Modeling the Concentrations of Gas-Phase Toxic Organic Air Pollutants: Direct Emissions and Atmospheric Formation
An Eulerian photochemical air quality model is described for the prediction of the atmospheric transport and chemical reactions of gas-phase toxic organic air pollutants. Model performance was examined in the Los Angeles, CA, area over the period August 27-28, 1987. The organic compounds were drawn from a list of 189 species selected for control as hazardous air pollutants in the Clean Air Act amendments of 1990. The species considered include benzene, various alkylbenzenes, phenol, cresols, 1,3- butadiene, acrolein, formaldehyde, acetaldehyde, and perchloroethylene among others. It is found that photochemical generation contributes significantly to form-aldehyde, acetaldehyde, acetone, and acrolein concentrations for the 2-day period studied. Phenol concentrations are dominated by direct emissions, despite the existence of a pathway for atmospheric formation from benzene oxidation. The finding that photochemical production can be a major contributor to the total concentrations of some toxic organic species implies that control programs for those species must consider more than just direct emissions.
© 1993 American Chemical Society. Received for review March 25, 1993. Revised manuscript received September 9, 1993. Accepted September 13, 1993. The authors thank Dr. W. P. L. Carter of the University of California at Riverside for his assistance. This research was supported by the Electric Power Research Institute under Agreement RP3189-3.
Supplemental Material - es00050a013_si_001.pdf