Dept. of Environmental Science
Oregon Graduate Center
The model and the statistical and experimental techniques for using gaseous species to trace sources of particulate air pollution are developed. The model is implemented in a simple environment and the results are compared with those obtained from the concurrent application of other models. In particular, measurements of elevated concentrations of the gas methyl chloride, CH3Cl, in the Portland, Oregon area are used to quantify the contribution of residential wood combustion to fine particulate pollution. The method requires accurate measurements of the gas to aerosol ratios in the source emissions and knowledge of all sources contributing to the ambient concentrations of the gases. The source emission factors for the ratio of CH3Cl to aerosol from woodburning are presented for different types of wood and burn conditions along with measurements of the background concentrations of CH3Cl at both an urban and a remote global site. The advantages of using gaseous tracers to apportion the sources of particulate pollution include: (1) the continuous in situ monitoring which provides real time estimates of the source contributions and therefore of personal exposures, and (2) the inclusion of a gaseous species, such as CH3Cl for woodburning, in the multicomponent Chemical Mass Balance (CMB) receptor model can help distinguish source contributions among sources with similar elemental characterizations. The results of using CH3Cl to estimate the contribution of wood burning to particulate air pollution show that the evening, wintertime averaged concentrations of fine particles from woodburning ranges from 10 Âµg/m[superscript 3] in a hilly, windy neighborhood to 50-73 Âµg/m[superscript 3] in neighborhoods on low terrain subject to poor meteorological dispersion. Woodburning emissions may be a major cause of the nonattainment of air quality standards in many urban areas. The uncertainty of the woodburning contribution using CH3Cl measurements is generally less than 30 %. The implications of applying the CH3Cl model suggest an important health risk from woodsmoke may be that of acute exposure to more susceptible members of the population. A greater health concern exists over exposure to woodsmoke in developing countries where cooking with biomass fuels in rooms with little ventilation is common.
Edgerton, Sylvia Anne, "Gaseous tracers in receptor modeling: methyl chloride emission from wood combustion" (1985). Scholar Archive. 80.