Development of gas-phase chemistry, secondary organic aerosol, and aqueous-phase chemistry modules for PM modeling. Final report

The Coordinating Research Council (CRC) is sponsoring a multi-phase study to develop improved air quality models for particulate matter (PM). Improved urban and regional scale PM air quality models are needed to develop reliable emission control strategies for areas that exceed the National Ambient Air Quality Standards (NAAQS) for PM-2.5 and PM-10, and for National Parks and other Class 1 areas with impaired visibility. This report describes the development and implementation of two process modules for PM models. These particular process modules are needed to simulate secondary aerosol species, which are often the dominate portion of PM-2.5 mass. The first module simulates the gas-phase atmospheric chemistry of the VOC/NO{sub x}/SO{sub 2}/ozone system and the formation of secondary organic aerosols. The module also simulates the formation of inorganic species, including sulfuric acid and nitric acid, that form important aerosol species: sulfate and nitrate; The second module simulates the aqueous-phase chemistry in fogs and clouds. This chemistry primarily enhances SO{sub 2} oxidation rates and leads to enhanced sulfate aerosol concentrations.