Source contributions to atmospheric organic compound concentrations: Emissions measurements and model predictions

A dilution source sampling system is used to quantify the air pollutant emissions from major urban air pollution sources. The emissions from catalyst-equipped gasoline-powered motor vehicles, noncatalyst gasoline-powered motor vehicles, diesel trucks, meat charbroiling, the cooking of vegetables with seed oils, fireplace combustion of softwood and hardwood, cigarette combustion, and paint spray coating operations are characterized. Semi-volatile and particle-phase organic compounds in the diluted source emissions are collected simultaneously by both a traditional filter/PUF (polyurethane foam) sampling train and by an advanced organic compound-based denuder/filter/PUF sampling train to provide information on the gas/particle phase distribution of the semi-volatile organic compounds. Emission rates of hundreds of organic compounds, spanning carbon numbers from C{dollar}sb1{dollar} to C{dollar}sb{lcub}29{rcub}{dollar} are determined by gas chromatography/mass spectrometry and gas chromatography with flame ionization detection including n-alkanes, isoprenoids and other branched alkanes, cycloalkanes, aromatics, polycylic aromatic hydrocarbons, olefins, n-alkanoic acids, n-alkenoic acids, carbonyls, lactones, petroleum biomarkers, levoglucosan and other wood smoke markers, steroids, and synthetic chemicals. Fine particle mass emission rates and fine particle elemental chemical composition are measured as well.; The emissions profiles collected by use of the dilution source sampler are used to develop receptor-based air quality models that use organic compounds as tracers to determine source contributions to gas-phase and particle-phase air pollutant concentrations in the atmosphere. These models are applied to study source contributions to the existing particulate and gas-phase organic air pollution problems in Southern California and in California's San Joaquin Valley. In the Los Angeles area, diesel engine exhaust, fine particle paved road dust, food cooking operations and wood smoke are the largest contributors to annual average fine particle concentrations in the atmosphere, accompanied by smaller amounts of gasoline-powered vehicle exhaust aerosol, cigarette smoke, tire dust, plant fragments and natural gas combustion aerosol. In the San Joaquin Valley, wood smoke, background aerosol are found to be major contributors to the elevated fine particle concentrations experienced during the winter months.