Wildfire smoke PM2.5 and mortality in the contiguous United States

• Type of Material: Article
• Authors: Yiqun Ma, Yale School of Public Health; Emma Zang, Yale School of Public Health; Yang Liu, Emory University; Yuan Lu, Yale New Haven Hospital; Harlan M Krumholz, Yale New Haven Hospital; Michelle L Bell, Yale University; Kai Chen, Yale School of Public Health
• Language: English
• Date: 2023-02-01
• Publisher: NIH
• Publication Version: Preprint (Prior to Peer Review)
• Copyright Statement: The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1101/2023.01.31.23285059
• Title of Journal or Parent Work: medRxiv
• Volume: 2023
• Keywords: United States; mortality; Biological Sciences; Environmental Sciences; wildfire; fine particulate matter

Abstract

Despite the growing evidence on the health effects of wildfire smoke in the western U.S., the nationwide mortality risk and burden attributable to wildfire smoke fine particles (PM2.5) remain unclear. This study aims to investigate the association between wildfire smoke PM2.5 and mortality from all causes, cardiovascular diseases, respiratory diseases, and mental disorders, and calculate the corresponding attributable mortality burden in all 3,108 counties in the contiguous U.S., 2006–2016. Monthly county-level mortality counts were collected from National Center for Health Statistics. Wildfire smoke PM2.5 concentration was derived from a 10×10 km2 resolution spatiotemporal model. Controlling for non-smoke PM2.5, air temperature, and unmeasured spatial and temporal confounders, we found that a 1 μg/m3 increase in smoke PM2.5 was significantly associated with an increase of 0.14% (95% confidence interval [CI]: 0.11%, 0.17%) in all-cause mortality, 0.13% (95% CI: 0.08%, 0.18%) in cardiovascular mortality, 0.16% (95% CI: 0.07%, 0.25%) in respiratory mortality, and 1.08% (95% CI: 0.93%, 1.23%) in mental disorder mortality. Smoke PM2.5 contributed to approximately 1,141 all-cause deaths/year (95% CI: 893, 1,388) in the contiguous U.S., of which over three-fourths were from cardiovascular, respiratory, and mental causes. We found a higher vulnerability among males than females, people aged 0 to 64 years than those ≥ 65 years, and racial/ethnic minorities than non-Hispanic White people. Mild droughts were found to enhance the association between smoke PM2.5 and mortality. Our results indicate that wildfire smoke PM2.5 harms both physical and mental health, which suggests the need for more effective wildfire mitigation strategies and public health responses in the U.S.