Impact of Reductions in Emissions from Major Source Sectors on Fine Particulate Matter-Related Cardiovascular Mortality

Background: Reductions in ambient concentrations of fine particulate matter ([PM.sub.2.5]) 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 [PM.sub.2.5] 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 [PM.sub.2.5] total and component concentrations, we calculated population-weighted annual averages for each county. We estimated [PM.sub.2.5] total- and component-related CV mortality, adjusted for county-level population characteristics and baseline [PM.sub.2.5] 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: [PM.sub.2.5] 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 [PM.sub.2.5]-related mortality, we found that reductions in sulfurdioxide 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
Introduction The Clean Air Act Amendments of 1990 led to the establishment of national, regional, and source-specific regulations that significantly decreased ambient concentrations of fine particulate matter ([PM.sub.2.5]) in many [...]