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Background: Reductions in ambient concentrations of fine particulate matter (PM2.5) have contributed to reductions in cardiovascular (CV) mortality. Objectives: We examined changes in CV mortality attributed to reductions in emissions from mobile, point, areal, and nonroad sources through changes in concentrations of PM2.5 and its major components nitrates, sulfates, elemental carbon (EC), and organic carbon (OC) in 2,132 U.S. counties between 1990 and 2010. Methods: Using Community Multiscale Air Quality model estimated PM2.5 total and component concentrations, we calculated population-weighted annual averages for each county. We estimated PM2.5 total- and component-related CV mortality, adjusted for county-level population characteristics and baseline PM2.5 concentrations. Using the index of Emission Mitigation Efficiency for primary emission-to-particle pathways, we expressed changes in particle-related mortality in terms of precursor emissions by each sector. Results: PM2.5 reductions represented 5.7% of the overall decline in CV mortality. Large point source emissions of sulfur dioxide accounted for 6.685 95% confidence interval (CI): 5.703, 7.667 fewer sulfate-related CV deaths per 100,000 people. Mobile source emissions of primary EC and nitrous oxides accounted for 3.396 (95% CI: 2.772, 4.020) and 3.984 (95% CI: 2.472, 5.496) fewer CV deaths per 100,000 people respectively. Increased EC and OC emissions from areal sources increased carbon-related CV mortality by 0.788 (95% CI: −0.540, 2.116) and 0.245 (95% CI: −0.697, 1.187) CV deaths per 100,000 people. Discussion: In a nationwide epidemiological study of emission sector contribution to PM2.5–related mortality, we found that reductions in sulfur-dioxide emissions from large point sources and nitrates and EC emissions from mobile sources contributed the largest reduction in particle-related mortality rates respectively. https://doi.org/10.1289/EHP5692
Peterson et al. (Wed,) studied this question.