Modeling the Concentrations of Gas-Phase Toxic Organic Air Pollutants: Direct Emissions and Atmospheric Formation

摘要

An Eulerian photochemical air quality model is describedudfor the prediction of the atmospheric transport andudchemical 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, andudperchloroethylene 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 productionudcan be a major contributor to the total concentrations ofudsome toxic organic species implies that control programsudfor those species must consider more than just directudemissions.