Laboratory investigation of the fate of diesel emissions in the atmosphere. Task 2. Final report

A series of experiments were performed in Calspan's 600-m/sup 3/ test chamber to quantify the effects of atmosphere containment on the physical, chemical, and biological characteristics of diesel emissions. These experiments included non-aged baseline tests, 8-hour aging tests, with and without uv irradiation and exposure to excess concentrations of ozone (O/sub 3/) and nitrogen dioxide (NO/sub 2/). A single 24-hour aging experiment was also performed. In-situ measurements were made of aerosol size distribution, mass concentrations, scattering coefficients, and gas-phase concentrations of SO/sub 2/, O/sub 3/, NOx, and THC. Aerosol filter samples were obtained at regular intervals during each experiment for a wide variety of analyses, which included: aerosol sulfate and nitrate, total carbon (elemental and organic) and HPLC and Ames Bioassay analyses of the soluble organic fraction derived from aerosol samples. The results of these analyses demonstrated that atmospheric residence can induce changes in diesel exhaust, particularly with respect to the chemical composition and Ames activity of the organic particulate extracts.