Differential Reductions in Total and Compositional PM2.5 Exposure across Socioeconomic and Demographic Groups from Emission Source Mitigation in Canada (2007-2016).

Fine particulate matter (PM2.5) is a leading risk factor for morbidity and mortality worldwide. Recent studies have shown substantial heterogeneity in exposure to PM2.5 within populations, with socially disadvantaged subgroups exhibiting disproportionally higher exposure. However, the extent to which reductions in PM2.5 and its components may differentially affect these subgroups remains unclear. Leveraging state-of-the-art exposure surfaces that simulate annual reductions in total and compositional PM2.5 from major emission sectors under two policy scenarios (20% and 100%), based on satellite observations and a global chemical transport model, we characterized the expected reductions in total and compositional population-weighted PM2.5 exposure by selected subgroups for 2007 and 2016. Under both scenarios, we found that certain subgroups, particularly low-income people, immigrants, and racialized groups, would experience larger reductions in exposure to total and compositional PM2.5. The largest decreases were associated with nitrates, sulfates, and ammonia from agriculture, nitrates and black carbon from transportation, and organic matter from residential wood combustion. These findings have important implications for PM2.5 mitigation strategies aimed at reducing population exposure and associated disparities in Canada.