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Energy and Climate

Gas and Propane Combustion from Stoves Emits Benzene and Increases Indoor Air Pollution
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Environmental Science & Technology

Cite this: Environ. Sci. Technol. 2023, 57, 26, 9653–9663
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https://doi.org/10.1021/acs.est.2c09289
Published June 15, 2023

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Abstract

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Exposure pathways to the carcinogen benzene are well-established from tobacco smoke, oil and gas development, refining, gasoline pumping, and gasoline and diesel combustion. Combustion has also been linked to the formation of nitrogen dioxide, carbon monoxide, and formaldehyde indoors from gas stoves. To our knowledge, however, no research has quantified the formation of benzene indoors from gas combustion by stoves. Across 87 homes in California and Colorado, natural gas and propane combustion emitted detectable and repeatable levels of benzene that in some homes raised indoor benzene concentrations above well-established health benchmarks. Mean benzene emissions from gas and propane burners on high and ovens set to 350 °F ranged from 2.8 to 6.5 μg min–1, 10 to 25 times higher than emissions from electric coil and radiant alternatives; neither induction stoves nor the food being cooked emitted detectable benzene. Benzene produced by gas and propane stoves also migrated throughout homes, in some cases elevating bedroom benzene concentrations above chronic health benchmarks for hours after the stove was turned off. Combustion of gas and propane from stoves may be a substantial benzene exposure pathway and can reduce indoor air quality.

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Synopsis

Gas and propane combustion in stoves and ovens releases benzene that migrates throughout the home, sometimes elevating concentrations above health benchmarks.

Introduction

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Natural gas appliances, including furnaces, water heaters, and stoves, emit carbon dioxide through combustion and also emit methane directly into air through leaks and incomplete combustion. (15−17) Methane (CH4), the principal component of natural gas, is the second largest greenhouse gas contributor to global climate change after carbon dioxide. (14) Gas appliances in homes further release health-damaging air pollutants, though only stoves typically release these pollutants directly into home air rather than venting them outdoors as furnaces and water heaters do.
Through combustion, gas stoves also emit toxic chemicals, including carbon monoxide (CO), which inhibits cellular respiration; formaldehyde (HCHO), a carcinogen; and nitrogen dioxide (NO2), a respiratory irritant linked to asthma. (2−6) Under common-use conditions, indoor NO2 from gas stoves can quickly exceed US Environmental Protection Agency (EPA) and World Health Organization (WHO) 1-h exposure benchmarks in kitchen air. (2,4,18,19) NOx (defined here as NO + NO2) pollution has been shown to harm human health; for instance, a meta-analysis of 41 studies on gas stoves and childhood respiratory health concluded that children who live in homes with gas stoves had a 24% higher risk of lifetime asthma and a 42% increased risk of having asthma currently. (20) Furthermore, a recent population-level analysis concluded that approximately 12% of childhood asthma in the U.S. is attributable to gas stoves. (21) More than 1/3 of U.S. households (47 million households) cook with gas, (11) and millions more do so worldwide. (12,13)
Although the formation of NOx, carbon monoxide, and formaldehyde from gas combustion in stoves is relatively well-characterized, other hazardous air pollutants known to form in gas flames, such as benzene, have yet to be quantified indoors associated with gas combustion in stoves. Like carbon monoxide, benzene (C6H6) is a product of incomplete combustion. Benzene is defined as a Group 1 known human carcinogen by the International Agency for Research on Cancer (22) and as a carcinogen by the US EPA. (23) Benzene formation in methane flames is well-characterized in the laboratory, (24−27) and benzene has been observed to form from natural gas combustion in other settings such as during flaring (28) and in utility-scale boilers. (29) Other cooking fuels such as wood, charcoal, kerosene, and liquefied petroleum gas have also been shown to degrade indoor air quality in some cases by emitting pollutants such as benzene. (30) We hypothesized that gas and propane stoves could similarly produce benzene indoors, creating a potential human health risk.
Benzene exposure causes both cancer and noncancerous health effects. Shorter-term benzene exposure suppresses blood cell production, and chronic benzene exposure increases the risk of leukemias and lymphomas. (31,32) The carcinogenic effects of benzene exposure follow a linear dose-response curve with no lower threshold, meaning that any additional benzene exposure increases leukemia and lymphoma risk. (32) In contrast, some adverse noncarcinogenic effects, such as the suppression of blood cell production, likely occur only when benzene exposure exceeds a threshold. (32)
The carcinogenic and noncarcinogenic effects of benzene are reflected in current benzene exposure benchmarks. These benchmarks generally fall between 2.0 μg/m3 (∼0.63 ppbv), established in France, and 5.0 μg/m3 (∼1.6 ppbv), the most common global benchmark adopted by the European Union, India, South Korea, and other jurisdictions. (9) The World Health Organization, however, concluded that for cancer effects, “there is no known exposure threshold for the risks of benzene exposure” and that “it is expedient to reduce indoor exposure levels to as low as possible”. (22) Some jurisdictions have also set indoor exposure benchmarks associated with different time horizons based solely on benzene’s noncarcinogenic risk. For example, the California Office of Environmental Health Hazard Assessment (OEHHA) under the California Environmental Protection Agency (CalEPA) established an 8-h reference exposure level of 3 μg/m3 (∼1 ppbv) in 2014, equal to the state’s chronic exposure level. (8)
Previous research on indoor benzene exposure concluded that various factors in homes can elevate benzene concentrations, particularly tobacco smoke, fossil-fueled appliances such as kerosene stoves, attached garages, and proximity to roads with gasoline-vehicle traffic. (1,10,33−37) Two studies found that benzene concentrations were elevated above the baseline when a gas or propane cooking unit was on but did not quantify benzene emission rates. (36,37)
To our knowledge, ours is the first study to quantify combustion-based benzene emission factors from gas and propane stoves. We also measured benzene emissions from alternative stove types (electric coil, radiant, and induction). To isolate benzene emissions from fuel use from any emissions from cooking food, we quantified benzene emissions from all cooktop elements by boiling water using the same pot in all homes and by measuring emissions in empty ovens. Beyond the fuel, another potential source of benzene associated with cooking is the food, particularly emissions from heating fats and oils. Maximum recommended frying temperatures are approx. 190 °C, (38) and previous research suggested that common frying oils produce not more than 2.5 ng benzene per g oil per minute at 200 °C. (39) We tested whether food itself is a source of benzene by cooking two meal types using nonbenzene-emitting induction cooktops.

Materials and Methods

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Definitions

We define a “cooktop” as a flat surface with 2–6 individual cooking elements, “burners” as cooking elements using a gas or propane flame, “coils” as those with an exposed metal coil that is heated via electric resistance, “radiant hobs” as elements with a metal coil covered by a smooth ceramic or glass surface, and “induction hobs” as elements that heat cookware directly using electromagnetic induction. We therefore define a “cooktop element” broadly as a single burner, coil, or hob.
For ovens, we define gas, propane, and electric ovens as enclosed spaces heated by gas, propane, and electric resistance, respectively (there is currently no oven equivalent of an induction hob). We define a “stove” (also called a “range”) as a freestanding unit that contains both a cooktop and an oven. Stoves typically use the same fuel for the cooktop and oven, although some have a gas cooktop and an electric oven. We grouped electric coils and radiant hobs together in our sampling because they both transfer heat to a pot via conduction. Throughout the paper, we use the term “concentration” for its accessibility in place of the more strictly correct term “molar mixing ratios.” We assume a temperature of 25 °C and a pressure of 1 atm when converting between true concentrations and molar mixing ratios, which yields the conversion 1 ppbv benzene = 3.19 μg benzene m–3.
To promote real-world comparisons (using vocabulary that home cooks use), we refer to burners set to “high” and “low” in homes. Although these categories are qualitative, the least powerful gas burner that we tested on high operated at >1 kW of power (3.4 kBTU h–1), whereas the most powerful gas burner that we tested on low operated at <1 kW (Figure S11). For gas stoves, we therefore define burners on “high” as >1 kW and “low” as <1 kW. In contrast, propane stoves had some overlap in power output across stoves between “high” and “low” settings. Grouping benzene emission results from propane stoves by power output (>1 kW and <1 kW) rather than by “high” and “low” on the burner dials yields similar results to our “high” and “low” groupings (Figure S12). Because electric coils and induction stoves do not emit CO2, we used the qualitative values of “high” and “low” from the stoves to describe their outputs.
As described below, when quantifying benzene emission factors (rates of benzene emitted per unit time), we closed kitchen doors and windows and sometimes sealed parts of the kitchen with plastic to limit the kitchen volume in order to measure the emission rates more accurately (see Figure S8). Throughout the paper, we refer to kitchens partitioned with any plastic as “sealed” kitchens and to kitchens with doors and windows closed but with no plastic sealing as “unsealed” kitchens. When we conducted our long 8-h time course measurements of concentrations in kitchens and bedrooms, we opened interior doors. We refer to these as “open kitchens”.

Measurement Instrumentation

We measured benzene using an Entanglement Technologies, Inc. AROMA VOC analyzer (model ARVOC-191E, RSO), a cavity ring-down analyzer that quantifies benzene concentrations based on the molecule’s infrared spectroscopic absorbance signature. (40) The AROMA analyzer collects one data point every 855 s (14.25 min) and collects sample air for 5 min of each measurement cycle. Thus, each AROMA data point represents a concentration average over 5 min taken once every 15 or so minutes.
To normalize benzene emissions by the amount of gas burned and to calculate the room volume through an ethane injection of known volume, we measured carbon dioxide and ethane using a Picarro cavity ring-down spectrometer (model G-2210i). To confirm results from the Picarro, during portions of our sampling campaign, we also measured ethane using a duplicate Aeris methane/ethane MIRA Ultra Mobile LDS analyzer and CO2 using an Aeris carbon dioxide/nitrous oxide MIRA Ultra Mobile LDS analyzer. We measured carbon monoxide (CO) using a U_MCEA Los Gatos Research analyzer. The calibration of the AROMA VOC analyzer was regularly checked (typically once at the beginning of each sampling day). The calibrations of the other analyzers were checked regularly (typically weekly) and after being transported.

Site Selection

We sampled 87 stoves in 14 counties in California and Colorado between January and December 2022 (see Figure S6 for a map of sampling locations). Our set of sample residences included a range of kitchen sizes in private homes, apartments, and several Airbnb rentals, where we could measure longer─including overnight─time courses (see Figure S7). We selected homes through an online participant sign-up page and neighborhood and community associations (see Table S2 for a summary of the characteristics of stoves that we sampled).

Emission Rate Calculations from Combustion

We calculated benzene emission rates attributable to gas combustion by measuring the increase in benzene concentration through time in sealed and unsealed kitchens (see above), an approach analogous to that used by Lebel et al. to measure methane and NOx emissions from stoves. (2) We converted measured concentrations into emission rates using eq 1:
fb=Vk1nΣi=0nλ(Cb,ti−Cb,ti−1e−λ(ti−ti−1)1−e−λ(ti−ti−1)−Cb,b)
(1)
where fb is the mean benzene emission rate over the course of a measurement (in volume per time), Vk is the kitchen volume, λ is the kitchen chamber’s air exchange constant (in reciprocal time), n is the number of benzene concentration data points collected in a given measurement, Cb, t is the benzene concentration at time t (in parts per billion volume), ti is the timestamp of the ith data point, and Cb, b is the background benzene concentration outside the kitchen chamber (in parts per billion volume; see Supplementary Methods for the derivation of eq 1). We assume that Cb, b is equal to the benzene concentration that we measured inside the kitchen immediately after airing it out with fresh outdoor air. We converted volumetric emission rates into gravimetric emission rates using the temperature measured in the kitchen.
For a perfectly sealed kitchen with λ = 0, note that
limλ→0⁡Vk1nΣi=0nλ(Cb,ti−Cb,ti−1e−λ(ti−ti−1)1−e−λ(ti−ti−1)−Cb,b)=Vk1nΣi=0n(Cb,ti−Cb,ti−1ti−ti−1)
which is the average rate of the benzene concentration rise multiplied by the kitchen volume. We measured the energy output from gas burners and ovens using the flow rate of CO2 and the enthalpy of combustion of methane to calculate the joules (J) of energy emitted per unit time.
We calculated the kitchen volume (Vk) and air exchange constant (λ) using 500 mL injections of ethane as a tracer, using fans to mix the kitchen air. The estimated kitchen volume is the injected ethane volume divided by the peak ethane concentration immediately following injection, and the air exchange constant is the ethane’s decay constant through time after the peak (see Supplementary Methods). We also measured the volume of four kitchens using a laser distance measurer and obtained good agreement with the ethane injection method (slope = 1.1, standard error of the slope = 0.12, r2 = 0.97, and p value of the line fit: 0.01).

Measurement Setup

To sample air in the kitchen or other rooms of interest, we connected polytetrafluoroethane (PTFE) tubing to a stand approximately 1.5 m off the ground, typically in the center of the kitchen or other rooms (and not immediately next to the stove, see Figure S8). We drew air from the kitchen to the analyzers located outside the kitchen using a 7 L min–1 pump.
To measure some benzene emission rates (but never benzene concentrations), we created enclosed kitchen partitions with well-mixed air by closing the kitchen’s doors and windows, closing off some open spaces with plastic in some houses, and placing one or two fans in each kitchen to mix the air while being careful not to disturb the burner flame (see Figure S8). In other cases, we measured benzene emission rates in unsealed kitchens with doors closed but without plastic partitions (see above). We accounted for gaps under doors, in windowpanes, and around any plastic sealing with the measured air exchange constant λ (see above). We used plastic sealing for measuring benzene emission factors only; we never used plastic when reporting benzene concentrations in any rooms. We verified that the plastic we used did not emit detectable benzene by placing approximately 10-fold the amount of plastic used to seal a large kitchen in a closed kitchen at 95 °F and measuring the benzene concentration over 45 min, our typical measurement time. This quantity of plastic did not emit detectable amounts of benzene.
We aimed to eliminate all potential sources and sinks of benzene in the kitchen chamber other than the stove itself. We kept the range hood (a potential sink) off if one was present except when testing hood-on and hood-off comparisons as described below. When measuring emission rates from ovens, we ensured that the oven was empty. When measuring burners, we placed the same stainless-steel pot with tap water on every burner analyzed across all houses (i.e., the same pot for every burner or hob measurement). The pot contained only water and, to avoid introducing potential volatiles from detergents, was not washed between emissions factor measurements. Using a nonemitting induction cooktop, we verified that tap water emits no detectable benzene when boiled. No people were present in kitchens during measurements except for <30 s to turn on the burner or oven or for scenarios that involved cooking food. When we measured emissions from cooking food, we typically had someone in the kitchen for the duration of the measurement to stir and prevent the food from burning. People do not exhale amounts of benzene that would be detectable in kitchen air. (43)

Statistics

We calculated mean and median 95% confidence intervals from a 25,000 replicate bootstrap as described previously (Lebel et al.). (2) We generated each replicate sample in the bootstrap by randomly sampling with replacement of the set of emission factors in question to form a random sample of equal size to the set of emission factors in question. For instance, the bootstrap for gas burners on high consisted of 25,000 replicates of size 54, generated by randomly sampling (with replacement) the set of 54 emission rates for gas burners on high. We then calculated 95% CIs for the means and medians of these bootstraps. (44,45) We used an analogous methodology to measure benzene emissions from electric, induction, and propane stoves, with replicate sizes equal to our sample size in each category. For stove emissions, we calculated statistical significance between groups using the two-sided Mann–Whitney U test (also known as the Wilcoxon rank-sum test). For emissions from food, we calculated significance relative to zero using the two-sided Student’s t-test (because measurement uncertainty could lead to negative values). Sample sizes for each category are summarized in Table 1.
Table 1. Summary of Sample Sizes for Each Cooktop Element and Oven Type
 burners on highburners on lowovens
gas544347
propane11109
coil/radiant/electric14918
induction139N/A

Controlled-Release Validation

Prior to our sampling campaign, we validated our benzene measurement methods using controlled-release experiments. We injected 1.5 and 10 ppmv benzene standards at known flow rates ranging from 150 mL min–1 to 5 L min–1 of the standard into two unoccupied chambers with volumes of 27,200 and 30,050 L. This process produced benzene concentrations typical of values that we observed in kitchens during combustion by gas stoves. The slope of our calculated emission rate divided by the known emission rate was statistically indistinguishable from one (slope = 0.992, standard error of the slope = 0.08, r2 = 0.94, p value of the line fit ≪ 0.01; see Figure S9).

Benzene Concentration Measurements in Air

In addition to measuring emission rates as described above, we also measured benzene concentrations in kitchens and bedrooms for various stove-use scenarios. The kitchen benzene concentrations described in the section “Benzene Concentrations in Home Air” were measured in 17 “unsealed” kitchens (see Definitions above). Because we sometimes tested more than one burner or oven in each kitchen (always separately), we have a total of 33 kitchen benzene concentration measurements. Additionally, the long 8-h time course benzene concentrations reported in the section “Benzene Migration to Bedrooms” were measured in open kitchens (see Definitions above) in 6 different houses. We did not use fans or other means of active air circulation during the long 8-h time courses. In all six houses for which we did the 8-h time courses, we set the oven to 475 °F, a temperature commonly used to bake bread, for 1.5 h with the hood off. We continued monitoring benzene concentrations for 6.5 more hours in the farthest bedroom from the kitchen after turning the oven off.

Benzene Emissions from Fuel Burned to Cook a Single Meal on a Gas Range

We estimated the amount of benzene emitted by gas combustion associated with cooking a single meal based on median benzene emission factors from gas stoves reported here and from previous research tracking usage of cooktops (burners) and ovens in 70 California homes (7) (see the Supporting Information).

National Scale-Up of Emissions

To estimate the amount of benzene emitted by gas combustion in all stoves annually in the United States, we calculated the mean benzene emission factor (ng C6H6 J–1 gas burned) for ovens and burners on high using the flow rate of CO2 and the enthalpy of combustion of methane to calculate the joule (J) of energy emitted per unit time. We calculated the 95% CI using a 25,000 replicate bootstrap (see above). We then multiplied this emission factor and 95% CI by the 2015 Residential Energy Consumption Survey estimate (11) of annual natural gas burned for residential cooking in the United States to reach our annual estimate of benzene emissions from gas combustion in stoves. This estimate is based on the assumption that most gas used for cooking is consumed by ovens or by burners on high. If we instead assumed that more gas is consumed by burners on low, our mean estimate would increase by 30% because we found that burners on low emit more benzene per joule of natural gas consumed than the amount that burners on high emit.

Emissions from Cooking Food and Leakage of Unburned Gas

We measured benzene emissions from cooking meals on two induction cooktops that we determined had zero detectable benzene emissions (see Figure S3). Any benzene emissions could then be attributed to cooking food rather than to the cooktop or fuel used. We cooked two meals, pan-fried fish and bacon, selected because previous research showed particulate and polyaromatic hydrocarbon emissions from frying these foods to be relatively high. (46) We cooked fish with approximately one tablespoon of olive oil as well as bacon in its own grease, both on medium heat in a stainless-steel pan with regular flipping. We cooked three replicates of each meal for 20–35 min until they were “well done” (see Figure S3) to understand the maximum potential emissions of benzene. We calculated p values relative to zero using the two-sided Student’s t-test.
We calculated benzene emission rates attributable to leakage of uncombusted gas using published data on gas stove leakage rates, (2) data on benzene concentrations in natural gas in California, (41) and the following equation from Lebel et al. (2) (adapted from Marrero et al. (42)):
Ebenzene=Emethane×Cbenzene(MWbenzeneMWmethane)
where Ebenzene is the emission rate of benzene, Emethane is the emission rate of methane, Cbenzene is the mole fraction of benzene in the leaked gas, MWbenzene is the molecular weight of benzene, and MWmethane is the molecular weight of methane.

Results

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Benzene Emissions from Combustion

Benzene emissions from gas and propane burners and ovens were substantial (Table 2), nonzero (p < 0.01 for each; Table S1), and repeatable (coefficient of variation = 11% for replicates of gas ovens at 350 °F and gas burners on high up to three months apart). Mean benzene emission rates from gas burners on high and from ovens set to 350 °F were 2.8 [95% confidence interval (CI): 1.7, 4.6] and 5.8 [95% CI: 3.3, 9.7] μg C6H6 min–1, respectively (Table 2). Mean benzene emissions from propane burners on high and ovens set to 350 °F were 5.5 [95% CI: 1.2, 11.0] and 6.5 [95% CI: 2.1, 12.6] μg min–1, respectively (Table 2). Flames from higher-molecular-weight propane produce more benzene in the laboratory than flames from methane per joule, (25) so it would not be surprising if future stove studies with larger sample sizes find that propane stoves emit more benzene than gas stoves. With our dataset, however, we find that while the central estimates of mean benzene emissions from propane burners and from ovens were higher than from their gas counterparts, benzene emissions from gas and propane stoves were nevertheless statistically indistinguishable (p > 0.20 for each pairwise comparison). Median benzene emissions were lower than mean emissions for both gas and propane stoves (Table 2) because emission distributions tended to be long-tailed (Figure 1). Grouping stoves by absolute power output (>1 kW and <1 kW) yielded similar results to grouping by relative power output shown on burners (high vs low, Table S3 and Figure S12).

Figure 1

Figure 1. Mean and median benzene emissions by fuel type (left panels; induction, coil, natural gas, and propane) and emissions from individual cooktop elements and ovens (right panels) in μg C6H6 min–1 by appliance type (gas, coil/radiant, or induction) for burners on high (a,b) or on low (c,d) and for ovens set to 350 °F (e,f). The red points inside the bars in plots a, c, and e are the median values. Bar heights are the mean values, and black error bars are the 95% confidence interval of the mean (calculated as described in methods; see Table S1 for p values). Benzene emission rates were measured directly using the AROMA analyzer (see methods). Burners on “High” in panels a and b refer to the highest-power cooktop element on each stove set to its highest setting; “Low” refers to the lowest-power cooktop element on each stove set to its lowest functional setting. Oven emission rates include the oven preheat and oven cycling (to maintain its temperature) over the 45 m sampling interval. Note the y-axis breaks in panels b, d, and f.

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Table 2. Benzene Emission Rates per Stove Type (μg C6H6 min–1)a
 medianlower boundupper boundmeanlower boundupper bound
propane ovens at 350 °F3.890.4012.56.462.0512.5
propane burners on high1.910.147.085.481.2011.0
gas ovens at 350 °F1.911.333.765.823.269.70
gas burners on high1.340.942.012.781.654.55
propane burners on low0.470.181.023.980.2811.0
coils and radiant on high0.240.060.380.280.130.44
gas burners on low0.210.160.270.470.260.73
electric ovens at 350 °F0.11–0.020.180.230.030.52
induction hobs on high0.04–0.060.170.01–0.130.12
coils and radiant on low0.00–0.100.080.01–0.050.09
induction hobs on low–0.02–0.160.11–0.02–0.230.23
a

Median and 95% confidence interval from 2.5 to 97.5%; mean and 95% confidence interval from 2.5 to 97.5%, calculated with a 25,000 replicate bootstrap (see methods). Mean benzene emission rates for induction hobs on low and high as well as electric coils and radiant hobs on low were statistically indistinguishable from zero.

Expressed per joule (see methods), mean emissions from gas burners on high were 0.014 [95% CI: 0.009, 0.021] μg C6H6 kJ–1, roughly one quarter the emissions per joule from ovens set to 350 °F (Figure S5). Mean emissions normalized per joule for burners on low were higher on average than for both ovens and burners on high but more variable: 0.080 [95% CI: 0.017, 0.192] μg kJ–1. These benzene emission factors correspond to approximately 100 [95% CI: 70, 190] μg benzene per meal cooked on a gas stove for a typical meal cooked using one burner on “high”, one on “low”, and the oven on 350 °F each for approximately 30 min (see methods). We observed no statistically significant relationship between benzene emissions and stove brand or age (see Figure S10).
Benzene emissions from gas and propane burners and ovens were significantly greater than those from electric alternatives (Table 2 and Figure 1; p < 0.01 for all gas-electric comparisons, propane vs induction, and propane vs electric oven; p = 0.075 for propane vs coil/radiant on high; see Table S1). Benzene emissions from induction hobs on high were statistically indistinguishable from zero (p > 0.2; Table 2 and Figure 1a). Mean benzene emissions from coils and radiant hobs on high (grouped together) and from electric ovens were 0.28 [95% CI: 0.15, 0.42] and 0.23 [95% CI: 0.04, 0.52] μg C6H6 min–1, respectively, or 10 and 4% of the emissions from their gas counterparts (Table 2). Benzene emissions from electric coils, radiant stoves, and electric ovens may occur because of organic matter burning off the red-hot (> 500 °C) surface.

Benzene Concentrations in Home Air

We quantified kitchen benzene concentrations after stove use in a 17-home subset of our emission factor sample (using 33 distinct burner and oven measurements; see methods). A single gas or propane burner on high or oven set to 350 °F for 45 min raised kitchen benzene concentrations above the baseline in every kitchen that we tested (Figure 2). This result suggests that gas stoves can contribute substantively to elevated benzene concentrations indoors. Additionally, in 9 of the 33 cases (29%), a single gas burner on high or an oven set to 350 °F raised kitchen benzene concentrations above the upper range of indoor benzene concentrations attributable to secondhand tobacco smoke (0.34–0.78 ppbv) (10) and above the median indoor benzene concentration measured in the US, Canada, Western Europe, Japan, South Korea, Hong Kong, and Australia (0.78 ppbv). (47)

Figure 2

Figure 2. Benzene concentrations in unsealed kitchens as measured immediately after being aired out with outdoor air (mustard circles) and after 45 min with one burner on high or oven set to 350 °F fueled by propane (brown triangles) or gas (orange circles). Each point represents a single measurement; each x-value represents a single kitchen; multiple dots in the same column represent measurements of different burners or ovens in the same kitchen. These measured kitchen concentrations are compared with the upper estimate of benzene concentrations attributable to secondhand tobacco smoke (10) (0.78 ppbv) and the median indoor benzene concentration in the US, Canada, Western Europe, Japan, South Korea, Hong Kong, and Australia derived from a literature survey (47) (0.79 ppbv).

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Benzene Migration to Bedrooms

To quantify the dispersion of pollutants from kitchens to bedrooms, we measured ambient benzene concentrations in bedrooms farthest from open kitchens of six houses (without using fans to mix the air) under a scenario with the oven set to 475 °F for an hour and a half and then turned off while measurements continued for another 6.5 h. During these measurements, we kept interior doors open (see Figure S1 for floorplans of the houses). House 1 (90 m2) had a gas oven with the highest emissions that we measured, houses 2 (85 m2) and 3 (70 m2) had ovens with emissions between the mean and maximum, fueled by propane and gas, respectively, houses 4 (75 m2) and 5 (140 m2) had gas ovens with near-mean emissions, and house 6 (85 m2) had a gas oven with below-average benzene emissions. In all six cases tested, burner or oven use elevated peak bedroom benzene concentrations between 5 and 70 times above baseline levels and in some cases beyond the California OEHHA acute and chronic RELs (Figure 3). (8)

Figure 3

Figure 3. Benzene concentrations (ppbv C6H6) measured in bedrooms furthest from open kitchens with the oven set to 475 °F for 1.5 h and then turned off for 6.5 h. Each point represents a single reading from the AROMA analyzer, and all data points collected are illustrated in the plot. Air-sampling hoses in houses 1, 3, 4, 5, and 6 were placed in bedrooms ∼8 meters down the hall from the kitchen; the sampling hose in house 2 was in a bedroom ∼4 meters down the hall from the kitchen. The solid black line at 1 ppbv benzene represents the California OEHHA 8-h REL for noncancer effects; (8) the solid black line at 8 ppbv benzene represents the California OEEHA acute REL. (8) Several chronic benzene standards are plotted for comparison at the right with dashed black lines for Israel (54) and France (55) at the bottom (0.41 and 0.63 ppbv, respectively), two of the lowest chronic benzene standards globally; the European Union chronic health benchmark (1.56 ppbv), which is the most common chronic health benchmark globally; (9) and, at the top, the chronic standard adopted by the US ATSDR (3.0 ppbv), a department affiliated with the Centers for Disease Control and Prevention. (56) We measured all concentrations in real time using the AROMA VOC analyzer. During the measurements, all interior doors of the houses were open, and no fans were used to mix the air.

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In house 1, bedroom benzene concentrations peaked at 8.9 ppbv, slightly below the maximum value observed in the kitchen of 11.6 ppbv, and remained above the California OEHHA acute REL of 27 μg/m3 (8 ppbv) for >20 min (Figure 3). By comparison, in 2020, there were two separate incidents in which benzene concentrations near schools in Greater Los Angeles and the Colorado Front Range reached between 8.84 and 15.3 ppbv, respectively. (48,49) These benzene measurements prompted local and state news coverage and investigations by authorities. (50,51) Benzene concentrations in house 1 also remained above the California OEHHA 8-h and chronic REL of 3 μg/m3 (1 ppbv) for more than 5 h (Figure 3), and the 8-h time-averaged bedroom benzene concentration (2.8 ppbv) in house 1 was 23 times higher than the baseline bedroom benzene concentration prior to stove use.
Peak benzene concentrations that we measured in other houses were also substantially elevated over background but lower than in house 1. In house 2, bedroom benzene concentrations peaked at 4.2 ppbv and remained elevated above the California OEHHA 8-h REL for the entire duration of the 8-h measurement (Figure 3); the time-averaged bedroom benzene concentration over the 8-h time course was 2.4 ppbv, 26 times higher than the baseline benzene concentration. In house 3, bedroom benzene concentrations peaked at 2.9 ppbv and remained elevated above the California OEHHA 8-h REL for more than 5 h (Figure 3). In houses 4, 5, and 6, with lower benzene emission rates, benzene concentrations in bedrooms during the oven test peaked at 0.69, 0.78, and 0.70 ppbv, respectively (Figure 3).
Ventilation and hood use affect benzene concentrations. Surveys show that ventilation hoods are used by residents only 25–40% of the time. (52) We tested the efficacy of kitchen range hoods by comparing concentrations with two outside-venting hoods on and off in houses 1 and 4. In house 1, kitchen benzene concentrations exceeded the California OEHHA 8-h and chronic REL, 3 μg/m3 (1 ppbv), within 1 h of stove use whether the hood was off or on high (Figure S2). The comparison of hood-on high vs hood-off demonstrates that residential range hoods are not always effective at reducing pollutant concentrations, even if they vent outdoors, as highlighted in previous research. (52)
It is useful to compare other benzene sources to the benzene emissions that we observed attributable to combustion from gas stoves. With stricter emission control measures, benzene concentrations have fallen in many parts of the world over recent decades. For instance, average outdoor benzene concentrations in California fell from 2.5 ppbv in 1990 to 0.3 ppbv in 2012. (53) The indoor benzene concentrations that we measured resulting from combustion by gas stoves are thus substantial relative to ambient concentrations in many parts of the world, especially Europe and the Americas. (9) Unfortunately, however, high benzene concentrations persist in other parts of the world; throughout the 2000s and 2010s, benzene concentrations exceeding 10 ppbv were often measured in several East and South Asian cities, and concentrations exceeding 100 ppbv have been reported in Mumbai, India. (9) In places with extremely high benzene pollution, other larger benzene sources (such as from burning solid fuels (30)) may be more important than pollution from gas stoves.

Benzene Emissions from Food and from Unburned Gas

Benzene emissions from cooking include combustion-related emissions from the stove, potential emissions from food as it cooks, and any emissions from unburned gas leaking from or near the stove (because gas entering homes has been shown to often contain benzene). (41,57) To isolate emissions produced from food while cooking from those associated with fuel combustion, we cooked two meal types on induction cooktops that we determined had benzene emissions indistinguishable from zero. We chose these two foods, fish and bacon, because a previous study found that pan-frying these foods on a gas cooktop produced more polycyclic aromatics (which, like benzene, are partial-combustion products) than any other foods or cooking conditions that the authors tested. (46) Benzene emissions from the foods that we evaluated were indistinguishable from zero (p > 0.35; Figure S3). Our results for these foods suggest that the benzene produced when cooking with gas and propane comes from the fuel burned and not from the food being cooked, at least for these two common meal types. Future research on a broader suite of meal types is warranted.
Benzene emissions from gas use also come from any unburned gas that leaks into the kitchen and that contains trace levels of benzene. (41) Recent studies that sampled uncombusted gas directly from residential stoves in Boston and California measured the concentrations of benzene and other hazardous air pollutants in the gas delivered to homes. (41,57) Assuming that gas is 95% methane, a stove leaking gas with a median benzene concentration for California (1.6 ppmv) (41) at the median rate (24 mg methane h–1) (2) would emit 0.003 μg min–1 of benzene. Such a steady-state off emission of benzene in the smallest kitchen partition that we measured (8.3 m3) with no air exchange would result in an undetectable concentration increase over our 45 min measurement period using our AROMA analyzer. In contrast, we measured median benzene emissions from gas combustion in burners on high and on low and from ovens that are 450, 70, and 640 times greater than this median steady-state off leak rate (Table 2). Thus, typical benzene emission rates attributable to such gas leakage are small relative to the emission rates we measured attributable to gas combustion.

Benzene Emissions as Partial-Combustion Products

When gas burns in a fuel-rich (oxygen-poor) flame, it does not combust fully to water and carbon dioxide. Some partial-oxidation products known to form under these conditions include carbon monoxide, formaldehyde, polycyclic aromatics, and monocyclic aromatics such as benzene. (25) We hypothesized that benzene and carbon monoxide emissions would therefore be correlated, which turned out to be correct (r2 = 0.67, p < 0.01, Figure S4). This relationship suggests that both benzene and carbon monoxide may be produced in similar partial-combustion conditions in gas and propane stoves and ovens. Similarly, other unstudied partial-combustion pollutants could also be produced, a possibility that warrants future research.

Benzene Emissions from Gas Combustion in Stoves Compared with Current EPA Estimates and Other Benzene Sources

Our results suggest that the U.S. EPA substantively underestimates benzene emissions from total residential gas combustion. Our results show that gas burners on high and gas ovens set to 350 °F (grouped together) emit 0.059 [95% CI: 0.037, 0.088] μg benzene kJ–1 gas burned. Scaling up our measured emission factor, we estimate that ∼7200 [95% CI: 4200, 12,800] kg of benzene is emitted by gas combustion by stoves alone in the U.S. annually (see methods). In contrast, the EPA’s National Emissions Inventory estimates that all residential gas appliances (including furnaces and water heaters) emit 4300 kg of benzene in total annually, (58) slightly more than half of our estimate for stoves alone. This discrepancy likely arises because the EPA measured benzene emission factors from utility-scale boilers rather than from home appliances and used these values to calculate residential emissions. (29,58,59) The EPA’s boiler-derived benzene emission factor for natural gas combustion of 2.1 × 10–3 lb benzene per 106 standard cubic foot of gas (0.0009 μg benzene kJ–1 gas burned) (29) is 65 times lower than our estimate. The EPA relies on the same boiler-derived benzene emission factor to estimate emissions from water heaters, furnaces, and stoves. If the benzene emission factors from water heaters and furnaces are similar to those from stoves, then the discrepancy between current EPA estimates and true benzene emissions due to residential gas combustion may be even higher than presented here.
The total quantity of benzene emitted attributable to gas combustion in stoves is small relative to some other large benzene sources but could have a disproportionate effect on health because the benzene from combustion is emitted directly indoors. According to the EPA, the largest sources of benzene in the U.S. are wildfires (45 million kg year–1), gasoline-powered light-duty vehicles (37 million kg year–1), and oil and gas production (25 million kg year–1). (60) Large sources of benzene should certainly be minimized wherever possible, but benzene emitted outdoors can quickly dissipate and degrade. (61) As a result, outdoor and indoor benzene emissions are not directly comparable for their health effects on a kg-for-kg basis.

Study Implications and Suggestions for Future Research

Gas stoves are common in U.S. homes and around the world, and their emissions can alter the indoor air quality of people who live and work around them. (2,7,11−13,20,21,62) We quantified benzene emission factors from combustion in gas and propane stoves, to our knowledge for the first time. Our findings suggest that the concentrations of benzene produced by combustion from gas stoves and ovens indoors may increase health risks under some conditions. Further research is needed to assess actual exposures and the full health impacts of benzene emitted indoors from combustion by gas stoves. We also showed that using a gas burner or oven may increase kitchen and bedroom benzene concentrations above chronic exposure guidelines, depending on ventilation conditions and home size. By measuring benzene concentrations in bedrooms during and after gas burner and oven use, we also showed that benzene produced from gas stoves migrates well beyond the kitchen. People outside the kitchen can be exposed to elevated levels of benzene for hours after the stove is turned off.
Our work also shows that gas and propane fuels appear to be the dominant source of benzene produced by cooking. We found that benzene emissions from induction stoves and from cooking food were undetectable (i.e., statistically indistinguishable from zero), at least for the two meals that we evaluated. We further found that mean emissions from electric coils and radiant hobs on high and electric ovens on 350 °F were 10- to 25-fold smaller than emissions from gas and propane stoves. Average emissions from coils and radiant hobs on low were statistically indistinguishable from zero.
To understand and model benzene exposure indoors, researchers need emission rates, as we provide here, and better data for stove use, hood use, and hood type. For instance, researchers have very little data on how often multiple burners are used simultaneously, how often burners and ovens are used together, and how frequently the oven is used to heat the home (a practice that is not recommended but that we nevertheless encountered multiple times during our home surveys).
A better understanding of indoor pollutants and air quality is also needed, in part because people spend much of their time indoors. One study of 1760 California residents, for instance, determined that people spent 87% of their time indoors. (63) Our results show that gas and propane combustion by stoves emits benzene directly into indoor air. These results highlight the importance of combustion by gas stoves for indoor air quality and human exposure in future policies designed to protect people from air pollution, particularly people in lower-income neighborhoods with smaller home sizes.

Supporting Information

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The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.est.2c09289.

  • Additional details for air exchange calculations and assumptions underlying calculations of benzene emissions from a single meal; table of p-values for pairwise comparisons of benzene emissions from gas and propane burners on high, on low, and from ovens; summary of attributes of all stoves measured and locations sampled for the study, including the map of sampling locations; floorplans of houses in which bedroom benzene concentrations were measured; kitchen benzene concentrations measured with a hood on and off; photo showing the setup and plot showing results for measurement of benzene emissions from food cooked on an induction stove; benzene emissions from gas stoves plotted against accompanying carbon monoxide emissions; benzene emissions expressed per joule of gas burned; kitchen chamber volumes used in emission rate measurements; image of the sampling setup for emission rate measurements; calculated and actual benzene emissions rates from controlled-release tests; benzene emissions by stove age and brand; gas and propane burner power output; benzene emissions from propane stoves grouped by absolute power output (PDF)

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Author Information

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  • Corresponding Author
    • Robert B. Jackson - Earth System Science Department, Stanford University, 473 Via Ortega, Stanford, California 94305, United States;  Woods Institute for the Environment and Precourt Institute for Energy, Stanford, California 94305, United States;  Orcidhttps://orcid.org/0000-0001-8846-7147;  Email: [email protected]
  • Authors
    • Yannai S. Kashtan - Earth System Science Department, Stanford University, 473 Via Ortega, Stanford, California 94305, United States;  Orcidhttps://orcid.org/0000-0001-6323-1533
    • Metta Nicholson - Earth System Science Department, Stanford University, 473 Via Ortega, Stanford, California 94305, United States;  Orcidhttps://orcid.org/0000-0002-3145-7922
    • Colin Finnegan - Earth System Science Department, Stanford University, 473 Via Ortega, Stanford, California 94305, United States;  Orcidhttps://orcid.org/0000-0003-2619-2584
    • Zutao Ouyang - Earth System Science Department, Stanford University, 473 Via Ortega, Stanford, California 94305, United States;  Orcidhttps://orcid.org/0000-0002-6919-569X
    • Eric D. Lebel - PSE Healthy Energy, 1140 Broadway, Suite 750, Oakland, California 94612, United States;  Orcidhttps://orcid.org/0000-0001-5255-6893
    • Drew R. Michanowicz - PSE Healthy Energy, 1140 Broadway, Suite 750, Oakland, California 94612, United States;  Orcidhttps://orcid.org/0000-0002-2538-4819
    • Seth B.C. Shonkoff - PSE Healthy Energy, 1140 Broadway, Suite 750, Oakland, California 94612, United States;  Environmental Health Sciences, School of Public Health, University of California, Berkeley, Berkeley, California 94720, United States;  Energy Technologies Area, Lawrence Berkeley National Lab, Berkeley, California 94720, United States;  Orcidhttps://orcid.org/0000-0002-2696-0259
  • Author Contributions

    R.B.J., S.B.C.S., and Y.S.K. conceived the project. Y.S.K., M.N., C.F., Z.O., R.B.J., and E.D.L. developed the methods for the project. Y.S.K., M.N., C.F., and Z.O. performed most of the field measurements. E.D.L. and D.R.M. assisted with methods and data interpretation. Y.S.K. wrote the manuscript with assistance from R.B.J., and all authors edited the final version. R.B.J. supervised the project.

  • Notes
    The authors declare no competing financial interest.

Acknowledgments

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We thank Tony Miller from Entanglement Technologies for assistance with the AROMA VOC analyzer. We also thank Janet Herrera and Kevin Hamilton of the Central California Asthma Coalition for help identifying homes to sample in Bakersfield, CA. We acknowledge the High Tide Foundation for primary support of our research.

References

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    Friedlingstein, P.; Jones, M. W.; O’Sullivan, M.; Andrew, R. M.; Bakker, D. C. E.; Hauck, J.; Le Quéré, C.; Peters, G. P.; Peters, W.; Pongratz, J.; Sitch, S.; Canadell, J. G.; Ciais, P.; Jackson, R. B.; Alin, S. R.; Anthoni, P.; Bates, N. R.; Becker, M.; Bellouin, N.; Bopp, L.; Chau, T. T. T.; Chevallier, F.; Chini, L. P.; Cronin, M.; Currie, K. I.; Decharme, B.; Djeutchouang, L. M.; Dou, X.; Evans, W.; Feely, R. A.; Feng, L.; Gasser, T.; Gilfillan, D.; Gkritzalis, T.; Grassi, G.; Gregor, L.; Gruber, N.; Gürses, Ö.; Harris, I.; Houghton, R. A.; Hurtt, G. C.; Iida, Y.; Ilyina, T.; Luijkx, I. T.; Jain, A.; Jones, S. D.; Kato, E.; Kennedy, D.; Goldewijk, K. K.; Knauer, J.; Korsbakken, J. I.; Körtzinger, A.; Landschützer, P.; Lauvset, S. K.; Lefèvre, N.; Lienert, S.; Liu, J.; Marland, G.; McGuire, P. C.; Melton, J. R.; Munro, D. R.; Nabel, J. E. M. S.; Nakaoka, S.-I.; Niwa, Y.; Ono, T.; Pierrot, D.; Poulter, B.; Rehder, G.; Resplandy, L.; Robertson, E.; Rödenbeck, C.; Rosan, T. M.; Schwinger, J.; Schwingshackl, C.; Séférian, R.; Sutton, A. J.; Sweeney, C.; Tanhua, T.; Tans, P. P.; Tian, H.; Tilbrook, B.; Tubiello, F.; van der Werf, G. R.; Vuichard, N.; Wada, C.; Wanninkhof, R.; Watson, A. J.; Willis, D.; Wiltshire, A. J.; Yuan, W.; Yue, C.; Yue, X.; Zaehle, S.; Zeng, J. Global Carbon Budget 2021. Earth Syst. Sci. Data 2022, 14, 1917– 2005,  DOI: 10.5194/essd-14-1917-2022
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    Lebel, E. D.; Lu, H. S.; Speizer, S. A.; Finnegan, C. J.; Jackson, R. B. Quantifying Methane Emissions from Natural Gas Water Heaters. Environ. Sci. Technol. 2020, 54, 5737– 5745,  DOI: 10.1021/acs.est.9b07189
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    Quantifying Methane Emissions from Natural Gas Water Heaters
    Lebel, Eric D.; Lu, Harmony S.; Speizer, Simone A.; Finnegan, Colin J.; Jackson, Robert B.
    Environmental Science & Technology (2020), 54 (9), 5737-5745CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Natural gas appliance CH4 emissions are the least characterized portion of the fossil fuel supply chain. This work examd. water heaters from 64 northern California homes to: quantify CH4 emissions from natural gas leaks and incomplete combustion while heater is off, turning on/off, and in steady-state operation from 35 homes; and characterizing daily use patterns over ∼1-2 mo/water heater to est. activity factors from 46 homes. On av., individual tank-less water heaters emitted 2390 (95% confidence interval [CI]: 2250, 2540) g CH4/yr; 0.93% [0.87%, 0.99%] of their natural gas consumed was primarily from on/off pulses. On av., storage water heaters emitted 1400 [1240, 1560] g CH4/yr; 0.39% [0.34%, 0.43%] of their natural gas consumption. Despite higher CH4 emissions, tank-less water heaters generated 29% less CO2e20 than storage water heaters because they used less energy to heat a unit of water. Scaling these measured emissions by no. of storage and tank-less water heaters in the US (56.8 and 1.2 million, resp.), overall, water heaters emitted an estd. 82.3 [73.2, 91.5] Gg CH4/yr, 0.40% [0.35%, 0.44%] of all natural gas consumed by these appliances which is comparable in percentage to USEPA estd. CH4 emissions from upstream natural gas prodn.
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    Merrin, Z.; Francisco, P. W. Unburned Methane Emissions from Residential Natural Gas Appliances. Environ. Sci. Technol. 2019, 53, 5473– 5482,  DOI: 10.1021/acs.est.8b05323
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    Unburned Methane Emissions from Residential Natural Gas Appliances
    Merrin, Zachary; Francisco, Paul W.
    Environmental Science & Technology (2019), 53 (9), 5473-5482CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    CH4, the primary natural gas (NG) component, is a potent greenhouse gas. NG is a common fuel for residential appliances due to low cost, high energy d., and relatively clean combustion. NG combustion gas contains unburned CH4 due to inevitable incomplete combustion. A field campaign measuring CH4 concns. in residential NG appliance exhaust gas was conducted in Boston and Indianapolis to det. its contribution to overall emissions. NG space heating, water heating, and cooking appliances were measured in 100 homes. Appliance exhaust typically exhibited a brief CH4 concn. spike during ignition and extinguishment, and relatively low concns. during steady-state operation. Exceptions to this pattern include ovens, sub-optimal stove burners, and tank-less water heaters, which have a different operating pattern or non-trivial steady-state concns. Results were combined with appliance use and prevalence assumptions to est. total emissions. Annually, ∼30 [97.5% confidence interval [CI]: 19-160] Gg CH4 emissions can be attributed to US residential NG appliances, corresponding to ∼830 [530-4500] Gg CO2 equiv. (CO2e100). This accounts for ∼0.1% [0.08-0.7%] of US anthropogenic CH4 emissions (which account for ∼10% of total US greenhouse gas emissions) and corresponds to an emission factor of 0.38 g/kg NG consumed (0.038% [0.024-0.21%]).
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    Fischer, M. L.; Chan, W. R.; Delp, W.; Jeong, S.; Rapp, V.; Zhu, Z. An Estimate of Natural Gas Methane Emissions from California Homes. Environ. Sci. Technol. 2018, 52, 10205– 10213,  DOI: 10.1021/acs.est.8b03217
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    An Estimate of Natural Gas Methane Emissions from California Homes
    Fischer, Marc L.; Chan, Wanyu R.; Delp, Woody; Jeong, Seongeun; Rapp, Vi; Zhu, Zhimin
    Environmental Science & Technology (2018), 52 (17), 10205-10213CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Post-meter CH4 emissions from the California residential natural gas (NG) system were estd. using measurements and anal. from a sample of homes and appliances. Quiescent, whole-house emissions (i.e., pipe leaks, pilot lights) were measured with a mass balance method in 75 California homes; CH4:CO2 emission ratios were measured for steady operation of individual combustion appliances and, sep., for transient operation of three tank-less water heaters. Measured, quiescent whole-house emissions were typically <1 g CH4/day, though they exhibited long-tailed gamma distributions with values >10 g CH4/day. Most operating appliances yielded undetectable CH4:CO2 enhancements in steady operation (<0.01% of gas consumed), though storage water heaters and stove-tops exhibited long-tailed gamma distributions contg. high values (∼1-3% of gas consumed), and transients were obsd. for tank-less heaters. Extrapolating results to a state-level using Bayesian Markov chain Monte Carlo sampling in conjunction with California housing statistics and gas use information suggested quiescent house leakage of 23.4 (13.7-45.6, at 95% confidence) Gg CH4, with pilot lights contributing ∼30%. Appliance steady state operating emissions and their pilot lights were 13.3 (6.6-37.1) Gg CH4/yr, an order of magnitude larger than current inventory ests., with transients likely further increasing appliance emissions. Together, residential NG emissions were 35.7 (21.7-64.0) Gg CH4/yr, equiv. to ∼15% of the state NG CH4 emissions, suggesting leak repair, improved combustion appliances, and adoption of non-fossil energy heating sources can help California meet its 2050 climate goals.
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    World Health Organization Global Air Quality Guidelines: Particulate Matter (PM2.5 and PM10), Ozone, Nitrogen Dioxide, Sulfur Dioxide and Carbon Monoxide ; 2021. (accessed 2022-07-11).
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    US Environmental Protection Agency Review of the Primary National Ambient Air Quality Standards for Oxides of Nitrogen ; 2018. . (accessed 2022-07-11).
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    Lin, W.; Brunekreef, B.; Gehring, U. Meta-Analysis of the Effects of Indoor Nitrogen Dioxide and Gas Cooking on Asthma and Wheeze in Children. Int. J. Epidemiol. 2013, 42, 1724– 1737,  DOI: 10.1093/IJE/DYT150
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    Meta-analysis of the effects of indoor nitrogen dioxide and gas cooking on asthma and wheeze in children
    Lin Weiwei; Brunekreef Bert; Gehring Ulrike
    International journal of epidemiology (2013), 42 (6), 1724-37 ISSN:.
    BACKGROUND: Since the meta-analysis on the association between indoor nitrogen dioxide (NO2) and childhood respiratory illness in 1992, many new studies have been published. The quantitative effects of indoor NO2 on respiratory illness have not been estimated in a formal meta-analysis since then. We aimed to quantify the association of indoor NO2 and its main source (gas cooking) with childhood asthma and wheeze. METHODS: We extracted the association between indoor NO2 (and gas cooking) and childhood asthma and wheeze from population studies published up to 31 March 2013. Data were analysed by inverse-variance-weighted, random-effects meta-analysis. Sensitivity analyses were conducted for different strata. Publication bias and heterogeneity between studies were investigated. RESULTS: A total of 41 studies met the inclusion criteria. The summary odds ratio from random effects meta-analysis for asthma and gas cooking exposure was 1.32 [95% confidential interval (CI) 1.18-1.48], and for a 15-ppb increase in NO2 it was 1.09 (95% CI 0.91-1.31). Indoor NO2 was associated with current wheeze (random effects OR 1.15; 95% CI 1.06-1.25). The estimates did not vary much with age or between regions. There was no evidence of publication bias. CONCLUSIONS: This meta-analysis provides quantitative evidence that, in children, gas cooking increases the risk of asthma and indoor NO2 increases the risk of current wheeze.
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    Gruenwald, T.; Seals, B. A.; Knibbs, L. D.; Hosgood, H. D., III Population Attributable Fraction of Gas Stoves and Childhood Asthma in the United States. Int. J. Environ. Res. Public Health 2023, 20, 75,  DOI: 10.3390/IJERPH20010075
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    Jin, H.; Frassoldati, A.; Wang, Y.; Zhang, X.; Zeng, M.; Li, Y.; Qi, F.; Cuoci, A.; Faravelli, T. Kinetic Modeling Study of Benzene and PAH Formation in Laminar Methane Flames. Combust. Flame 2015, 162, 1692– 1711,  DOI: 10.1016/j.combustflame.2014.11.031
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    Kinetic modeling study of benzene and PAH formation in laminar methane flames
    Jin, Hanfeng; Frassoldati, Alessio; Wang, Yizun; Zhang, Xiaoyuan; Zeng, Meirong; Li, Yuyang; Qi, Fei; Cuoci, Alberto; Faravelli, Tiziano
    Combustion and Flame (2015), 162 (5), 1692-1711CODEN: CBFMAO; ISSN:0010-2180. (Elsevier B.V.)
    Methane is probably the most frequently studied hydrocarbon fuel. Both its oxidn. mechanism and its pyrolysis to higher-mass products have received considerable attention. In order to have a glance into the combustion chem. of methane, a detailed kinetic model was developed to reproduce the fuel decompn. and the formation of benzene and PAHs in laminar methane flames. The model was validated against the exptl. data from previous works on premixed flames, counter flow diffusion flames, and finally the coflow diffusion flames exptl. investigated in this work. Reaction pathway anal. highlights the combustion kinetics of methane in various flame conditions, including the differences in fuel consumption paths, and the formation of low mol. wt. species, benzene and PAHs. C2-C4 species are important intermediates in the combustion of methane, which significantly control the formation of larger mols. and the emission of pollutants. Resonantly stabilized free radicals, such as propargyl, benzyl and indenyl radicals are major PAH precursors, but other arom. radicals like Ph and naphthyl radicals also play a significant role. Their self-recombination reactions or the addn. reactions on small hydrocarbon intermediates (e.g., C2 species) are effective arom. grown pathways in laminar methane flames.
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    Senkan, S. Formation of Polycyclic Aromatic Hydrocarbons (PAH) in Methane Combustion: Comparative New Results from Premixed Flames. Combust. Flame 1996, 107, 141– 150,  DOI: 10.1016/0010-2180(96)00044-2
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    Formation of polycyclic aromatic hydrocarbons (PAH) in methane combustion: comparative new results from premixed flames
    Senkan, Selim; Castaldi, Marco
    Combustion and Flame (1996), 107 (1/2), 141-150CODEN: CBFMAO; ISSN:0010-2180. (Elsevier)
    Direct sampling and gas chromatog.-mass spectral anal. of fuel-rich, laminar, premixed flames of CH4 indicated the prodn. of higher in-flame peak concns. of benzene and polycyclic arom. hydrocarbons (PAH) than in the flames of ethane under similar combustion conditions. These findings were surprising and significant because the methane flame not only has a higher H/C ratio and lower carbon d., but also contained an odd no. of carbon atoms, and produced the least amt. of acetylene. These findings had implications in PAH formation as well as in soot surface reactions in hydrocarbon flames. C4H2 and C3H4 species were implicated as intermediates in benzene formation.
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    Cuoci, A.; Frassoldati, A.; Faravelli, T.; Jin, H.; Wang, Y.; Zhang, K.; Glarborg, P.; Qi, F. Experimental and Detailed Kinetic Modeling Study of PAH Formation in Laminar Co-Flow Methane Diffusion Flames. Proc. Combust. Inst. 2013, 34, 1811– 1818,  DOI: 10.1016/j.proci.2012.05.085
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    Experimental and detailed kinetic modeling study of PAH formation in laminar co-flow methane diffusion flames
    Cuoci, Alberto; Frassoldati, Alessio; Faravelli, Tiziano; Jin, Hanfeng; Wang, Yizun; Zhang, Kuiwen; Glarborg, Peter; Qi, Fei
    Proceedings of the Combustion Institute (2013), 34 (1), 1811-1818CODEN: PCIRC2; ISSN:1540-7489. (Elsevier B.V.)
    In the present paper, synchrotron VUV photoionization mass spectrometry is used to study the detailed chem. of co-flow methane diffusion flames with different diln. ratios. The exptl. results constitute a comprehensive characterization of species important for PAH and soot formation under conditions that resemble those of practical flames. In addn. to the main C1/C2 species, unsatd. C3 (C3H2, C3H3, aC3H4, pC3H4), C4 (C4H2, C4H4, C4H6), and C6 (C6H2) species as well as first aroms. (C6H6, C7H8, C10H8, C12H8) are detected. The laminar, co-flow flames were simulated using an original CFD code based on the operator-splitting technique, specifically conceived to handle large kinetic mechanisms. The detailed kinetic modeling was effectively used to describe and analyze the fuel consumption and the formation of PAH. Exptl. measurements and numerical predictions were found to be in satisfactory agreement and showed the relative importance of the C2 and C3 mechanisms in the formation of the first aroms.
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    Georganta, E.; Rahman, R. K.; Raj, A.; Sinha, S. Growth of Polycyclic Aromatic Hydrocarbons (PAHs) by Methyl Radicals: Pyrene Formation from Phenanthrene. Combust. Flame 2017, 185, 129– 141,  DOI: 10.1016/j.combustflame.2017.07.011
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    Growth of polycyclic aromatic hydrocarbons (PAHs) by methyl radicals: Pyrene formation from phenanthrene
    Georganta, Evgenia; Rahman, Ramees K.; Raj, Abhijeet; Sinha, Sourab
    Combustion and Flame (2017), 185 (), 129-141CODEN: CBFMAO; ISSN:0010-2180. (Elsevier B.V.)
    The formation of polycyclic arom. hydrocarbons (PAHs) in high temp. environments is an ongoing area of research due to the mismatch between the exptl. and simulated concn. profiles of PAHs in several flames. In this work, the role of Me radicals in the growth of PAHs is identified by developing a detailed reaction mechanism for the conversion of phenanthrene to pyrene by Me radicals. The reaction energetics are obtained through quantum calcns. using B3LYP and M06-2X functionals along with 6-311++G(d,p) basis set, and are used to compare the competing channels for pyrene formation. The transition state theory is used to det. the reaction kinetics. Through kinetic simulations, the most preferred path for pyrene formation from phenanthrene is detd. To quantify the contribution of the newly found reactions in PAH growth in the presence of other competing PAH mechanisms, the reactions are merged with a recently developed and well-validated mechanism for C1-C4 hydrocarbons with detailed PAH chem. Three premixed laminar aliph. flames were simulated with the updated mechanism. It was obsd. that the new reactions did not appreciably influence the computed profiles of phenanthrene and pyrene. Through the rate-of-prodn. anal., it was found that the phenanthrene radicals created through H-abstraction were more susceptible to attack by C2H2 than by Me radicals. The indirect role of Me radicals in PAH formation and growth is shown.
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    Anosike, C. R. Unhealthy Effects of Gas Flaring and Wayforward to Actualize the Stopping of Gas Flaring in Nigeria. Society of Petroleum Engineers - Nigeria Annual International Conference and Exhibition 2010, NAICE; SPE, 2010, 1, 199– 202.  DOI: 10.2118/136970-MS .
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    US Environmental Protection Agency Emission Factor Documentation for AP-42 Section 1.4 Natural Gas Combustion ; 1998. (accessed 2022-10-23).
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    Zhang, J.; Smith, K. R. Hydrocarbon Emissions and Health Risks from Cookstoves in Developing Countries. J. Exposure Anal. Environ. Epidemiol. 1996, 6, 147– 161
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    Hydrocarbon emissions and health risks from cookstoves in developing countries
    Zhang, Junfeng; Smith, Kirk R.
    Journal of Exposure Analysis and Environmental Epidemiology (1996), 6 (2), 147-161CODEN: JEAEE9; ISSN:1053-4245. (Princeton Scientific)
    Nonmethane hydrocarbon emissions from several types of cookstoves commonly used in developing countries were measured in a pilot study conducted in Manila, the Philippines. Wood, charcoal, kerosene, and liquefied petroleum gas (LPG) were tested. Because kerosene was burned in 3 different types of stoves, there were 6 fuel/stove combinations tested. Fifty-nine nonmethane hydrocarbons were identified frequently in emissions of these cookstoves, with emission ratios to CO2 ≤5.3 × 10-3. The emissions were quantitated with emission factors on both a mass basis (emissions/kg fuel) and a task basis (emissions/cooking task). On a task basis, combustion of biomass fuels (wood and charcoal) generally produced higher emission factors than combustion of fossil fuels (kerosene and LPG). One type of kerosene stove (wick stove), however, still generated the greatest emissions of some individual and classes of hydrocarbons, indicating that emissions were dependent on not only fuel types but also combustion devices. Some hydrocarbons, e.g., benzene, 1,3-butadiene, styrene, and xylenes, were of concern because of their carcinogenic properties. The lifetime risk from exposures to these compds. emitted from cookstoves was tentatively estd. using a simple exposure model and published cancer potencies.
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    Lan, Q.; Zhang, L.; Li, G.; Vermeulen, R.; Weinberg, R. S.; Dosemeci, M.; Rappaport, S. M.; Shen, M.; Alter, B. P.; Wu, Y.; Kopp, W.; Waidyanatha, S.; Rabkin, C.; Guo, W.; Chanock, S.; Hayes, R. B.; Linet, M.; Kim, S.; Yin, S.; Rothman, N.; Smith, M. T. Hematotoxicity in Workers Exposed to Low Levels of Benzene. Science (1979) 2004, 306, 1774– 1776,  DOI: 10.1126/science.1102443
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    Snyder, R. Leukemia and Benzene. Int. J. Environ. Res. Public Health 2012, 9, 2875– 2893,  DOI: 10.3390/IJERPH9082875
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    Leukemia and benzene
    Snyder, Robert
    International Journal of Environmental Research and Public Health (2012), 9 (), 2875-2893CODEN: IJERGQ; ISSN:1660-4601. (MDPI AG)
    A review. Excessive exposure to benzene has been known for more than a century to damage the bone marrow resulting in decreases in the nos. of circulating blood cells, and ultimately, aplastic anemia. Of more recent vintage has been the appreciation that an alternative outcome of benzene exposure has been the development of one or more types of leukemia. While many investigators agree that the array of toxic metabolites, generated in the liver or in the bone marrow, can lead to traumatic bone marrow injury, the more subtle mechanisms leading to leukemia have yet to be critically dissected. This problem appears to have more general interest because of the recognition that so-called "second cancer" that results from prior treatment with alkylating agents to yield tumor remissions, often results in a type of leukemia reminiscent of benzene-induced leukemia. Furthermore, there is a growing literature attempting to characterize the fine structure of the marrow and the identification of so called "niches" that house a variety of stem cells and other types of cells. Some of these "niches" may harbor cells capable of initiating leukemias. The control of stem cell differentiation and proliferation via both inter- and intra-cellular signaling will ultimately det. the fate of these transformed stem cells. The ability of these cells to avoid checkpoints that would prevent them from contributing to the leukemogenic response is an addnl. area for study. Much of the study of benzene-induced bone marrow damage has concd. on detg. which of the benzene metabolites lead to leukemogenesis. The emphasis now should be directed to understanding how benzene metabolites alter bone marrow cell biol.
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    Singer, B. C.; Hodgson, A. T.; Nazaroff, W. W. Gas-Phase Organics in Environmental Tobacco Smoke: 2. Exposure-Relevant Emission Factors and Indirect Exposures from Habitual Smoking. Atmos. Environ. 2003, 37, 5551– 5561,  DOI: 10.1016/J.ATMOSENV.2003.07.015
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    Gas-phase organics in environmental tobacco smoke: 2. Exposure-relevant emission factors and indirect exposures from habitual smoking
    Singer, Brett C.; Hodgson, Alfred T.; Nazaroff, William W.
    Atmospheric Environment (2003), 37 (39-40), 5551-5561CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Science B.V.)
    Sorption of emitted gas-phase org. compds. onto material surfaces affects environmental tobacco smoke (ETS) compn. and exposures indoors. We have introduced a new metric, the exposure relevant emission factor (EREF) that accounts for sorptive uptake and reemission to give the mass of individual ETS constituents available for exposure over a day in which smoking occurs. This paper describes month-long expts. to investigate sorption effects on EREFs and potential ETS exposures under habitual smoking conditions. Cigarettes were smoked in a 50-m3 furnished room over a 3-h period 6-7 days per wk, with continuous ventilation at 0.3, 0.6, or 2.1 h-1. Org. gas concns. were measured every few days over 4-h "smoking", 10-h "post-smoking" and 10-h "background" periods. Concn. patterns of volatile ETS components including 1,3-butadiene, benzene and acrolein were similar to those calcd. for a theor. non-sorbing tracer, indicating limited sorption. Concns. of ETS tracers, e.g. 3-ethenylpyridine (3-EP) and nicotine, and lower volatility toxic air contaminants including phenol, cresols, and naphthalene increased as expts. progressed, indicating mass accumulation on surfaces and higher desorption rates. Daily patterns stabilized after week 2, yielding a steady daily cycle of ETS concns. assocd. with habitual smoking. EREFs for sorbing compds. were higher under steady cycle vs. single-day smoking conditions by ∼50% for 3-EP, and by 2-3 times for nicotine, phenol, cresols, naphthalene, and methylnaphthalenes. Our results provide relevant information about potential indirect exposures from residual ETS (non-smoker enters room shortly after smoker finishes) and from reemission, and their importance relative to direct exposures (non-smoker present during smoking). Under the conditions examd., indirect exposures accounted for a larger fraction of total potential exposures for sorbing vs. non-sorbing compds., and at lower vs. higher ventilation rates. Increasing ventilation can reduce indirect exposures to very low levels for non-sorbing ETS components, but indirect routes accounted for ∼50% of potential nicotine exposures during non-smoking periods at all ventilation rates.
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    Ferrero, A.; Esplugues, A.; Estarlich, M.; Llop, S.; Cases, A.; Mantilla, E.; Ballester, F.; Iñiguez, C. Infants’ Indoor and Outdoor Residential Exposure to Benzene and Respiratory Health in a Spanish Cohort. Environ. Pollut. 2017, 222, 486– 494,  DOI: 10.1016/j.envpol.2016.11.065
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    Infants' indoor and outdoor residential exposure to benzene and respiratory health in a Spanish cohort
    Ferrero, Amparo; Esplugues, Ana; Estarlich, Marisa; Llop, Sabrina; Cases, Amparo; Mantilla, Enrique; Ballester, Ferran; Iniguez, Carmen
    Environmental Pollution (Oxford, United Kingdom) (2017), 222 (), 486-494CODEN: ENPOEK; ISSN:0269-7491. (Elsevier Ltd.)
    Benzene exposure represents a potential risk for children's health. Apart from being a known carcinogen for humans (group 1 according to IARC), there is scientific evidence suggesting a relationship between benzene exposure and respiratory problems in children. But results are still inconclusive and inconsistent. This study aims to assess the determinants of exposure to indoor and outdoor residential benzene levels and its relationship with respiratory health in infants. Participants were 1-yr-old infants (N = 352) from the INMA cohort from Valencia (Spain). Residential benzene exposure levels were measured inside and outside dwellings by means of passive samplers in a 15-day campaign. Persistent cough, low respiratory tract infections and wheezing during the first year of life, and covariates (dwelling traits, lifestyle factors and sociodemog. data) were obtained from parental questionnaires. Multiple Tobit regression and logistic regression models were performed to assess factors assocd. to residential exposure levels and health assocns., resp. Indoor levels were higher than outdoor ones (1.46 and 0.77 μg/m3, resp.; p < 0.01). A considerable percentage of dwellings, 42% and 21% indoors and outdoors resp., surpassed the WHO guideline of 1.7 μg/m3 derived from a lifetime risk of leukemia above 1/100 000. Monitoring season, maternal country of birth and parental tobacco consumption were assocd. with residential benzene exposure (indoor and outdoors). Addnl., indoor levels were assocd. with mother's age and type of heating, and outdoor levels were linked with zone of residence and distance from industrial areas. After adjustment for confounding factors, no significant assocns. were found between residential benzene exposure levels and respiratory health in infants. Hence, our study did not support the hypothesis for the benzene exposure effect on respiratory health in children. Even so, it highlights a public health concern related to the personal exposure levels, since a considerable no. of children surpassed the abovementioned WHO guideline for benzene exposure.
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    Begou, P.; Kassomenos, P. One-Year Measurements of Toxic Benzene Concentrations in the Ambient Air of Greece: An Estimation of Public Health Risk. Atmos. Pollut. Res. 2020, 11, 1829– 1838,  DOI: 10.1016/J.APR.2020.07.011
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    One-year measurements of toxic benzene concentrations in the ambient air of Greece: An estimation of public health risk
    Begou, Paraskevi; Kassomenos, Pavlos
    Atmospheric Pollution Research (2020), 11 (10), 1829-1838CODEN: APRTCD; ISSN:1309-1042. (Elsevier B.V.)
    In this study, the ambient benzene concns. were measured in 7 air quality monitoring stations in Greece. The pollutant measurements were continuously being collected from the air quality monitoring network of the country through a calendar year (from 1st Jan. 2016 to 31st Dec. 2016). The monitoring stations were classified as Urban Traffic, Urban-Industrial, Suburban-Industrial and Urban Background according to the regional type zone. The highest ambient benzene concns. were measured during the winter period while the lowest ones were measured during the summer months. The annual mean values of benzene concns. varied between 0.81 ± 0.56μg/m3 (in Elefsina station) and 5.63 ± 3.68μg/m3 (in Patission station) across the air quality monitoring stations under study. In addn., a health risk assessment was carried out in order to det. the effects of ambient benzene on the population health in Greece, considering both cancer and non-cancer effects. We calcd. the Integrated Lifetime Cancer Risk (ILTCR) assocd. with the inhalation exposure to ambient benzene. Regarding the non-cancer effects, we estd. the Hazard Quotient (HQ) values. Moreover, the quantification of the Environmental Burden of Disease (EBD), due to the exposure to ambient benzene was calcd. considering 4 exposure scenarios. These scenarios were based on the annual benzene concns. detected in the country. Our anal. revealed that the exposure to ambient benzene in Greece causes an amt. of annual Disability-Adjusted Life Years (DALYs) which varied between 0.262 and 0.655 DALYs lost per 100,000 inhabitants.
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    Hazrati, S.; Rostami, R.; Farjaminezhad, M.; Fazlzadeh, M. Preliminary Assessment of BTEX Concentrations in Indoor Air of Residential Buildings and Atmospheric Ambient Air in Ardabil, Iran. Atmos. Environ. 2016, 132, 91– 97,  DOI: 10.1016/J.ATMOSENV.2016.02.042
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    Preliminary assessment of BTEX concentrations in indoor air of residential buildings and atmospheric ambient air in Ardabil, Iran
    Hazrati, Sadegh; Rostami, Roohollah; Farjaminezhad, Manoochehr; Fazlzadeh, Mehdi
    Atmospheric Environment (2016), 132 (), 91-97CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
    BTEX concns. in indoor and outdoor air of 50 homes were studied in Ardabil city and their influencing parameters including; heating system, using gas stove and samovar, tobacco smoking, the floors in which the monitored homes were located, and kitchen plan were considered in the study. Risk assessment anal. was carried out with the obtained concns. based on EPA IRIS ref. doses. BTEX compds. were sampled by charcoal tubes and the samples were analyzed by a GC-FID. Concns. of benzene (15.18 μg/m3 vs. 8.65 μg/m3), toluene (69.70 μg/m3 vs. 40.56 μg/m3), ethylbenzene (12.07 μg/m3 vs. 4.92 μg/m3) and xylene (48.08 μg/m3 vs. 7.44 μg/m3) in indoor air were significantly (p < 0.05) higher than the levels quantified for outdoor air. The obtained concns. of benzene were considerably higher than the recommended value of 5 μg/m3 established by Iran environmental protection organization. Among the BTEX compds., benzene (HQ = 0.51) and xylene (HQ = 0.47) had notable hazard quotient and were the main pollutants responsible for high hazard index in the monitored homes (HI = 1.003). The results showed considerably high cancer risk for lifetime exposure to the indoor (125 × 10-6) and outdoor (71 × 10-6) benzene. Indoor benzene concns. in homes were significantly influenced by type of heating system, story, and natural gas appliances.
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    Hodshire, A. L.; Carter, E.; Mattila, J. M.; Ilacqua, V.; Zambrana, J.; Abbatt, J. P. D.; Abeleira, A.; Arata, C.; Decarlo, P. F.; Goldstein, A. H.; Ruiz, L. H.; Vance, M. E.; Wang, C.; Farmer, D. K. Detailed Investigation of the Contribution of Gas-Phase Air Contaminants to Exposure Risk during Indoor Activities. Environ. Sci. Technol. 2022, 56, 12148– 12157,  DOI: 10.1021/acs.est.2c01381
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    Detailed investigation of the contribution of gas-phase air contaminants to exposure risk during indoor activities
    Hodshire, Anna L.; Carter, Ellison; Mattila, James M.; Ilacqua, Vito; Zambrana, Jordan; Abbatt, Jonathan P. D.; Abeleira, Andrew; Arata, Caleb; DeCarlo, Peter F.; Goldstein, Allen H.; Ruiz, Lea Hildebrandt; Vance, Marina E.; Wang, Chen; Farmer, Delphine K.
    Environmental Science & Technology (2022), 56 (17), 12148-12157CODEN: ESTHAG; ISSN:1520-5851. (American Chemical Society)
    Anal. capabilities in atm. chem. provide new opportunities to investigate indoor air. HOMEChem was a chem. comprehensive indoor field campaign designed to investigate how common activities, such as cooking and cleaning, impacted indoor air in a test home. We combined gas-phase chem. data of all compds., excluding those with concns. <1 ppt, with established databases of health effect thresholds to evaluate potential risks assocd. with gas-phase air contaminants and indoor activities. The chem. compn. of indoor air is distinct from outdoor air, with gaseous compds. present at higher levels and greater diversity-and thus greater predicted hazard quotients-indoors than outdoors. Common household activities like cooking and cleaning induce rapid changes in indoor air compn., raising levels of multiple compds. with high risk quotients. The HOMEChem data highlight how strongly human activities influence the air we breathe in the built environment, increasing the health risk assocd. with exposure to air contaminants.
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    Yi, H.; Huang, Y.; Tang, X.; Zhao, S.; Xie, X.; Zhang, Y. Characteristics of Non-Methane Hydrocarbons and Benzene Series Emission from Commonly Cooking Oil Fumes. Atmos. Environ. 2019, 200, 208– 220,  DOI: 10.1016/J.ATMOSENV.2018.12.018
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    Characteristics of non-methane hydrocarbons and benzene series emission from commonly cooking oil fumes
    Yi, Honghong; Huang, Yonghai; Tang, Xiaolong; Zhao, Shunzheng; Xie, Xizhou; Zhang, Yuanyuan
    Atmospheric Environment (2019), 200 (), 208-220CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
    Cooking oil fumes is an important source of VOCs pollution in urban area in China. The research of the emission characteristics of NMHC and benzene series which are the representative substances of VOCs in cooking oil fumes was very little. In this study, three kind of most commonly used edible oils (soybean oil, peanut oil and blend oil) were used to generate cooking oil fumes. The concns. of NMHC and benzene series in cooking oil fumes were detected by GC and GC-MS, and were used to calc. the emission factors of these. The concn. of NMHC in soybean oil was significantly higher than that of the other two edible oils so the emission factors were higher than others. The emission polynomials of NMHC and benzene series were obtained by fitting the emission factors. The NMHC emission polynomials are binomial equation and the benzene series emission polynomials are best for trinomial. The emission polynomials of VOCs in cooking oil fumes can not only conveniently and quickly calc. the emissions of the substances but also provide a data basis for subsequent processing.
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    Bhandari, S.; Casillas, G.; Aly, N. A.; Zhu, R.; Newman, G.; Wright, F. A.; Miller, A.; Adler, G.; Rusyn, I.; Chiu, W. A. Spatial and Temporal Analysis of Impacts of Hurricane Florence on Criteria Air Pollutants and Air Toxics in Eastern North Carolina. Int. J. Environ. Res. Public Health 2022, 19, 1757,  DOI: 10.3390/ijerph19031757
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    Spatial and Temporal Analysis of Impacts of Hurricane Florence on Criteria Air Pollutants and Air Toxics in Eastern North Carolina
    Bhandari, Sharmila; Casillas, Gaston; Aly, Noor A.; Zhu, Rui; Newman, Galen; Wright, Fred A.; Miller, Anthony; Adler, Gabriela; Rusyn, Ivan; Chiu, Weihsueh A.
    International Journal of Environmental Research and Public Health (2022), 19 (3), 1757CODEN: IJERGQ; ISSN:1660-4601. (MDPI AG)
    Natural and anthropogenic disasters are assocd. with air quality concerns due to the potential redistribution of pollutants in the environment. Our objective was to conduct a spatiotemporal anal. of air concns. of benzene, toluene, ethylbenzne, and xylene (BTEX) and criteria air pollutants in North Carolina during and after Hurricane Florence. Three sampling campaigns were carried out immediately after the storm (Sept. 2018) and at four-month intervals. BTEX were measured along major roads. Concurrent criteria air pollutant concns. were predicted from modeling. Correlation between air pollutants and possible point sources was conducted using spatial regression. Exceedances of ambient air criteria were obsd. for benzene (in all sampling periods) and PM2.5 (mostly immediately after Florence). For both, there was an assocn. between higher concns. and fueling stations, particularly immediately after Florence. For other pollutants, concns. were generally below levels of regulatory concern. Through characterization of air quality under both disaster and "normal" conditions, this study demonstrates spatial and temporal variation in air pollutants. We found that only benzene and PM2.5 were present at levels of potential concern, and there were localized increases immediately after the hurricane. These substances warrant particular attention in future disaster response research (DR2) investigations.
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    Lebel, E. D.; Michanowicz, D. R.; Bilsback, K. R.; Hill, L. A. L.; Goldman, J. S. W.; Domen, J. K.; Jaeger, J. M.; Ruiz, A.; Shonkoff, S. B. C. Composition, Emissions, and Air Quality Impacts of Hazardous Air Pollutants in Unburned Natural Gas from Residential Stoves in California. Environ. Sci. Technol. 2022, 15828,  DOI: 10.1021/ACS.EST.2C02581
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    Composition, Emissions, and Air Quality Impacts of Hazardous Air Pollutants in Unburned Natural Gas from Residential Stoves in California
    Lebel, Eric D.; Michanowicz, Drew R.; Bilsback, Kelsey R.; Hill, Lee Ann L.; Goldman, Jackson S. W.; Domen, Jeremy K.; Jaeger, Jessie M.; Ruiz, Angelica; Shonkoff, Seth B. C.
    Environmental Science & Technology (2022), 56 (22), 15828-15838CODEN: ESTHAG; ISSN:1520-5851. (American Chemical Society)
    The presence of hazardous air pollutants (HAPs) entrained in end-use natural gas (NG) is an understudied source of human health risks. We performed trace gas analyses on 185 unburned NG samples collected from 159 unique residential NG stoves across seven geog. regions in California. Our analyses commonly detected 12 HAPs with significant variability across region and gas utility. Mean regional benzene, toluene, ethylbenzene, and total xylenes (BTEX) concns. in end-use NG ranged from 1.6-25 ppmv-benzene alone was detected in 99% of samples, and mean concns. ranged from 0.7-12 ppmv (max: 66 ppmv). By applying previously reported NG and methane emission rates throughout California's transmission, storage, and distribution systems, we estd. statewide benzene emissions of 4,200 (95% CI: 1,800-9,700) kg yr-1 that are currently not included in any statewide inventories-equal to the annual benzene emissions from nearly 60,000 light-duty gasoline vehicles. Addnl., we found that NG leakage from stoves and ovens while not in use can result in indoor benzene concns. that can exceed the California Office of Environmental Health Hazard Assessment 8-h Ref. Exposure Level of 0.94 ppbv-benzene concns. comparable to environmental tobacco smoke. This study supports the need to further improve our understanding of leaked downstream NG as a source of health risk.
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    Marrero, J. E.; Townsend-Small, A.; Lyon, D. R.; Tsai, T. R.; Meinardi, S.; Blake, D. R. Estimating Emissions of Toxic Hydrocarbons from Natural Gas Production Sites in the Barnett Shale Region of Northern Texas. Environ. Sci. Technol. 2016, 50, 10756– 10764,  DOI: 10.1021/acs.est.6b02827
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    Estimating Emissions of Toxic Hydrocarbons from Natural Gas Production Sites in the Barnett Shale Region of Northern Texas
    Marrero, Josette E.; Townsend-Small, Amy; Lyon, David R.; Tsai, Tracy R.; Meinardi, Simone; Blake, Donald R.
    Environmental Science & Technology (2016), 50 (19), 10756-10764CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    Oil and natural gas operations continue to expand and move closer to densely populated areas, contributing to growing public concern regarding exposure to hazardous air pollutants. During the Barnett Shale Coordinated Campaign in Oct., 2013, ground-based whole air samples collected downwind from oil and gas sites showed enhancements in several potentially toxic volatile org. compds. vs. background concns. Molar emissions ratios relative to CH4 were detd. for hexane, benzene, toluene, ethylbenzene, and xylene. Using CH4 leak rates measured from the Picarro mobile flux plane system and a Barnett Shale regional CH4 emissions inventory, rates of emission of these toxic gases were calcd. Benzene emissions were 51 ± 4 to 60 ± 4 kg/h; hexane, the most abundantly emitted pollutant, was 642 ± 45 to 1070 ± 340 kg/h. While obsd. hydrocarbon enhancements fell below federal workplace stds., results indicated a possible link between oil and natural gas operation emissions and hazardous air pollutant exposure concerns. Larger public health risks assocd. with natural gas prodn. and distribution were of particular importance and warranted further investigation, particularly since natural gas use increased in the US and internationally.
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    Jo, W. K.; Pack, K. W. Utilization of Breath Analysis for Exposure Estimates of Benzene Associated with Active Smoking. Environ. Res. 2000, 83, 180– 187,  DOI: 10.1006/enrs.2000.4059
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    Utilization of breath analysis for exposure estimates of benzene associated with active smoking
    Jo, Wan-Kuen; Pack, Ku-Won
    Environmental Research (2000), 83 (2), 180-187CODEN: ENVRAL; ISSN:0013-9351. (Academic Press)
    Three different expts. for benzene exposures assocd. with active smoking were carried out. In the first expt., the mean exhaled breath benzene concns. measured 1 min after an active smoke ranged from 58.1-81.3 μg/m3, depending on the com. cigarette brand, while those measured prior to an active smoke ranged from 15.9-19.2 μg/m3. The postexposure breath concns. were much higher than the mean breath concns. reported by some previous studies whose exposure conditions and postsampling times were not controlled. Similar to some previous decay studies conducted for different volatile org. compds. in different microenvironments, the second expt. showed that there was a rapid fall in the breath concn. and thereafter the decrease was much slower. One-compartment half-lives ranged from 30.1-57.8 min. Two-compartment half-lives ranged from 3.2-25.7 min for the first half-life and from 67-462 min for the second half-life. In the final repeated smoke expt. conducted with two specified time intervals, the breath concns. showed increasing trends for both the pre- and the postexposure concns., with few exceptions. However, none of the changes were statistically significant at P<0.05. (c) 2000 Academic Press.
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    Comparison of Bootstrap Confidence Interval Methods for GSCA Using a Monte Carlo Simulation
    Jung Kwanghee; Lee Jaehoon; Gupta Vibhuti; Cho Gyeongcheol
    Frontiers in psychology (2019), 10 (), 2215 ISSN:1664-1078.
    Generalized structured component analysis (GSCA) is a theoretically well-founded approach to component-based structural equation modeling (SEM). This approach utilizes the bootstrap method to estimate the confidence intervals of its parameter estimates without recourse to distributional assumptions, such as multivariate normality. It currently provides the bootstrap percentile confidence intervals only. Recently, the potential usefulness of the bias-corrected and accelerated bootstrap (BCa) confidence intervals (CIs) over the percentile method has attracted attention for another component-based SEM approach-partial least squares path modeling. Thus, in this study, we implemented the BCa CI method into GSCA and conducted a rigorous simulation to evaluate the performance of three bootstrap CI methods, including percentile, BCa, and Student's t methods, in terms of coverage and balance. We found that the percentile method produced CIs closer to the desired level of coverage than the other methods, while the BCa method was less prone to imbalance than the other two methods. Study findings and implications are discussed, as well as limitations and directions for future research.
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    Identifying air pollutants that pose a potential hazard indoors can facilitate exposure mitigation. In this study, we compiled summary results from 77 published studies reporting measurements of chem. pollutants in residences in the United States and in countries with similar lifestyles. These data were used to calc. representative mid-range and upper-bound concns. relevant to chronic exposures for 267 pollutants and representative peak concns. relevant to acute exposures for five activity-assocd. pollutants. Representative concns. are compared to available chronic and acute health stds. for 97 pollutants. Fifteen pollutants appear to exceed chronic health stds. in a large fraction of homes. Nine other pollutants are identified as potential chronic health hazards in a substantial minority of homes, and an addnl. nine are identified as potential hazards in a very small percentage of homes. Nine pollutants are identified as priority hazards based on the robustness of measured concn. data and the fraction of residences that appear to be impacted: acetaldehyde; acrolein; benzene; 1,3-butadiene; 1,4-dichlorobenzene; formaldehyde; naphthalene; nitrogen dioxide; and PM2.5. Activity-based emissions are shown to pose potential acute health hazards for PM2.5, formaldehyde, CO, chloroform, and NO2.
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    Ambient and Emission Trends of Toxic Air Contaminants in California
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    Environmental Science & Technology (2015), 49 (19), 11329-11339CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
    After initiating a toxic air contaminant (TAC) identification and control program in 1984, the California Air Resources Board adopted regulations to reduce TAC emissions from cars, trucks, stationary sources, and consumer products. This work quantifies ambient concn. and emission trends, 1990-2012, for 7 TAC responsible for most known cancer risks assocd. with airborne exposure in California. Of these 7, diesel particulate matter (DPM) is the most important; however, DPM is not directly measured. Based on a novel surrogate method, DPM concns. declined 68%, even though the state population increased 31%, diesel vehicle-miles-traveled increased 81%, and gross state product increased 74%. Based on monitoring data, benzene, 1,3-butadiene, perchloroethylene, and Cr6+ concns. declined 88-94%, and ambient and emissions trends for each of these TAC were similar. These declines generally occurred earlier in California than elsewhere. However, formaldehyde and acetaldehyde, which are photochem. formed in the atm. from volatile org. compds., declined only 20-21%. The collective cancer risk from exposure to these 7 TAC declined 76%. Significant redn. in cancer risk to California residents from air toxics controls implementation, particularly for DPM, is expected to continue.
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  1. Shubham Bansal, Dongning Liu, Qiyue Mao, Nicola Bauer, Binghe Wang. Carbon Monoxide as a Potential Therapeutic Agent: A Molecular Analysis of Its Safety Profiles. Journal of Medicinal Chemistry 2024, 67 (12) , 9789-9815. https://doi.org/10.1021/acs.jmedchem.4c00823
  2. Drew R. Michanowicz, Archana Dayalu, Curtis L. Nordgaard, Jonathan J. Buonocore, Molly W. Fairchild, Robert Ackley, Jessica E. Schiff, Abbie Liu, Nathan G. Phillips, Audrey Schulman, Zeyneb Magavi, John D. Spengler. Rebuttal to the Correspondence on Home is Where the Pipeline Ends: Characterization of Volatile Organic Compounds Present in Natural Gas at the Point of the Residential End User. Environmental Science & Technology 2023, 57 (39) , 14624-14625. https://doi.org/10.1021/acs.est.3c05355
  3. Eric D. Lebel, Drew R. Michanowicz, Kelsey R. Bilsback, Lee Ann L. Hill, Jeremy K. Domen, Jessie M. Jaeger, Seth B. C. Shonkoff. Rebuttal to Correspondence on “Composition, Emissions, and Air Quality Impacts of Hazardous Air Pollutants in Unburned Natural Gas from Residential Stoves in California”. Environmental Science & Technology 2023, 57 (35) , 13090-13091. https://doi.org/10.1021/acs.est.3c04877
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  • Abstract

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    Figure 1

    Figure 1. Mean and median benzene emissions by fuel type (left panels; induction, coil, natural gas, and propane) and emissions from individual cooktop elements and ovens (right panels) in μg C6H6 min–1 by appliance type (gas, coil/radiant, or induction) for burners on high (a,b) or on low (c,d) and for ovens set to 350 °F (e,f). The red points inside the bars in plots a, c, and e are the median values. Bar heights are the mean values, and black error bars are the 95% confidence interval of the mean (calculated as described in methods; see Table S1 for p values). Benzene emission rates were measured directly using the AROMA analyzer (see methods). Burners on “High” in panels a and b refer to the highest-power cooktop element on each stove set to its highest setting; “Low” refers to the lowest-power cooktop element on each stove set to its lowest functional setting. Oven emission rates include the oven preheat and oven cycling (to maintain its temperature) over the 45 m sampling interval. Note the y-axis breaks in panels b, d, and f.

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    Figure 2

    Figure 2. Benzene concentrations in unsealed kitchens as measured immediately after being aired out with outdoor air (mustard circles) and after 45 min with one burner on high or oven set to 350 °F fueled by propane (brown triangles) or gas (orange circles). Each point represents a single measurement; each x-value represents a single kitchen; multiple dots in the same column represent measurements of different burners or ovens in the same kitchen. These measured kitchen concentrations are compared with the upper estimate of benzene concentrations attributable to secondhand tobacco smoke (10) (0.78 ppbv) and the median indoor benzene concentration in the US, Canada, Western Europe, Japan, South Korea, Hong Kong, and Australia derived from a literature survey (47) (0.79 ppbv).

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    Figure 3

    Figure 3. Benzene concentrations (ppbv C6H6) measured in bedrooms furthest from open kitchens with the oven set to 475 °F for 1.5 h and then turned off for 6.5 h. Each point represents a single reading from the AROMA analyzer, and all data points collected are illustrated in the plot. Air-sampling hoses in houses 1, 3, 4, 5, and 6 were placed in bedrooms ∼8 meters down the hall from the kitchen; the sampling hose in house 2 was in a bedroom ∼4 meters down the hall from the kitchen. The solid black line at 1 ppbv benzene represents the California OEHHA 8-h REL for noncancer effects; (8) the solid black line at 8 ppbv benzene represents the California OEEHA acute REL. (8) Several chronic benzene standards are plotted for comparison at the right with dashed black lines for Israel (54) and France (55) at the bottom (0.41 and 0.63 ppbv, respectively), two of the lowest chronic benzene standards globally; the European Union chronic health benchmark (1.56 ppbv), which is the most common chronic health benchmark globally; (9) and, at the top, the chronic standard adopted by the US ATSDR (3.0 ppbv), a department affiliated with the Centers for Disease Control and Prevention. (56) We measured all concentrations in real time using the AROMA VOC analyzer. During the measurements, all interior doors of the houses were open, and no fans were used to mix the air.

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    14. 14
      Friedlingstein, P.; Jones, M. W.; O’Sullivan, M.; Andrew, R. M.; Bakker, D. C. E.; Hauck, J.; Le Quéré, C.; Peters, G. P.; Peters, W.; Pongratz, J.; Sitch, S.; Canadell, J. G.; Ciais, P.; Jackson, R. B.; Alin, S. R.; Anthoni, P.; Bates, N. R.; Becker, M.; Bellouin, N.; Bopp, L.; Chau, T. T. T.; Chevallier, F.; Chini, L. P.; Cronin, M.; Currie, K. I.; Decharme, B.; Djeutchouang, L. M.; Dou, X.; Evans, W.; Feely, R. A.; Feng, L.; Gasser, T.; Gilfillan, D.; Gkritzalis, T.; Grassi, G.; Gregor, L.; Gruber, N.; Gürses, Ö.; Harris, I.; Houghton, R. A.; Hurtt, G. C.; Iida, Y.; Ilyina, T.; Luijkx, I. T.; Jain, A.; Jones, S. D.; Kato, E.; Kennedy, D.; Goldewijk, K. K.; Knauer, J.; Korsbakken, J. I.; Körtzinger, A.; Landschützer, P.; Lauvset, S. K.; Lefèvre, N.; Lienert, S.; Liu, J.; Marland, G.; McGuire, P. C.; Melton, J. R.; Munro, D. R.; Nabel, J. E. M. S.; Nakaoka, S.-I.; Niwa, Y.; Ono, T.; Pierrot, D.; Poulter, B.; Rehder, G.; Resplandy, L.; Robertson, E.; Rödenbeck, C.; Rosan, T. M.; Schwinger, J.; Schwingshackl, C.; Séférian, R.; Sutton, A. J.; Sweeney, C.; Tanhua, T.; Tans, P. P.; Tian, H.; Tilbrook, B.; Tubiello, F.; van der Werf, G. R.; Vuichard, N.; Wada, C.; Wanninkhof, R.; Watson, A. J.; Willis, D.; Wiltshire, A. J.; Yuan, W.; Yue, C.; Yue, X.; Zaehle, S.; Zeng, J. Global Carbon Budget 2021. Earth Syst. Sci. Data 2022, 14, 1917– 2005,  DOI: 10.5194/essd-14-1917-2022
      There is no corresponding record for this reference.
    15. 15
      Lebel, E. D.; Lu, H. S.; Speizer, S. A.; Finnegan, C. J.; Jackson, R. B. Quantifying Methane Emissions from Natural Gas Water Heaters. Environ. Sci. Technol. 2020, 54, 5737– 5745,  DOI: 10.1021/acs.est.9b07189
      20
      Quantifying Methane Emissions from Natural Gas Water Heaters
      Lebel, Eric D.; Lu, Harmony S.; Speizer, Simone A.; Finnegan, Colin J.; Jackson, Robert B.
      Environmental Science & Technology (2020), 54 (9), 5737-5745CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Natural gas appliance CH4 emissions are the least characterized portion of the fossil fuel supply chain. This work examd. water heaters from 64 northern California homes to: quantify CH4 emissions from natural gas leaks and incomplete combustion while heater is off, turning on/off, and in steady-state operation from 35 homes; and characterizing daily use patterns over ∼1-2 mo/water heater to est. activity factors from 46 homes. On av., individual tank-less water heaters emitted 2390 (95% confidence interval [CI]: 2250, 2540) g CH4/yr; 0.93% [0.87%, 0.99%] of their natural gas consumed was primarily from on/off pulses. On av., storage water heaters emitted 1400 [1240, 1560] g CH4/yr; 0.39% [0.34%, 0.43%] of their natural gas consumption. Despite higher CH4 emissions, tank-less water heaters generated 29% less CO2e20 than storage water heaters because they used less energy to heat a unit of water. Scaling these measured emissions by no. of storage and tank-less water heaters in the US (56.8 and 1.2 million, resp.), overall, water heaters emitted an estd. 82.3 [73.2, 91.5] Gg CH4/yr, 0.40% [0.35%, 0.44%] of all natural gas consumed by these appliances which is comparable in percentage to USEPA estd. CH4 emissions from upstream natural gas prodn.
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    16. 16
      Merrin, Z.; Francisco, P. W. Unburned Methane Emissions from Residential Natural Gas Appliances. Environ. Sci. Technol. 2019, 53, 5473– 5482,  DOI: 10.1021/acs.est.8b05323
      21
      Unburned Methane Emissions from Residential Natural Gas Appliances
      Merrin, Zachary; Francisco, Paul W.
      Environmental Science & Technology (2019), 53 (9), 5473-5482CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      CH4, the primary natural gas (NG) component, is a potent greenhouse gas. NG is a common fuel for residential appliances due to low cost, high energy d., and relatively clean combustion. NG combustion gas contains unburned CH4 due to inevitable incomplete combustion. A field campaign measuring CH4 concns. in residential NG appliance exhaust gas was conducted in Boston and Indianapolis to det. its contribution to overall emissions. NG space heating, water heating, and cooking appliances were measured in 100 homes. Appliance exhaust typically exhibited a brief CH4 concn. spike during ignition and extinguishment, and relatively low concns. during steady-state operation. Exceptions to this pattern include ovens, sub-optimal stove burners, and tank-less water heaters, which have a different operating pattern or non-trivial steady-state concns. Results were combined with appliance use and prevalence assumptions to est. total emissions. Annually, ∼30 [97.5% confidence interval [CI]: 19-160] Gg CH4 emissions can be attributed to US residential NG appliances, corresponding to ∼830 [530-4500] Gg CO2 equiv. (CO2e100). This accounts for ∼0.1% [0.08-0.7%] of US anthropogenic CH4 emissions (which account for ∼10% of total US greenhouse gas emissions) and corresponds to an emission factor of 0.38 g/kg NG consumed (0.038% [0.024-0.21%]).
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    17. 17
      Fischer, M. L.; Chan, W. R.; Delp, W.; Jeong, S.; Rapp, V.; Zhu, Z. An Estimate of Natural Gas Methane Emissions from California Homes. Environ. Sci. Technol. 2018, 52, 10205– 10213,  DOI: 10.1021/acs.est.8b03217
      22
      An Estimate of Natural Gas Methane Emissions from California Homes
      Fischer, Marc L.; Chan, Wanyu R.; Delp, Woody; Jeong, Seongeun; Rapp, Vi; Zhu, Zhimin
      Environmental Science & Technology (2018), 52 (17), 10205-10213CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Post-meter CH4 emissions from the California residential natural gas (NG) system were estd. using measurements and anal. from a sample of homes and appliances. Quiescent, whole-house emissions (i.e., pipe leaks, pilot lights) were measured with a mass balance method in 75 California homes; CH4:CO2 emission ratios were measured for steady operation of individual combustion appliances and, sep., for transient operation of three tank-less water heaters. Measured, quiescent whole-house emissions were typically <1 g CH4/day, though they exhibited long-tailed gamma distributions with values >10 g CH4/day. Most operating appliances yielded undetectable CH4:CO2 enhancements in steady operation (<0.01% of gas consumed), though storage water heaters and stove-tops exhibited long-tailed gamma distributions contg. high values (∼1-3% of gas consumed), and transients were obsd. for tank-less heaters. Extrapolating results to a state-level using Bayesian Markov chain Monte Carlo sampling in conjunction with California housing statistics and gas use information suggested quiescent house leakage of 23.4 (13.7-45.6, at 95% confidence) Gg CH4, with pilot lights contributing ∼30%. Appliance steady state operating emissions and their pilot lights were 13.3 (6.6-37.1) Gg CH4/yr, an order of magnitude larger than current inventory ests., with transients likely further increasing appliance emissions. Together, residential NG emissions were 35.7 (21.7-64.0) Gg CH4/yr, equiv. to ∼15% of the state NG CH4 emissions, suggesting leak repair, improved combustion appliances, and adoption of non-fossil energy heating sources can help California meet its 2050 climate goals.
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    18. 18
      World Health Organization Global Air Quality Guidelines: Particulate Matter (PM2.5 and PM10), Ozone, Nitrogen Dioxide, Sulfur Dioxide and Carbon Monoxide ; 2021. (accessed 2022-07-11).
      There is no corresponding record for this reference.
    19. 19
      US Environmental Protection Agency Review of the Primary National Ambient Air Quality Standards for Oxides of Nitrogen ; 2018. . (accessed 2022-07-11).
      There is no corresponding record for this reference.
    20. 20
      Lin, W.; Brunekreef, B.; Gehring, U. Meta-Analysis of the Effects of Indoor Nitrogen Dioxide and Gas Cooking on Asthma and Wheeze in Children. Int. J. Epidemiol. 2013, 42, 1724– 1737,  DOI: 10.1093/IJE/DYT150
      25
      Meta-analysis of the effects of indoor nitrogen dioxide and gas cooking on asthma and wheeze in children
      Lin Weiwei; Brunekreef Bert; Gehring Ulrike
      International journal of epidemiology (2013), 42 (6), 1724-37 ISSN:.
      BACKGROUND: Since the meta-analysis on the association between indoor nitrogen dioxide (NO2) and childhood respiratory illness in 1992, many new studies have been published. The quantitative effects of indoor NO2 on respiratory illness have not been estimated in a formal meta-analysis since then. We aimed to quantify the association of indoor NO2 and its main source (gas cooking) with childhood asthma and wheeze. METHODS: We extracted the association between indoor NO2 (and gas cooking) and childhood asthma and wheeze from population studies published up to 31 March 2013. Data were analysed by inverse-variance-weighted, random-effects meta-analysis. Sensitivity analyses were conducted for different strata. Publication bias and heterogeneity between studies were investigated. RESULTS: A total of 41 studies met the inclusion criteria. The summary odds ratio from random effects meta-analysis for asthma and gas cooking exposure was 1.32 [95% confidential interval (CI) 1.18-1.48], and for a 15-ppb increase in NO2 it was 1.09 (95% CI 0.91-1.31). Indoor NO2 was associated with current wheeze (random effects OR 1.15; 95% CI 1.06-1.25). The estimates did not vary much with age or between regions. There was no evidence of publication bias. CONCLUSIONS: This meta-analysis provides quantitative evidence that, in children, gas cooking increases the risk of asthma and indoor NO2 increases the risk of current wheeze.
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    21. 21
      Gruenwald, T.; Seals, B. A.; Knibbs, L. D.; Hosgood, H. D., III Population Attributable Fraction of Gas Stoves and Childhood Asthma in the United States. Int. J. Environ. Res. Public Health 2023, 20, 75,  DOI: 10.3390/IJERPH20010075
      There is no corresponding record for this reference.
    22. 22
      World Health Organization Regional Office for Europe Guidelines for Indoor Air Quality, Selected Pollutants ; 2010. (accessed 2022-06-15).
      There is no corresponding record for this reference.
    23. 23
      US Environmental Protection Agency Benzene Chronic Health Hazard Assessments ; 2003. (accessed 2022-10-05).
      There is no corresponding record for this reference.
    24. 24
      Jin, H.; Frassoldati, A.; Wang, Y.; Zhang, X.; Zeng, M.; Li, Y.; Qi, F.; Cuoci, A.; Faravelli, T. Kinetic Modeling Study of Benzene and PAH Formation in Laminar Methane Flames. Combust. Flame 2015, 162, 1692– 1711,  DOI: 10.1016/j.combustflame.2014.11.031
      29
      Kinetic modeling study of benzene and PAH formation in laminar methane flames
      Jin, Hanfeng; Frassoldati, Alessio; Wang, Yizun; Zhang, Xiaoyuan; Zeng, Meirong; Li, Yuyang; Qi, Fei; Cuoci, Alberto; Faravelli, Tiziano
      Combustion and Flame (2015), 162 (5), 1692-1711CODEN: CBFMAO; ISSN:0010-2180. (Elsevier B.V.)
      Methane is probably the most frequently studied hydrocarbon fuel. Both its oxidn. mechanism and its pyrolysis to higher-mass products have received considerable attention. In order to have a glance into the combustion chem. of methane, a detailed kinetic model was developed to reproduce the fuel decompn. and the formation of benzene and PAHs in laminar methane flames. The model was validated against the exptl. data from previous works on premixed flames, counter flow diffusion flames, and finally the coflow diffusion flames exptl. investigated in this work. Reaction pathway anal. highlights the combustion kinetics of methane in various flame conditions, including the differences in fuel consumption paths, and the formation of low mol. wt. species, benzene and PAHs. C2-C4 species are important intermediates in the combustion of methane, which significantly control the formation of larger mols. and the emission of pollutants. Resonantly stabilized free radicals, such as propargyl, benzyl and indenyl radicals are major PAH precursors, but other arom. radicals like Ph and naphthyl radicals also play a significant role. Their self-recombination reactions or the addn. reactions on small hydrocarbon intermediates (e.g., C2 species) are effective arom. grown pathways in laminar methane flames.
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    25. 25
      Senkan, S. Formation of Polycyclic Aromatic Hydrocarbons (PAH) in Methane Combustion: Comparative New Results from Premixed Flames. Combust. Flame 1996, 107, 141– 150,  DOI: 10.1016/0010-2180(96)00044-2
      30
      Formation of polycyclic aromatic hydrocarbons (PAH) in methane combustion: comparative new results from premixed flames
      Senkan, Selim; Castaldi, Marco
      Combustion and Flame (1996), 107 (1/2), 141-150CODEN: CBFMAO; ISSN:0010-2180. (Elsevier)
      Direct sampling and gas chromatog.-mass spectral anal. of fuel-rich, laminar, premixed flames of CH4 indicated the prodn. of higher in-flame peak concns. of benzene and polycyclic arom. hydrocarbons (PAH) than in the flames of ethane under similar combustion conditions. These findings were surprising and significant because the methane flame not only has a higher H/C ratio and lower carbon d., but also contained an odd no. of carbon atoms, and produced the least amt. of acetylene. These findings had implications in PAH formation as well as in soot surface reactions in hydrocarbon flames. C4H2 and C3H4 species were implicated as intermediates in benzene formation.
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    26. 26
      Cuoci, A.; Frassoldati, A.; Faravelli, T.; Jin, H.; Wang, Y.; Zhang, K.; Glarborg, P.; Qi, F. Experimental and Detailed Kinetic Modeling Study of PAH Formation in Laminar Co-Flow Methane Diffusion Flames. Proc. Combust. Inst. 2013, 34, 1811– 1818,  DOI: 10.1016/j.proci.2012.05.085
      31
      Experimental and detailed kinetic modeling study of PAH formation in laminar co-flow methane diffusion flames
      Cuoci, Alberto; Frassoldati, Alessio; Faravelli, Tiziano; Jin, Hanfeng; Wang, Yizun; Zhang, Kuiwen; Glarborg, Peter; Qi, Fei
      Proceedings of the Combustion Institute (2013), 34 (1), 1811-1818CODEN: PCIRC2; ISSN:1540-7489. (Elsevier B.V.)
      In the present paper, synchrotron VUV photoionization mass spectrometry is used to study the detailed chem. of co-flow methane diffusion flames with different diln. ratios. The exptl. results constitute a comprehensive characterization of species important for PAH and soot formation under conditions that resemble those of practical flames. In addn. to the main C1/C2 species, unsatd. C3 (C3H2, C3H3, aC3H4, pC3H4), C4 (C4H2, C4H4, C4H6), and C6 (C6H2) species as well as first aroms. (C6H6, C7H8, C10H8, C12H8) are detected. The laminar, co-flow flames were simulated using an original CFD code based on the operator-splitting technique, specifically conceived to handle large kinetic mechanisms. The detailed kinetic modeling was effectively used to describe and analyze the fuel consumption and the formation of PAH. Exptl. measurements and numerical predictions were found to be in satisfactory agreement and showed the relative importance of the C2 and C3 mechanisms in the formation of the first aroms.
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    27. 27
      Georganta, E.; Rahman, R. K.; Raj, A.; Sinha, S. Growth of Polycyclic Aromatic Hydrocarbons (PAHs) by Methyl Radicals: Pyrene Formation from Phenanthrene. Combust. Flame 2017, 185, 129– 141,  DOI: 10.1016/j.combustflame.2017.07.011
      32
      Growth of polycyclic aromatic hydrocarbons (PAHs) by methyl radicals: Pyrene formation from phenanthrene
      Georganta, Evgenia; Rahman, Ramees K.; Raj, Abhijeet; Sinha, Sourab
      Combustion and Flame (2017), 185 (), 129-141CODEN: CBFMAO; ISSN:0010-2180. (Elsevier B.V.)
      The formation of polycyclic arom. hydrocarbons (PAHs) in high temp. environments is an ongoing area of research due to the mismatch between the exptl. and simulated concn. profiles of PAHs in several flames. In this work, the role of Me radicals in the growth of PAHs is identified by developing a detailed reaction mechanism for the conversion of phenanthrene to pyrene by Me radicals. The reaction energetics are obtained through quantum calcns. using B3LYP and M06-2X functionals along with 6-311++G(d,p) basis set, and are used to compare the competing channels for pyrene formation. The transition state theory is used to det. the reaction kinetics. Through kinetic simulations, the most preferred path for pyrene formation from phenanthrene is detd. To quantify the contribution of the newly found reactions in PAH growth in the presence of other competing PAH mechanisms, the reactions are merged with a recently developed and well-validated mechanism for C1-C4 hydrocarbons with detailed PAH chem. Three premixed laminar aliph. flames were simulated with the updated mechanism. It was obsd. that the new reactions did not appreciably influence the computed profiles of phenanthrene and pyrene. Through the rate-of-prodn. anal., it was found that the phenanthrene radicals created through H-abstraction were more susceptible to attack by C2H2 than by Me radicals. The indirect role of Me radicals in PAH formation and growth is shown.
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    28. 28
      Anosike, C. R. Unhealthy Effects of Gas Flaring and Wayforward to Actualize the Stopping of Gas Flaring in Nigeria. Society of Petroleum Engineers - Nigeria Annual International Conference and Exhibition 2010, NAICE; SPE, 2010, 1, 199– 202.  DOI: 10.2118/136970-MS .
      There is no corresponding record for this reference.
    29. 29
      US Environmental Protection Agency Emission Factor Documentation for AP-42 Section 1.4 Natural Gas Combustion ; 1998. (accessed 2022-10-23).
      There is no corresponding record for this reference.
    30. 30
      Zhang, J.; Smith, K. R. Hydrocarbon Emissions and Health Risks from Cookstoves in Developing Countries. J. Exposure Anal. Environ. Epidemiol. 1996, 6, 147– 161
      35
      Hydrocarbon emissions and health risks from cookstoves in developing countries
      Zhang, Junfeng; Smith, Kirk R.
      Journal of Exposure Analysis and Environmental Epidemiology (1996), 6 (2), 147-161CODEN: JEAEE9; ISSN:1053-4245. (Princeton Scientific)
      Nonmethane hydrocarbon emissions from several types of cookstoves commonly used in developing countries were measured in a pilot study conducted in Manila, the Philippines. Wood, charcoal, kerosene, and liquefied petroleum gas (LPG) were tested. Because kerosene was burned in 3 different types of stoves, there were 6 fuel/stove combinations tested. Fifty-nine nonmethane hydrocarbons were identified frequently in emissions of these cookstoves, with emission ratios to CO2 ≤5.3 × 10-3. The emissions were quantitated with emission factors on both a mass basis (emissions/kg fuel) and a task basis (emissions/cooking task). On a task basis, combustion of biomass fuels (wood and charcoal) generally produced higher emission factors than combustion of fossil fuels (kerosene and LPG). One type of kerosene stove (wick stove), however, still generated the greatest emissions of some individual and classes of hydrocarbons, indicating that emissions were dependent on not only fuel types but also combustion devices. Some hydrocarbons, e.g., benzene, 1,3-butadiene, styrene, and xylenes, were of concern because of their carcinogenic properties. The lifetime risk from exposures to these compds. emitted from cookstoves was tentatively estd. using a simple exposure model and published cancer potencies.
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    31. 31
      Lan, Q.; Zhang, L.; Li, G.; Vermeulen, R.; Weinberg, R. S.; Dosemeci, M.; Rappaport, S. M.; Shen, M.; Alter, B. P.; Wu, Y.; Kopp, W.; Waidyanatha, S.; Rabkin, C.; Guo, W.; Chanock, S.; Hayes, R. B.; Linet, M.; Kim, S.; Yin, S.; Rothman, N.; Smith, M. T. Hematotoxicity in Workers Exposed to Low Levels of Benzene. Science (1979) 2004, 306, 1774– 1776,  DOI: 10.1126/science.1102443
      There is no corresponding record for this reference.
    32. 32
      Snyder, R. Leukemia and Benzene. Int. J. Environ. Res. Public Health 2012, 9, 2875– 2893,  DOI: 10.3390/IJERPH9082875
      37
      Leukemia and benzene
      Snyder, Robert
      International Journal of Environmental Research and Public Health (2012), 9 (), 2875-2893CODEN: IJERGQ; ISSN:1660-4601. (MDPI AG)
      A review. Excessive exposure to benzene has been known for more than a century to damage the bone marrow resulting in decreases in the nos. of circulating blood cells, and ultimately, aplastic anemia. Of more recent vintage has been the appreciation that an alternative outcome of benzene exposure has been the development of one or more types of leukemia. While many investigators agree that the array of toxic metabolites, generated in the liver or in the bone marrow, can lead to traumatic bone marrow injury, the more subtle mechanisms leading to leukemia have yet to be critically dissected. This problem appears to have more general interest because of the recognition that so-called "second cancer" that results from prior treatment with alkylating agents to yield tumor remissions, often results in a type of leukemia reminiscent of benzene-induced leukemia. Furthermore, there is a growing literature attempting to characterize the fine structure of the marrow and the identification of so called "niches" that house a variety of stem cells and other types of cells. Some of these "niches" may harbor cells capable of initiating leukemias. The control of stem cell differentiation and proliferation via both inter- and intra-cellular signaling will ultimately det. the fate of these transformed stem cells. The ability of these cells to avoid checkpoints that would prevent them from contributing to the leukemogenic response is an addnl. area for study. Much of the study of benzene-induced bone marrow damage has concd. on detg. which of the benzene metabolites lead to leukemogenesis. The emphasis now should be directed to understanding how benzene metabolites alter bone marrow cell biol.
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    33. 33
      Singer, B. C.; Hodgson, A. T.; Nazaroff, W. W. Gas-Phase Organics in Environmental Tobacco Smoke: 2. Exposure-Relevant Emission Factors and Indirect Exposures from Habitual Smoking. Atmos. Environ. 2003, 37, 5551– 5561,  DOI: 10.1016/J.ATMOSENV.2003.07.015
      38
      Gas-phase organics in environmental tobacco smoke: 2. Exposure-relevant emission factors and indirect exposures from habitual smoking
      Singer, Brett C.; Hodgson, Alfred T.; Nazaroff, William W.
      Atmospheric Environment (2003), 37 (39-40), 5551-5561CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Science B.V.)
      Sorption of emitted gas-phase org. compds. onto material surfaces affects environmental tobacco smoke (ETS) compn. and exposures indoors. We have introduced a new metric, the exposure relevant emission factor (EREF) that accounts for sorptive uptake and reemission to give the mass of individual ETS constituents available for exposure over a day in which smoking occurs. This paper describes month-long expts. to investigate sorption effects on EREFs and potential ETS exposures under habitual smoking conditions. Cigarettes were smoked in a 50-m3 furnished room over a 3-h period 6-7 days per wk, with continuous ventilation at 0.3, 0.6, or 2.1 h-1. Org. gas concns. were measured every few days over 4-h "smoking", 10-h "post-smoking" and 10-h "background" periods. Concn. patterns of volatile ETS components including 1,3-butadiene, benzene and acrolein were similar to those calcd. for a theor. non-sorbing tracer, indicating limited sorption. Concns. of ETS tracers, e.g. 3-ethenylpyridine (3-EP) and nicotine, and lower volatility toxic air contaminants including phenol, cresols, and naphthalene increased as expts. progressed, indicating mass accumulation on surfaces and higher desorption rates. Daily patterns stabilized after week 2, yielding a steady daily cycle of ETS concns. assocd. with habitual smoking. EREFs for sorbing compds. were higher under steady cycle vs. single-day smoking conditions by ∼50% for 3-EP, and by 2-3 times for nicotine, phenol, cresols, naphthalene, and methylnaphthalenes. Our results provide relevant information about potential indirect exposures from residual ETS (non-smoker enters room shortly after smoker finishes) and from reemission, and their importance relative to direct exposures (non-smoker present during smoking). Under the conditions examd., indirect exposures accounted for a larger fraction of total potential exposures for sorbing vs. non-sorbing compds., and at lower vs. higher ventilation rates. Increasing ventilation can reduce indirect exposures to very low levels for non-sorbing ETS components, but indirect routes accounted for ∼50% of potential nicotine exposures during non-smoking periods at all ventilation rates.
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    34. 34
      Ferrero, A.; Esplugues, A.; Estarlich, M.; Llop, S.; Cases, A.; Mantilla, E.; Ballester, F.; Iñiguez, C. Infants’ Indoor and Outdoor Residential Exposure to Benzene and Respiratory Health in a Spanish Cohort. Environ. Pollut. 2017, 222, 486– 494,  DOI: 10.1016/j.envpol.2016.11.065
      39
      Infants' indoor and outdoor residential exposure to benzene and respiratory health in a Spanish cohort
      Ferrero, Amparo; Esplugues, Ana; Estarlich, Marisa; Llop, Sabrina; Cases, Amparo; Mantilla, Enrique; Ballester, Ferran; Iniguez, Carmen
      Environmental Pollution (Oxford, United Kingdom) (2017), 222 (), 486-494CODEN: ENPOEK; ISSN:0269-7491. (Elsevier Ltd.)
      Benzene exposure represents a potential risk for children's health. Apart from being a known carcinogen for humans (group 1 according to IARC), there is scientific evidence suggesting a relationship between benzene exposure and respiratory problems in children. But results are still inconclusive and inconsistent. This study aims to assess the determinants of exposure to indoor and outdoor residential benzene levels and its relationship with respiratory health in infants. Participants were 1-yr-old infants (N = 352) from the INMA cohort from Valencia (Spain). Residential benzene exposure levels were measured inside and outside dwellings by means of passive samplers in a 15-day campaign. Persistent cough, low respiratory tract infections and wheezing during the first year of life, and covariates (dwelling traits, lifestyle factors and sociodemog. data) were obtained from parental questionnaires. Multiple Tobit regression and logistic regression models were performed to assess factors assocd. to residential exposure levels and health assocns., resp. Indoor levels were higher than outdoor ones (1.46 and 0.77 μg/m3, resp.; p < 0.01). A considerable percentage of dwellings, 42% and 21% indoors and outdoors resp., surpassed the WHO guideline of 1.7 μg/m3 derived from a lifetime risk of leukemia above 1/100 000. Monitoring season, maternal country of birth and parental tobacco consumption were assocd. with residential benzene exposure (indoor and outdoors). Addnl., indoor levels were assocd. with mother's age and type of heating, and outdoor levels were linked with zone of residence and distance from industrial areas. After adjustment for confounding factors, no significant assocns. were found between residential benzene exposure levels and respiratory health in infants. Hence, our study did not support the hypothesis for the benzene exposure effect on respiratory health in children. Even so, it highlights a public health concern related to the personal exposure levels, since a considerable no. of children surpassed the abovementioned WHO guideline for benzene exposure.
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    35. 35
      Begou, P.; Kassomenos, P. One-Year Measurements of Toxic Benzene Concentrations in the Ambient Air of Greece: An Estimation of Public Health Risk. Atmos. Pollut. Res. 2020, 11, 1829– 1838,  DOI: 10.1016/J.APR.2020.07.011
      40
      One-year measurements of toxic benzene concentrations in the ambient air of Greece: An estimation of public health risk
      Begou, Paraskevi; Kassomenos, Pavlos
      Atmospheric Pollution Research (2020), 11 (10), 1829-1838CODEN: APRTCD; ISSN:1309-1042. (Elsevier B.V.)
      In this study, the ambient benzene concns. were measured in 7 air quality monitoring stations in Greece. The pollutant measurements were continuously being collected from the air quality monitoring network of the country through a calendar year (from 1st Jan. 2016 to 31st Dec. 2016). The monitoring stations were classified as Urban Traffic, Urban-Industrial, Suburban-Industrial and Urban Background according to the regional type zone. The highest ambient benzene concns. were measured during the winter period while the lowest ones were measured during the summer months. The annual mean values of benzene concns. varied between 0.81 ± 0.56μg/m3 (in Elefsina station) and 5.63 ± 3.68μg/m3 (in Patission station) across the air quality monitoring stations under study. In addn., a health risk assessment was carried out in order to det. the effects of ambient benzene on the population health in Greece, considering both cancer and non-cancer effects. We calcd. the Integrated Lifetime Cancer Risk (ILTCR) assocd. with the inhalation exposure to ambient benzene. Regarding the non-cancer effects, we estd. the Hazard Quotient (HQ) values. Moreover, the quantification of the Environmental Burden of Disease (EBD), due to the exposure to ambient benzene was calcd. considering 4 exposure scenarios. These scenarios were based on the annual benzene concns. detected in the country. Our anal. revealed that the exposure to ambient benzene in Greece causes an amt. of annual Disability-Adjusted Life Years (DALYs) which varied between 0.262 and 0.655 DALYs lost per 100,000 inhabitants.
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    36. 36
      Hazrati, S.; Rostami, R.; Farjaminezhad, M.; Fazlzadeh, M. Preliminary Assessment of BTEX Concentrations in Indoor Air of Residential Buildings and Atmospheric Ambient Air in Ardabil, Iran. Atmos. Environ. 2016, 132, 91– 97,  DOI: 10.1016/J.ATMOSENV.2016.02.042
      41
      Preliminary assessment of BTEX concentrations in indoor air of residential buildings and atmospheric ambient air in Ardabil, Iran
      Hazrati, Sadegh; Rostami, Roohollah; Farjaminezhad, Manoochehr; Fazlzadeh, Mehdi
      Atmospheric Environment (2016), 132 (), 91-97CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
      BTEX concns. in indoor and outdoor air of 50 homes were studied in Ardabil city and their influencing parameters including; heating system, using gas stove and samovar, tobacco smoking, the floors in which the monitored homes were located, and kitchen plan were considered in the study. Risk assessment anal. was carried out with the obtained concns. based on EPA IRIS ref. doses. BTEX compds. were sampled by charcoal tubes and the samples were analyzed by a GC-FID. Concns. of benzene (15.18 μg/m3 vs. 8.65 μg/m3), toluene (69.70 μg/m3 vs. 40.56 μg/m3), ethylbenzene (12.07 μg/m3 vs. 4.92 μg/m3) and xylene (48.08 μg/m3 vs. 7.44 μg/m3) in indoor air were significantly (p < 0.05) higher than the levels quantified for outdoor air. The obtained concns. of benzene were considerably higher than the recommended value of 5 μg/m3 established by Iran environmental protection organization. Among the BTEX compds., benzene (HQ = 0.51) and xylene (HQ = 0.47) had notable hazard quotient and were the main pollutants responsible for high hazard index in the monitored homes (HI = 1.003). The results showed considerably high cancer risk for lifetime exposure to the indoor (125 × 10-6) and outdoor (71 × 10-6) benzene. Indoor benzene concns. in homes were significantly influenced by type of heating system, story, and natural gas appliances.
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    37. 37
      Hodshire, A. L.; Carter, E.; Mattila, J. M.; Ilacqua, V.; Zambrana, J.; Abbatt, J. P. D.; Abeleira, A.; Arata, C.; Decarlo, P. F.; Goldstein, A. H.; Ruiz, L. H.; Vance, M. E.; Wang, C.; Farmer, D. K. Detailed Investigation of the Contribution of Gas-Phase Air Contaminants to Exposure Risk during Indoor Activities. Environ. Sci. Technol. 2022, 56, 12148– 12157,  DOI: 10.1021/acs.est.2c01381
      42
      Detailed investigation of the contribution of gas-phase air contaminants to exposure risk during indoor activities
      Hodshire, Anna L.; Carter, Ellison; Mattila, James M.; Ilacqua, Vito; Zambrana, Jordan; Abbatt, Jonathan P. D.; Abeleira, Andrew; Arata, Caleb; DeCarlo, Peter F.; Goldstein, Allen H.; Ruiz, Lea Hildebrandt; Vance, Marina E.; Wang, Chen; Farmer, Delphine K.
      Environmental Science & Technology (2022), 56 (17), 12148-12157CODEN: ESTHAG; ISSN:1520-5851. (American Chemical Society)
      Anal. capabilities in atm. chem. provide new opportunities to investigate indoor air. HOMEChem was a chem. comprehensive indoor field campaign designed to investigate how common activities, such as cooking and cleaning, impacted indoor air in a test home. We combined gas-phase chem. data of all compds., excluding those with concns. <1 ppt, with established databases of health effect thresholds to evaluate potential risks assocd. with gas-phase air contaminants and indoor activities. The chem. compn. of indoor air is distinct from outdoor air, with gaseous compds. present at higher levels and greater diversity-and thus greater predicted hazard quotients-indoors than outdoors. Common household activities like cooking and cleaning induce rapid changes in indoor air compn., raising levels of multiple compds. with high risk quotients. The HOMEChem data highlight how strongly human activities influence the air we breathe in the built environment, increasing the health risk assocd. with exposure to air contaminants.
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    38. 38
      How to deep-fry safely | BBC Good Food; (accessed 2023-01-19).
      There is no corresponding record for this reference.
    39. 39
      Yi, H.; Huang, Y.; Tang, X.; Zhao, S.; Xie, X.; Zhang, Y. Characteristics of Non-Methane Hydrocarbons and Benzene Series Emission from Commonly Cooking Oil Fumes. Atmos. Environ. 2019, 200, 208– 220,  DOI: 10.1016/J.ATMOSENV.2018.12.018
      44
      Characteristics of non-methane hydrocarbons and benzene series emission from commonly cooking oil fumes
      Yi, Honghong; Huang, Yonghai; Tang, Xiaolong; Zhao, Shunzheng; Xie, Xizhou; Zhang, Yuanyuan
      Atmospheric Environment (2019), 200 (), 208-220CODEN: AENVEQ; ISSN:1352-2310. (Elsevier Ltd.)
      Cooking oil fumes is an important source of VOCs pollution in urban area in China. The research of the emission characteristics of NMHC and benzene series which are the representative substances of VOCs in cooking oil fumes was very little. In this study, three kind of most commonly used edible oils (soybean oil, peanut oil and blend oil) were used to generate cooking oil fumes. The concns. of NMHC and benzene series in cooking oil fumes were detected by GC and GC-MS, and were used to calc. the emission factors of these. The concn. of NMHC in soybean oil was significantly higher than that of the other two edible oils so the emission factors were higher than others. The emission polynomials of NMHC and benzene series were obtained by fitting the emission factors. The NMHC emission polynomials are binomial equation and the benzene series emission polynomials are best for trinomial. The emission polynomials of VOCs in cooking oil fumes can not only conveniently and quickly calc. the emissions of the substances but also provide a data basis for subsequent processing.
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    40. 40
      Bhandari, S.; Casillas, G.; Aly, N. A.; Zhu, R.; Newman, G.; Wright, F. A.; Miller, A.; Adler, G.; Rusyn, I.; Chiu, W. A. Spatial and Temporal Analysis of Impacts of Hurricane Florence on Criteria Air Pollutants and Air Toxics in Eastern North Carolina. Int. J. Environ. Res. Public Health 2022, 19, 1757,  DOI: 10.3390/ijerph19031757
      45
      Spatial and Temporal Analysis of Impacts of Hurricane Florence on Criteria Air Pollutants and Air Toxics in Eastern North Carolina
      Bhandari, Sharmila; Casillas, Gaston; Aly, Noor A.; Zhu, Rui; Newman, Galen; Wright, Fred A.; Miller, Anthony; Adler, Gabriela; Rusyn, Ivan; Chiu, Weihsueh A.
      International Journal of Environmental Research and Public Health (2022), 19 (3), 1757CODEN: IJERGQ; ISSN:1660-4601. (MDPI AG)
      Natural and anthropogenic disasters are assocd. with air quality concerns due to the potential redistribution of pollutants in the environment. Our objective was to conduct a spatiotemporal anal. of air concns. of benzene, toluene, ethylbenzne, and xylene (BTEX) and criteria air pollutants in North Carolina during and after Hurricane Florence. Three sampling campaigns were carried out immediately after the storm (Sept. 2018) and at four-month intervals. BTEX were measured along major roads. Concurrent criteria air pollutant concns. were predicted from modeling. Correlation between air pollutants and possible point sources was conducted using spatial regression. Exceedances of ambient air criteria were obsd. for benzene (in all sampling periods) and PM2.5 (mostly immediately after Florence). For both, there was an assocn. between higher concns. and fueling stations, particularly immediately after Florence. For other pollutants, concns. were generally below levels of regulatory concern. Through characterization of air quality under both disaster and "normal" conditions, this study demonstrates spatial and temporal variation in air pollutants. We found that only benzene and PM2.5 were present at levels of potential concern, and there were localized increases immediately after the hurricane. These substances warrant particular attention in future disaster response research (DR2) investigations.
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    41. 41
      Lebel, E. D.; Michanowicz, D. R.; Bilsback, K. R.; Hill, L. A. L.; Goldman, J. S. W.; Domen, J. K.; Jaeger, J. M.; Ruiz, A.; Shonkoff, S. B. C. Composition, Emissions, and Air Quality Impacts of Hazardous Air Pollutants in Unburned Natural Gas from Residential Stoves in California. Environ. Sci. Technol. 2022, 15828,  DOI: 10.1021/ACS.EST.2C02581
      46
      Composition, Emissions, and Air Quality Impacts of Hazardous Air Pollutants in Unburned Natural Gas from Residential Stoves in California
      Lebel, Eric D.; Michanowicz, Drew R.; Bilsback, Kelsey R.; Hill, Lee Ann L.; Goldman, Jackson S. W.; Domen, Jeremy K.; Jaeger, Jessie M.; Ruiz, Angelica; Shonkoff, Seth B. C.
      Environmental Science & Technology (2022), 56 (22), 15828-15838CODEN: ESTHAG; ISSN:1520-5851. (American Chemical Society)
      The presence of hazardous air pollutants (HAPs) entrained in end-use natural gas (NG) is an understudied source of human health risks. We performed trace gas analyses on 185 unburned NG samples collected from 159 unique residential NG stoves across seven geog. regions in California. Our analyses commonly detected 12 HAPs with significant variability across region and gas utility. Mean regional benzene, toluene, ethylbenzene, and total xylenes (BTEX) concns. in end-use NG ranged from 1.6-25 ppmv-benzene alone was detected in 99% of samples, and mean concns. ranged from 0.7-12 ppmv (max: 66 ppmv). By applying previously reported NG and methane emission rates throughout California's transmission, storage, and distribution systems, we estd. statewide benzene emissions of 4,200 (95% CI: 1,800-9,700) kg yr-1 that are currently not included in any statewide inventories-equal to the annual benzene emissions from nearly 60,000 light-duty gasoline vehicles. Addnl., we found that NG leakage from stoves and ovens while not in use can result in indoor benzene concns. that can exceed the California Office of Environmental Health Hazard Assessment 8-h Ref. Exposure Level of 0.94 ppbv-benzene concns. comparable to environmental tobacco smoke. This study supports the need to further improve our understanding of leaked downstream NG as a source of health risk.
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    42. 42
      Marrero, J. E.; Townsend-Small, A.; Lyon, D. R.; Tsai, T. R.; Meinardi, S.; Blake, D. R. Estimating Emissions of Toxic Hydrocarbons from Natural Gas Production Sites in the Barnett Shale Region of Northern Texas. Environ. Sci. Technol. 2016, 50, 10756– 10764,  DOI: 10.1021/acs.est.6b02827
      47
      Estimating Emissions of Toxic Hydrocarbons from Natural Gas Production Sites in the Barnett Shale Region of Northern Texas
      Marrero, Josette E.; Townsend-Small, Amy; Lyon, David R.; Tsai, Tracy R.; Meinardi, Simone; Blake, Donald R.
      Environmental Science & Technology (2016), 50 (19), 10756-10764CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      Oil and natural gas operations continue to expand and move closer to densely populated areas, contributing to growing public concern regarding exposure to hazardous air pollutants. During the Barnett Shale Coordinated Campaign in Oct., 2013, ground-based whole air samples collected downwind from oil and gas sites showed enhancements in several potentially toxic volatile org. compds. vs. background concns. Molar emissions ratios relative to CH4 were detd. for hexane, benzene, toluene, ethylbenzene, and xylene. Using CH4 leak rates measured from the Picarro mobile flux plane system and a Barnett Shale regional CH4 emissions inventory, rates of emission of these toxic gases were calcd. Benzene emissions were 51 ± 4 to 60 ± 4 kg/h; hexane, the most abundantly emitted pollutant, was 642 ± 45 to 1070 ± 340 kg/h. While obsd. hydrocarbon enhancements fell below federal workplace stds., results indicated a possible link between oil and natural gas operation emissions and hazardous air pollutant exposure concerns. Larger public health risks assocd. with natural gas prodn. and distribution were of particular importance and warranted further investigation, particularly since natural gas use increased in the US and internationally.
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    43. 43
      Jo, W. K.; Pack, K. W. Utilization of Breath Analysis for Exposure Estimates of Benzene Associated with Active Smoking. Environ. Res. 2000, 83, 180– 187,  DOI: 10.1006/enrs.2000.4059
      48
      Utilization of breath analysis for exposure estimates of benzene associated with active smoking
      Jo, Wan-Kuen; Pack, Ku-Won
      Environmental Research (2000), 83 (2), 180-187CODEN: ENVRAL; ISSN:0013-9351. (Academic Press)
      Three different expts. for benzene exposures assocd. with active smoking were carried out. In the first expt., the mean exhaled breath benzene concns. measured 1 min after an active smoke ranged from 58.1-81.3 μg/m3, depending on the com. cigarette brand, while those measured prior to an active smoke ranged from 15.9-19.2 μg/m3. The postexposure breath concns. were much higher than the mean breath concns. reported by some previous studies whose exposure conditions and postsampling times were not controlled. Similar to some previous decay studies conducted for different volatile org. compds. in different microenvironments, the second expt. showed that there was a rapid fall in the breath concn. and thereafter the decrease was much slower. One-compartment half-lives ranged from 30.1-57.8 min. Two-compartment half-lives ranged from 3.2-25.7 min for the first half-life and from 67-462 min for the second half-life. In the final repeated smoke expt. conducted with two specified time intervals, the breath concns. showed increasing trends for both the pre- and the postexposure concns., with few exceptions. However, none of the changes were statistically significant at P<0.05. (c) 2000 Academic Press.
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    44. 44
      Efron, B. Better Bootstrap Confidence Intervals. J. Am. Stat. Assoc. 1987, 82, 171– 185,  DOI: 10.1080/01621459.1987.10478410
      There is no corresponding record for this reference.
    45. 45
      Jung, K.; Lee, J.; Gupta, V.; Cho, G. Comparison of Bootstrap Confidence Interval Methods for GSCA Using a Monte Carlo Simulation. Front. Psychol. 2019, 10, 2215,  DOI: 10.3389/fpsyg.2019.02215
      50
      Comparison of Bootstrap Confidence Interval Methods for GSCA Using a Monte Carlo Simulation
      Jung Kwanghee; Lee Jaehoon; Gupta Vibhuti; Cho Gyeongcheol
      Frontiers in psychology (2019), 10 (), 2215 ISSN:1664-1078.
      Generalized structured component analysis (GSCA) is a theoretically well-founded approach to component-based structural equation modeling (SEM). This approach utilizes the bootstrap method to estimate the confidence intervals of its parameter estimates without recourse to distributional assumptions, such as multivariate normality. It currently provides the bootstrap percentile confidence intervals only. Recently, the potential usefulness of the bias-corrected and accelerated bootstrap (BCa) confidence intervals (CIs) over the percentile method has attracted attention for another component-based SEM approach-partial least squares path modeling. Thus, in this study, we implemented the BCa CI method into GSCA and conducted a rigorous simulation to evaluate the performance of three bootstrap CI methods, including percentile, BCa, and Student's t methods, in terms of coverage and balance. We found that the percentile method produced CIs closer to the desired level of coverage than the other methods, while the BCa method was less prone to imbalance than the other two methods. Study findings and implications are discussed, as well as limitations and directions for future research.
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    46. 46
      Fortmann, R.; Kariher, P.; Clayton, R. Indoor Air Quality: Residual Cooking Exposures ; 2001. (accessed 2022-07-05).
      There is no corresponding record for this reference.
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      Logue, J. M.; McKone, T. E.; Sherman, M. H.; Singer, B. C. Hazard Assessment of Chemical Air Contaminants Measured in Residences. Indoor Air 2011, 21, 92– 109,  DOI: 10.1111/j.1600-0668.2010.00683.x
      52
      Hazard assessment of chemical air contaminants measured in residences
      Logue, J. M.; McKone, T. E.; Sherman, M. H.; Singer, B. C.
      Indoor Air (2011), 21 (2), 92-109CODEN: INAIE5; ISSN:0905-6947. (Wiley-Blackwell)
      Identifying air pollutants that pose a potential hazard indoors can facilitate exposure mitigation. In this study, we compiled summary results from 77 published studies reporting measurements of chem. pollutants in residences in the United States and in countries with similar lifestyles. These data were used to calc. representative mid-range and upper-bound concns. relevant to chronic exposures for 267 pollutants and representative peak concns. relevant to acute exposures for five activity-assocd. pollutants. Representative concns. are compared to available chronic and acute health stds. for 97 pollutants. Fifteen pollutants appear to exceed chronic health stds. in a large fraction of homes. Nine other pollutants are identified as potential chronic health hazards in a substantial minority of homes, and an addnl. nine are identified as potential hazards in a very small percentage of homes. Nine pollutants are identified as priority hazards based on the robustness of measured concn. data and the fraction of residences that appear to be impacted: acetaldehyde; acrolein; benzene; 1,3-butadiene; 1,4-dichlorobenzene; formaldehyde; naphthalene; nitrogen dioxide; and PM2.5. Activity-based emissions are shown to pose potential acute health hazards for PM2.5, formaldehyde, CO, chloroform, and NO2.
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      Torranceair Torrance Air - Monitors; (accessed 2022-09-23).
      There is no corresponding record for this reference.
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      Colorado Department of Public Health and Environment Statement of Errata Air Pollution Control Division ; 2020. (accessed 2022-10-13).
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      Daily Breeze AQMD Starts ‘Extensive Investigation’ of West Torrance Benzene Levels after Air Monitor Detects Spike ; 2020. (accessed 2022-09-23).
      There is no corresponding record for this reference.
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      CBS Colorado Greeley Parents Concerned After Benzene Detected In Air Near Bella Romero Academy ; 2020. (accessed 2022-09-23).
      There is no corresponding record for this reference.
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      Sun, L.; Wallace, L. A. Residential Cooking and Use of Kitchen Ventilation: The Impact on Exposure. J. Air Waste Manage. Assoc. 2021, 71, 830– 843,  DOI: 10.1080/10962247.2020.1823525
      57
      Residential cooking and use of kitchen ventilation: The impact on exposure
      Sun Liu; Wallace Lance A
      Journal of the Air & Waste Management Association (1995) (2021), 71 (7), 830-843 ISSN:.
      Cooking is one of the most significant indoor sources of particles. This study investigated residential cooking and kitchen ventilation behaviors in Canadian homes, using data from 132 households in Halifax and Edmonton. Only 27% of the cooking activities were conducted with added ventilation (range hood use 10%, window opening 15%, and both 2%). The use pattern of the range hood was associated with mealtime and cooking method/device. The frequency of window opening was influenced by season and did not show a clear linkage to ventilation for cooking. Fine particle (PM2.5) decay rates, source strengths, emission masses, and exposure levels were estimated for cooking activities under different ventilation conditions. The results demonstrated the effect of kitchen ventilation on PM2.5 removal. Using a range hood and (or) opening kitchen windows increased the geometric mean (GM) decay rate by a factor of two. The GM source strength from cooking was 0.73 mg min(-1) (geometric standard deviation (GSD) = 4.3) over an average cooking time of 17 minutes (GSD = 2.6). The GM emission mass was 12.6 mg (GSD = 5.3). The GM exposure from a single cooking event was 12 μg m(-3) h (GSD = 6.6). The average number of cooking events per day was 2.4 (SD = 1.5) times. Cooking contributed about 22% to the total daily PM2.5 exposure in participating homes. The frequency and duration of cooking conducted at various temporal scales (mealtime, weekday/weekend, and season), as well as the use of different methods and devices, can support more accurate modeling of the impact of cooking on indoor air quality and human exposure.Implications: The inadequate use of ventilation during cooking highlights the need for educational programs on cooking exposures and ventilation strategies, such as running a range hood fan or opening kitchen windows when possible. Exposures in newly built homes might be a bigger concern than older homes if not providing sufficient ventilation during cooking, due to the tighter building envelopes.
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    53. 53
      Propper, R.; Wong, P.; Bui, S.; Austin, J.; Vance, W.; Alvarado, A.; Croes, B.; Luo, D. Ambient and Emission Trends of Toxic Air Contaminants in California. Environ. Sci. Technol. 2015, 49, 11329,  DOI: 10.1021/acs.est.5b02766
      58
      Ambient and Emission Trends of Toxic Air Contaminants in California
      Propper, Ralph; Wong, Patrick; Bui, Son; Austin, Jeff; Vance, William; Alvarado, Alvaro; Croes, Bart; Luo, Dongmin
      Environmental Science & Technology (2015), 49 (19), 11329-11339CODEN: ESTHAG; ISSN:0013-936X. (American Chemical Society)
      After initiating a toxic air contaminant (TAC) identification and control program in 1984, the California Air Resources Board adopted regulations to reduce TAC emissions from cars, trucks, stationary sources, and consumer products. This work quantifies ambient concn. and emission trends, 1990-2012, for 7 TAC responsible for most known cancer risks assocd. with airborne exposure in California. Of these 7, diesel particulate matter (DPM) is the most important; however, DPM is not directly measured. Based on a novel surrogate method, DPM concns. declined 68%, even though the state population increased 31%, diesel vehicle-miles-traveled increased 81%, and gross state product increased 74%. Based on monitoring data, benzene, 1,3-butadiene, perchloroethylene, and Cr6+ concns. declined 88-94%, and ambient and emissions trends for each of these TAC were similar. These declines generally occurred earlier in California than elsewhere. However, formaldehyde and acetaldehyde, which are photochem. formed in the atm. from volatile org. compds., declined only 20-21%. The collective cancer risk from exposure to these 7 TAC declined 76%. Significant redn. in cancer risk to California residents from air toxics controls implementation, particularly for DPM, is expected to continue.
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    54. 54
      Israeli Ministry of Health Environmental Health in Israel ; 2017. (accessed 2022-07-12).
      There is no corresponding record for this reference.
    55. 55
      ANSES Valeurs Guides de Qualité d’air Intérieur Le Benzène ; 2008. (accessed 2022-07-21).
      There is no corresponding record for this reference.
    56. 56
      Agency for Toxic Substances and Disease Registry Minimal Risk Levels for Hazardous Substances ; 2007. (accessed 2022-09-22).
      There is no corresponding record for this reference.
    57. 57
      Michanowicz, D. R.; Dayalu, A.; Nordgaard, C. L.; Buonocore, J. J.; Fairchild, M. W.; Ackley, R.; Schiff, J. E.; Liu, A.; Phillips, N. G.; Schulman, A.; Magavi, Z.; Spengler, J. D. Home Is Where the Pipeline Ends: Characterization of Volatile Organic Compounds Present in Natural Gas at the Point of the Residential End User. Environ. Sci. Technol. 2022, 56, 10258– 10268,  DOI: 10.1021/acs.est.1c08298
      62
      Home is Where the Pipeline Ends: Characterization of Volatile Organic Compounds Present in Natural Gas at the Point of the Residential End User
      Michanowicz, Drew R.; Dayalu, Archana; Nordgaard, Curtis L.; Buonocore, Jonathan J.; Fairchild, Molly W.; Ackley, Robert; Schiff, Jessica E.; Liu, Abbie; Phillips, Nathan G.; Schulman, Audrey; Magavi, Zeyneb; Spengler, John D.
      Environmental Science & Technology (2022), 56 (14), 10258-10268CODEN: ESTHAG; ISSN:1520-5851. (American Chemical Society)
      The presence of volatile org. compds. (VOCs) in unprocessed natural gas (NG) is well documented; however, the degree to which VOCs are present in NG at the point of end use is largely uncharacterized. We collected 234 whole NG samples across 69 unique residential locations across the Greater Boston metropolitan area, Massachusetts. NG samples were measured for methane (CH4), ethane (C2H6), and nonmethane VOC (NMVOC) content (including tentatively identified compds.) using com. available USEPA anal. methods. Results revealed 296 unique NMVOC constituents in end use NG, of which 21 (or approx. 7%) were designated as hazardous air pollutants. Benzene (bootstrapped mean = 164 ppbv; SD = 16; 95% CI: 134-196) was detected in 95% of samples along with hexane (98% detection), toluene (94%), heptane (94%), and cyclohexane (89%), contributing to a mean total concn. of NMVOCs in distribution-grade NG of 6.0 ppmv (95% CI: 5.5-6.6). While total VOCs exhibited significant spatial variability, over twice as much temporal variability was obsd., with a wintertime NG benzene concn. nearly eight-fold greater than summertime. By using previous NG leakage data, we estd. that 120-356 kg/yr of annual NG benzene emissions throughout Greater Boston are not currently accounted for in emissions inventories, along with an unaccounted-for indoor portion. NG-odorant content (tert-Bu mercaptan and iso-Pr mercaptan) was used to est. that a mean NG-CH4 concn. of 21.3 ppmv (95% CI: 16.7-25.9) could persist undetected in ambient air given known odor detection thresholds. This implies that indoor NG leakage may be an underappreciated source of both CH4 and assocd. VOCs.
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    58. 58
      Background Report Reference AP-42 Section Number: 1.4 Background Chapter: 2 | US EPA; (accessed 2022-12-02).
      There is no corresponding record for this reference.
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      US Environmental Protection Agency AP 42, Fifth Edition, Volume I Chapter 1: External Combustion Sources; (accessed 2022-12-02).
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      US Environmental Protection Agency National Emissions Inventory ; 2017. .
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      Korte, F.; Klein, W. Degradation of Benzene in the Environment. Ecotoxicol. Environ. Saf. 1982, 6, 311– 327,  DOI: 10.1016/0147-6513(82)90046-X
      66
      Degradation of benzene in the environment
      Korte, F.; Klein, W.
      Ecotoxicology and Environmental Safety (1982), 6 (4), 311-27CODEN: EESADV; ISSN:0147-6513.
      A study of benzene (I) [71-43-2] mobility and degrdn. in the environment indicated its ready biodegradability and major importance in atm. chem. The atm half-life of I was <1 day but 50% mineralization in the atm. took approx. 2 days.
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    62. 62
      Zhao, H.; Chan, W. R.; Cohn, S.; Delp, W. W.; Walker, I. S.; Singer, B. C. Indoor Air Quality in New and Renovated Low-Income Apartments with Mechanical Ventilation and Natural Gas Cooking in California. Indoor Air 2021, 31, 717– 729,  DOI: 10.1111/INA.12764
      67
      Indoor air quality in new and renovated low-income apartments with mechanical ventilation and natural gas cooking in California
      Zhao, Haoran; Chan, Wanyu R.; Cohn, Sebastian; Delp, William W.; Walker, Iain S.; Singer, Brett C.
      Indoor Air (2021), 31 (3), 717-729CODEN: INAIE5; ISSN:1600-0668. (Wiley-Blackwell)
      This paper presents pollutant concns. and performance data for code-required mech. ventilation equipment in 23 low-income apartments at 4 properties constructed or renovated 2013-2017. All apartments had natural gas cooking burners. Occupants pledged to not use windows for ventilation during the study but several did. Measured airflows of range hoods and bathroom exhaust fans were lower than product specifications. Only eight apartments operationally met all ventilation code requirements. Pollutants measured over one week in each apartment included time-resolved fine particulate matter (PM2.5), nitrogen dioxide (NO2), formaldehyde and carbon dioxide (CO2) and time-integrated formaldehyde, NO2 and nitrogen oxides (NOx). Compared to a recent study of California houses with code-compliant ventilation, apartments were smaller, had fewer occupants, higher densities, and higher mech. ventilation rates. Mean PM2.5, formaldehyde, NO2, and CO2 were 7.7μg/m3, 14.1, 18.8, and 741 ppm in apartments; these are 4% lower, 25% lower, 165% higher, and 18% higher compared to houses with similar cooking frequency. Four apartments had weekly PM2.5 above the California annual outdoor std. of 12μg/m3 and also discrete days above the World Health Organization 24-h guideline of 25μg/m3. Two apartments had weekly NO2 above the California annual outdoor std. of 30 ppb.
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    63. 63
      Jenkins, P. L.; Phillips, T. J.; Mulberg, E. J.; Hui, S. P. Activity Patterns of Californians: Use of and Proximity to Indoor Pollutant Sources. Atmos. Environ., Part A 1992, 26, 2141– 2148,  DOI: 10.1016/0960-1686(92)90402-7
      68
      Activity patterns of Californians: use of and proximity to indoor pollutant sources
      Jenkins, Peggy L.; Phillips, Thomas J.; Mulberg, Elliot J.; Hui, Steve P.
      Atmospheric Environment, Part A: General Topics (1992), 26A (12), 2141-8CODEN: AEATEN; ISSN:0960-1686.
      The California air Resources board founded a statewide survey of activity patterns of Californians over 11 yr of age to improve the accuracy of exposure assessments for air pollutants. Telephone interviews were conducted with 1762 respondents over the 4 seasons from fall 1987 through summer 1988. In addn. to completing a 24-h recall diary of activities and locations, participants also responded to questions about their use of and proximity to potential pollutant sources. Results are presented regarding time spent by Californians in different activities and locations relevant to pollutant exposure, and their frequency of use of or proximity to pollutant sources including cigarettes, consumer products such as paints and deodorizers, combustion appliances and motor vehicles. The results show that Californians spend, on av., 87% of their time indoors, 7% in enclosed transit and 6% outdoors. At least 62% of the population over 11 yr of age and 46% of nonsmokers are near other tobacco smoke at some time during the day. Potential exposure to different pollutant sources appears to vary among different gender and age groups. For example, women are more likely to use or be near personal care products and household cleaning agents, while men are more likely to be exposed to environmental tobacco smoke, solvents and paints. Data can be used to reduce significantly the uncertainty assocd. with risk assessments for many pollutants.
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  • Supporting Information

    Supporting Information

    The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.est.2c09289.

    • Additional details for air exchange calculations and assumptions underlying calculations of benzene emissions from a single meal; table of p-values for pairwise comparisons of benzene emissions from gas and propane burners on high, on low, and from ovens; summary of attributes of all stoves measured and locations sampled for the study, including the map of sampling locations; floorplans of houses in which bedroom benzene concentrations were measured; kitchen benzene concentrations measured with a hood on and off; photo showing the setup and plot showing results for measurement of benzene emissions from food cooked on an induction stove; benzene emissions from gas stoves plotted against accompanying carbon monoxide emissions; benzene emissions expressed per joule of gas burned; kitchen chamber volumes used in emission rate measurements; image of the sampling setup for emission rate measurements; calculated and actual benzene emissions rates from controlled-release tests; benzene emissions by stove age and brand; gas and propane burner power output; benzene emissions from propane stoves grouped by absolute power output (PDF)


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