Author(s): Jason S. Herringtona, Michael D. Haysa, Barbara J. Georgeb, Richard W. Baldaufa,c
a Office of Research and Development, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, E343-02, Research Triangle Park, NC 27711, USA
b Office of Research and Development, National Exposure Research Laboratory, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, Research Triangle Park, NC 27711, USA
c Office of Transportation and Air Quality, National Vehicle and Fuel Emissions Laboratory, U.S. Environmental Protection Agency, 2000 Traverwood Drive, Ann Arbor, MI 48105, USA
Published By: Atmospheric Environment
Issue: vol. 54
Year of Publication: 2012
Abstract: A thermal extraction-gas chromatography-mass spectrometry (TE-GC-MS) method was utilized to quantitatively examine semivolatile organic compounds (SVOCs) in fine particulate matter (PM2.5) collected from light-duty, gasoline-powered vehicle (LDGV) exhaust. Emissions were analyzed from a subset of 18 vehicles tested in the Kansas City Light-Duty Vehicle Emissions Study (KCVES). The KCVES applied the LA92 Unified Driving Cycle (UDC), consisting of “cold start”, “hot stabilized running”, and “warm start” phases. The sensitivity of the TE-GC-MS analysis provided the opportunity to examine the emission rates and proportions of SVOCs (including polycyclic aromatic hydrocarbons (PAHs), hopanes, and steranes) in PM2.5 on an individual vehicle basis for each UDC phase. Mean target SVOC emissions rates of 5.01 μg km−1, 0.28 μg km−1, and 0.63 μg km−1 were reported for the cold start, hot stabilized running, and warm start phases, respectively. Operating conditions as depicted by each UDC phase significantly affected SVOC emission rates and proportions in PM2.5. The cold start phase emission rates were significantly higher than the hot stabilized running and warm start phases for 89% of the target SVOCs. An increase in SVOC proportions in PM2.5 was observed during the warm start phase compared with the cold start and hot stabilized running phase. This observation was significant for 31% of the target compounds, including chrysene, benzo[a]anthracene, and pyrene. Vehicles tested in both summer and winter provided emissions data describing ambient temperature effects. Emission rates were significantly higher in the winter for 92% of the target SVOCs. Until now, observations of specific SVOCs in motor vehicle emissions produced under changing operating conditions were scant. Such emissions data may be useful for emissions modeling, source apportionment studies, and human exposure assessments.