Burden of Cause-Specific Mortality Associated with PM_2.5 Air Pollution in the United States

Importance: Ambient fine particulate matter (PM_2.5) air pollution is associated with increased risk of several causes of death. However, epidemiologic evidence suggests that current knowledge does not comprehensively capture all causes of death associated with PM_2.5 exposure. Objective: To systematically identify causes of death associated with PM_2.5 pollution and estimate the burden of death for each cause in the United States. Design, Setting, and Participants: In a cohort study of US veterans followed up between 2006 and 2016, ensemble modeling was used to identify and characterize morphology of the association between PM_2.5 and causes of death. Burden of death associated with PM_2.5 exposure in the contiguous United States and for each state was then estimated by application of estimated risk functions to county-level PM_2.5 estimates from the US Environmental Protection Agency and cause-specific death rate data from the Centers for Disease Control and Prevention. Main Outcomes and Measures: Nonlinear exposure-response functions of the association between PM_2.5 and causes of death and burden of death associated with PM_2.5. Exposures: Annual mean PM_2.5 levels. Results: A cohort of 4522160 US veterans (4243462 [93.8%] male; median [interquartile range] age, 64.1 [55.7-75.5] years; 3702942 [82.0%] white, 667550 [14.8%] black, and 145593 [3.2%] other race) was followed up for a median (interquartile range) of 10.0 (6.8-10.2) years. In the contiguous United States, PM_2.5 exposure was associated with excess burden of death due to cardiovascular disease (56070.1 deaths [95% uncertainty interval {UI}, 51940.2-60318.3 deaths]), cerebrovascular disease (40466.1 deaths [95% UI, 21770.1-46487.9 deaths]), chronic kidney disease (7175.2 deaths [95% UI, 5910.2-8371.9 deaths]), chronic obstructive pulmonary disease (645.7 deaths [95% UI, 300.2-2490.9 deaths]), dementia (19851.5 deaths [95% UI, 14420.6-31621.4 deaths]), type 2 diabetes (501.3 deaths [95% UI, 447.5-561.1 deaths]), hypertension (30696.9 deaths [95% UI, 27518.1-33881.9 deaths]), lung cancer (17545.3 deaths [95% UI, 15055.3-20464.5 deaths]), and pneumonia (8854.9 deaths [95% UI, 7696.2-10710.6 deaths]). Burden exhibited substantial geographic variation. Estimated burden of death due to nonaccidental causes was 197905.1 deaths (95% UI, 183463.3-213644.9 deaths); mean age-standardized death rates (per 100000) due to nonaccidental causes were higher among black individuals (55.2 [95% UI, 50.5-60.6]) than nonblack individuals (51.0 [95% UI, 46.4-56.1]) and higher among those living in counties with high (65.3 [95% UI, 56.2-75.4]) vs low (46.1 [95% UI, 42.3-50.4]) socioeconomic deprivation; 99.0% of the burden of death due to nonaccidental causes was associated with PM_2.5 levels below standards set by the US Environmental Protection Agency. Conclusions and Relevance: In this study, 9 causes of death were associated with PM_2.5 exposure. The burden of death associated with PM_2.5 was disproportionally borne by black individuals and socioeconomically disadvantaged communities. Effort toward cleaner air might reduce the burden of PM_2.5-associated deaths..