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Abstract
Biomass and fossil fuel burning impact air quality by injecting fine particulate matter (PM2.5) into the atmosphere, which poses a serious threat to human health. However, the concentration of PM2.5 depends not only on emissions, but also removal. As the planet warms with greenhouse gas increases, the meteorological conditions that remove aerosol, primarily through rainfall and wet deposition, shift in pattern, frequency, and intensity. This combination of factors can worsen air quality purely through meteorological forces, even without changes in emissions. By fixing aerosol emissions at present-day levels in the Community Earth System Model, but increasing greenhouse gases through the 21st century, an increase in PM2.5 (particularly sulfate) is found to be associated largely with precipitation changes. A decrease in wet day frequency (5% globally) contributes to increases in the concentrations of black carbon, primary organic matter, and sulfate (in addition to changes in aqueous production) at the surface.