Environ Sci Technol 2019 03 12;53(5):2595-2611. Epub 2019 Feb 12.
Department of Physics and Atmospheric Science , Dalhousie University , 6300 Coburg Road , Halifax , Nova Scotia B3H 3J5 , Canada.
An accurate fine-resolution surface of the chemical composition of fine particulate matter (PM) would offer valuable information for epidemiological studies and health impact assessments. We develop geoscience-derived estimates of PM composition from a chemical transport model (GEOS-Chem) and satellite observations of aerosol optical depth, and statistically fuse these estimates with ground-based observations using a geographically weighted regression over North America to produce a spatially complete representation of sulfate, nitrate, ammonium, black carbon, organic matter, mineral dust, and sea-salt over 2000-2016. Significant long-term agreement is found with cross-validation sites over North America (R = 0.57-0.96), with the strongest agreement for sulfate (R = 0.96), nitrate (R = 0.90), and ammonium (R = 0.86). We find that North American decreases in population-weighted fine particulate matter (PM) concentrations since 2000 have been most heavily influenced by regional changes in sulfate and organic matter. Regionally, the relative importance of several chemical components are found to change with PM concentration, such as higher PM concentrations having a larger proportion of nitrate and a smaller proportion of sulfate. This data set offers information for research into the health effects of PM chemical components.