Wildland Fires Worsened Population Exposure to PM2.5 Pollution in the Contiguous United States

• Type of Material: Article
• Authors: Danlu Zhang, Emory University; Wenhao Wang, Emory University; Yuzhi Xi, Emory University; Jianzhao Bi, University of Washington, Seattle; Yun Hang, Emory University; Qingyang Zhu, Emory University; Qiang Pu, Emory University; Howard Chang, Emory University; Yang Liu, Emory University
• Language: English
• Date: 2023-11-09
• Publisher: American Chemical Society
• Publication Version: Final Published Version
• Copyright Statement: © 2023 The Authors. Published by American Chemical Society
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): https://doi.org/10.1021/acs.est.3c05143
• Title of Journal or Parent Work: Environmental Science and Technology
• Volume: 57
• Issue: 48
• Start Page: 19990
• End Page: 19998
• Grant/Funding Information: This work was supported by the National Institutes of Health grant 1R01ES034175.
• Keywords: wildfire; air pollution; smoke PM2.5; remote sensing; machine learning
• Research Categories: Environmental Sciences; Health Sciences, Public Health

Abstract

As wildland fires become more frequent and intense, fire smoke has significantly worsened the ambient air quality, posing greater health risks. To better understand the impact of wildfire smoke on air quality, we developed a modeling system to estimate daily PM2.5 concentrations attributed to both fire smoke and nonsmoke sources across the contiguous U.S. We found that wildfire smoke has the most significant impact on air quality in the West Coast, followed by the Southeastern U.S. Between 2007 and 2018, fire smoke contributed over 25% of daily PM2.5 concentrations at ∼40% of all regulatory air monitors in the EPA’s air quality system (AQS) for more than one month per year. People residing outside the vicinity of an EPA AQS monitor (defined by a 5 km radius) were subject to 36% more smoke impact days compared with those residing nearby. Lowering the national ambient air quality standard (NAAQS) for annual mean PM2.5 concentrations to between 9 and 10 μg/m3 would result in approximately 35–49% of the AQS monitors falling in nonattainment areas, taking into account the impact of fire smoke. If fire smoke contribution is excluded, this percentage would be reduced by 6 and 9%, demonstrating the significant negative impact of wildland fires on air quality.