On-Line Characterization of Individual Particles from Automobile Emissions
Received for review December 23, 1996 Revised manuscript received
July 10, 1997 Accepted July 23, 1997 Abstract: This paper presents results from a study showing the first
on-line measurement of the size and chemical
composition of individual particles emitted in automobile
exhaust. Particles sampled directly from the exhaust
pipes
of a number of vehicles upon startup were analyzed using
aerosol time-of-flight mass spectrometry (ATOFMS).
Both
organic and inorganic chemical species including lead,
cerium, platinum, molybdenum, calcium, and sodium were
observed in individual exhaust particles. In general,
a
qualitative correlation exists between particle size and
composition, typified by the presence of predominately
organic species in particles in the fine size mode (<1
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m)
and inorganic species in particles in the coarse size mode
(>1 m). This study demonstrates the potential of
using
ATOFMS for analyzing vehicular exhaust in an on-line
matter. Ultimately, ATOFMS can be used as a real-time
monitor, characterizing particles produced from vehicles
under
a variety of well-defined operating conditions that will
allow for further development of the understanding of
particle
formation and reaction processes. Furthermore,
determi
nation of chemical tracers in individual exhaust particles
will allow for more accurate source allocation of
atmospheric particles.
