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Title: Comparison of emission inventory and ambient concentration ratios of CO, NMOG, and NO sub x in California South Coast Air Basin

Journal Article · · Journal of the Air and Waste Management Association; (United States)
; ; ;  [1]; ;  [2]
  1. California Air Resources Board, Sacramento, CA (United States)
  2. Sonoma Technology Inc., Santa Rosa, CA (United States)

In the present study, the author performed a top-down validation of the reactive organic gas and carbon monoxide emission inventories for California's South Coast Air Basin by comparing speciation profiles for nonmethane organic gases (NMOG) and ratios of CO/NO{sub x} and NMOG/NO{sub x} derived from early-morning (0700 to 0800) ambient measurements taken during the 1987 Southern California Air Quality Study with the corresponding ratios and speciation profiles derived from day-specific, hourly, gridded emission inventories. Twenty separate comparisons were considered for each ratio, each representing a different combination of season, emission category, and spatial and temporal averaging of emissions. It was determined that the most appropriate comparison in summer was ambient pollutant ratios with ratios derived from morning on-road motrovehicle emission inventories, and in the fall, ambient ratios with ratios derived from overnight on-road motor vehicle emission inventories with some contribution from overnight stationary-source NO{sub x} emission inventories. From these comparisons, the ambient CO/CO{sub x} and NMOG/NO{sub x} ratios are about 1.5 and 2 to 2.5 times higher, respectively, than the corresponding inventory ratios. On the assumption that inventories of NO{sub x} emissions are reasonably correct, these results indicate that on-road motor vehicle CO and NMOG emissions are significantly underestimated. Comparisons of measured CO, NMOG, and NO{sub x} concentrations and CO/NO{sub x} and NMOG/NO{sub x} ratios with air quality model predictions obtained by the California Air Resources Board show similar differences.

OSTI ID:
7045877
Journal Information:
Journal of the Air and Waste Management Association; (United States), Vol. 42:3; ISSN 1047-3289
Country of Publication:
United States
Language:
English