerical simulations conducted for flow around single fibers with different geometries indicate that, while the collection efficiency is only weakly affected by the cross-sectional shape of nanofibers, the fiber drag (i.e., permeability of the media) can be considerably influenced by the fiber's shape. Simulating the flow field around nano- and microfibers with circular, square, trilobal, and elliptical cross-sections, it was found that the more streamlined the fiber geometry, the lower the fiber drag caused by a nanofiber relative to that generated by its micron-sized counterpart.
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    52. 52
      Bradow, J.; Davidonis, G. Quantitation of Fiber Quality and the Cotton Production-Processing Interface: A Physiologist’s Perspective. J. Cotton Sci. 2000, 4, 34– 64
      Google Scholar
      There is no corresponding record for this reference.
    53. 53
      Bailey, B. Diameter Relationships of Wool Fibers from Five Breeds of Sheep Raised in South Dakota. J. Agric. Res. 1940, 60, 415– 426
      Google Scholar
      There is no corresponding record for this reference.
    54. 54
      Stobart, R.; Russell, W.; Larsen, S.; Johnson, C.; Kinnison, J. Sources of Variation in Wool Fiber Diameter. J. Anim. Sci. 1986, 62, 1181– 1186,  DOI: 10.2527/jas1986.6251181x
      [Crossref], Google Scholar
      There is no corresponding record for this reference.
    55. 55
      American Sheep Industry Association. Sheep Production Handbook; Sheep Industry Development Program, 1988; wool-13– wool-73.
      Google Scholar
      There is no corresponding record for this reference.
    56. 56
      Grafe, T.; Graham, K. Polymeric Nanofibers and Nanofiber Webs: A New Class of Nonwovens. Int. Nonwovens J. 2003, os-12, 51– 55,  DOI: 10.1177/1558925003os-1200113
      [Crossref], Google Scholar
      There is no corresponding record for this reference.
    57. 57
      Brown, P.; Cox, C. Fibrous Filter Media; Elsevier: Cambridge, MA, 2017; pp 51– 94.
      Google Scholar
      There is no corresponding record for this reference.
    58. 58
      Perumalraj, R. Characterization of Electrostatic Discharge Properties of Woven Fabrics. J. Text. Sci. Eng. 2015, 6, 1– 6,  DOI: 10.4172/2165-8064.1000235
      [Crossref], Google Scholar
      There is no corresponding record for this reference.
    59. 59
      Forsyth, B.; Liu, B.; Romay, F. Particle Charge Distribution Measurement for Commonly Generated Laboratory Aerosols. Aerosol Sci. Technol. 1998, 28, 489– 501,  DOI: 10.1080/02786829808965540
      [Crossref], [CAS], Google Scholar
      59
      Particle charge distribution measurement for commonly generated laboratory aerosols
      Forsyth, Bruce; Liu, Benjamin Y. H.; Romay, Francisco J.
      Aerosol Science and Technology (1998), 28 (6), 489-501CODEN: ASTYDQ; ISSN:0278-6826. (Elsevier Science Inc.)
      An improved particle charge analyzer system has been developed to measure the abs. charge distribution of common generated lab. aerosols. The charge analyzer system consists of an integral cylindrical mobility analyzer used in conjunction with an optical aerosol spectrometer, with computer assisted operation and data redn. The charge analyzer collects aerosol particles over an abs. elec. mobility range from 4.2*10-4 to 400 cm2/(stat · Volt second) and flow rates that can vary from 0.3 to 30 L per min. The charge analyzer has been used to investigate the nature of spray and contact electrification during aerosol generation by measuring the residual charge distribution on the liq. and solid generated particles. In addn., the neutralization of charged particles by bipolar ions also was studied using conventional neutralizers that use ionizing radiation from alpha and beta sources. Charge distribution measurements were performed on alumina dust (Al), Arizona road dust (ARD), potassium chloride (KCl), sodium chloride (NaCl) and di-octyl sebacate (DOS) liq. particles. Aerosol generation devices include a Collison atomizer, a condensation aerosol generator and a fluidized bed dust generator. Our work provides exptl. charge distribution data for comparison with simple models of electrification theory. Exptl. results showed that charge levels of atomized KCl and NaCl particles were high and decreased as the dissolved ion concn. increased. DOS particles generated by evapn.-condensation were both neutral and moderately charged. These conclusions support the existence of a dipole layer at the liq.-gas interface that interacts with dissolved particles and changes their charge state. Alumina and ARD generated by the fluidized bed disperser are highly charged due to strong contact electrification during dispersion. In most cases, the charge on generated aerosols could be reduced to Boltzmann charge equil. conditions by commonly used radioactive neutralizers.
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    60. 60
      Pusic, T.; Grancaric, A.; Soljacic, I.; Ribitsch, V. The Effect of Mercerisation on the Electrokinetic Potential of Cotton. Color. Technol. 1999, 115, 121– 124,  DOI: 10.1111/j.1478-4408.1999.tb00308.x
      [Crossref], Google Scholar
      There is no corresponding record for this reference.
    61. 61
      Schindelin, J.; Arganda-Carreras, I.; Frise, E.; Kaynig, V.; Longair, M.; Pietzsch, T.; Preibisch, S.; Rueden, C.; Saalfeld, S.; Schmid, B.; Tinevez, J.; White, D.; Hartenstein, V.; Eliceiri, K.; Tomancak, P.; Cardona, A. Fiji: An Open-Source Platform for Biological-Image Analysis. Nat. Methods 2012, 9, 676– 682,  DOI: 10.1038/nmeth.2019
      [Crossref], [PubMed], [CAS], Google Scholar
      61
      Fiji: an open-source platform for biological-image analysis
      Schindelin, Johannes; Arganda-Carreras, Ignacio; Frise, Erwin; Kaynig, Verena; Longair, Mark; Pietzsch, Tobias; Preibisch, Stephan; Rueden, Curtis; Saalfeld, Stephan; Schmid, Benjamin; Tinevez, Jean-Yves; White, Daniel James; Hartenstein, Volker; Eliceiri, Kevin; Tomancak, Pavel; Cardona, Albert
      Nature Methods (2012), 9 (7_part1), 676-682CODEN: NMAEA3; ISSN:1548-7091. (Nature Publishing Group)
      Fiji is a distribution of the popular open-source software ImageJ focused on biol.-image anal. Fiji uses modern software engineering practices to combine powerful software libraries with a broad range of scripting languages to enable rapid prototyping of image-processing algorithms. Fiji facilitates the transformation of new algorithms into ImageJ plugins that can be shared with end users through an integrated update system. We propose Fiji as a platform for productive collaboration between computer science and biol. research communities.
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      https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhtVKnurbJ&md5=ad150521a33367d37a800bee853dd9db
    62. 62
      Rueden, C.; Schindelin, J.; Hiner, M.; Dezonia, B.; Walter, A.; Arena, E.; Eliceiri, K. ImageJ2: ImageJ for the Next Generation of Scientific Image Data. BMC Bioinf. 2017, 18, 1– 26,  DOI: 10.1186/s12859-017-1934-z
      [Crossref], [PubMed], Google Scholar
      There is no corresponding record for this reference.
    63. 63
      Thompson, A.; Taylor, B. Guide for the Use of the International System of Units (SI) 811; National Institute of Standards and Technology: Gaithersburg, MD, 2008; p 90.
      [Crossref], Google Scholar
      There is no corresponding record for this reference.
    64. 64
      Shapiro, S.; Wilk, M. An Analysis of Variance Test for Normality (Complete Samples). Biometrika 1965, 52, 591– 611,  DOI: 10.2307/2333709
      [Crossref], Google Scholar
      There is no corresponding record for this reference.
    65. 65
      Bertrand, C. Graphing Wizardry. Science 2000, 289, 1893– 1894,  DOI: 10.1126/science.289.5486.1894
      [Crossref], Google Scholar
      There is no corresponding record for this reference.

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    • FE measurement description and schematic, measurements of particle counts for NU and ND and FE as function of Dm, description of method of image analysis, microscopic images, yarn widths, number of yarns in weft and warp directions, number of yarns cm–2 for each measured sample (PDF)


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