Observation of elevated air pollutant concentrations in a residential neighborhood of Los Angeles California using a mobile platform

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• 作者：Shishan Hu^a ; ^b ; ^c ; ^{shhu@arb.ca.gov} ; Suzanne E. Paulson^c ; ^{paulson@atmos.ucla.edu} ; Scott Fruin^d ; ^{fruin@usc.edu} ; Kathleen Kozawa^e ; ^{kkozawa@arb.ca.gov} ; Steve Mara^e ; ^{smara@arb.ca.gov} ; Arthur M. Winer^b ; ^{amwiner@ucla.edu}
• 关键词：Vehicle emissions ; Mobile platform ; Exposure assessment ; Ultrafine particle ; Freeway ; New particle formation ; Boyle Heights
• 刊名：Atmospheric Environment
• 出版年：2012
• 期刊代码：11_13522310
• 类别：env
• 出版时间：May, 2012
• 卷：51
• 期：Complete
• 页码：311-319
• 文件大小：1594 K

摘要

We observed elevated air pollutant concentrations, especially of ultrafine particles (UFP), black carbon (BC) and NO, across the residential neighborhood of the Boyle Heights Community (BH) of Los Angeles, California. Using an electric vehicle mobile platform equipped with fast response instruments, real-time air pollutant concentrations were measured in BH in spring and summer of 2008. Pollutant concentrations varied significantly in the two seasons, on different days, and by time of day, with an overall average UFP concentration in the residential areas of 鈭?3鈥?00 cm^鈭?. The averaged UFP, BC, and NO concentrations measured on Soto St, a major surface street in BH, were 57鈥?00 cm^鈭?, 5.1 渭g m^鈭?, and 67 ppb, respectively. Concentrations of UFP across the residential areas in BH were nearly uniform spatially, in contrast to other areas in the greater metropolitan area of Los Angeles where UFP concentrations exhibit strong gradients downwind of roadways. We attribute this 鈥淯FP cloud鈥?to high traffic volumes, including heavy duty diesel trucks on the freeways which surround and traverse BH, and substantial numbers of high-emitting vehicles (HEVs) on the surface streets traversing BH. Additionally, the high density of stop signs and lights and short block lengths, requiring frequent accelerations of vehicles, may contribute. The data also support a role for photochemical production of UFP in the afternoon. UFP concentration peaks (5 s average) of up to 9 million particles cm^鈭? were also observed immediately behind HEVs when they accelerated from stop lights in the BH neighborhood and areas immediately adjacent. Although encounters with HEV during mornings accounted for only about 6%and 17%of time spent monitoring residential areas and major surface streets, HEV contributed to about 28%and 53%of total ultrafine particles measured on the route, respectively. The observation of elevated pollutant concentrations across the Boyle Heights community highlights how multiple factors combine to create high pollutant levels, and has important human exposure assessment implications, including the potential utility of our data as inputs to epidemiological studies.