Burden of Cause-Specific Mortality Associated With PM<sub>2.5</sub> Air Pollution in the United States
Authors: Benjamin Bowe, Yan Xie, Yan Yan, Ziyad Al-Aly
Journal: JAMA Network Open (2019)

<h3>Importance</h3> Ambient fine particulate matter (PM<sub>2.5</sub>) 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<sub>2.5</sub>exposure. <h3>Objective</h3> To systematically identify causes of death associated with PM<sub>2.5</sub>pollution and estimate the burden of death for each cause in the United States. <h3>Design, Setting, and Participants</h3> 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<sub>2.5</sub>and causes of death. Burden of death associated with PM<sub>2.5</sub>exposure in the contiguous United States and for each state was then estimated by application of estimated risk functions to county-level PM<sub>2.5</sub>estimates from the US Environmental Protection Agency and cause-specific death rate data from the Centers for Disease Control and Prevention. <h3>Main Outcomes and Measures</h3> Nonlinear exposure-response functions of the association between PM<sub>2.5</sub>and causes of death and burden of death associated with PM<sub>2.5</sub>. <h3>Exposures</h3> Annual mean PM<sub>2.5</sub>levels. <h3>Results</h3> A cohort of 4 522 160 US veterans (4 243 462 [93.8%] male; median [interquartile range] age, 64.1 [55.7-75.5] years; 3 702 942 [82.0%] white, 667 550 [14.8%] black, and 145 593 [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<sub>2.5</sub>exposure was associated with excess burden of death due to cardiovascular disease (56 070.1 deaths [95% uncertainty interval {UI}, 51 940.2-60 318.3 deaths]), cerebrovascular disease (40 466.1 deaths [95% UI, 21 770.1-46 487.9 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 (19 851.5 deaths [95% UI, 14 420.6-31 621.4 deaths]), type 2 diabetes (501.3 deaths [95% UI, 447.5-561.1 deaths]), hypertension (30 696.9 deaths [95% UI, 27 518.1-33 881.9 deaths]), lung cancer (17 545.3 deaths [95% UI, 15 055.3-20 464.5 deaths]), and pneumonia (8854.9 deaths [95% UI, 7696.2-10 710.6 deaths]). Burden exhibited substantial geographic variation. Estimated burden of death due to nonaccidental causes was 197 905.1 deaths (95% UI, 183 463.3-213 644.9 deaths); mean age-standardized death rates (per 100 000) 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<sub>2.5</sub>levels below standards set by the US Environmental Protection Agency. <h3>Conclusions and Relevance</h3> In this study, 9 causes of death were associated with PM<sub>2.5</sub>exposure. The burden of death associated with PM<sub>2.5</sub>was disproportionally borne by black individuals and socioeconomically disadvantaged communities. Effort toward cleaner air might reduce the burden of PM<sub>2.5</sub>-associated deaths.