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Dominance of Wildfires Impact on Air Quality Exceedances during the 2020 Record-Breaking Wildfire Season in the United States
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  • Yunyao Li,
  • Daniel Tong,
  • Siqi Ma,
  • Xiaoyang Zhang,
  • Shobha Kondragunta,
  • Fangjun Li,
  • Rick D. Saylor
Yunyao Li
George Mason University

Corresponding Author:[email protected]

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Daniel Tong
George Mason University
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Siqi Ma
George Mason University
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Xiaoyang Zhang
South Dakota State University
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Shobha Kondragunta
National Oceanic and Atmospheric Administration (NOAA)
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Fangjun Li
Geospatial Sciences Center of Excellence (GSCE), South Dakota State University
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Rick D. Saylor
National Oceanic and Atmospheric Administration (NOAA)
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Abstract

The western United States experienced a record-breaking wildfire season in 2020. This study quantifies the contribution of wildfire emissions to the exceedances of health-based National Ambient Air Quality Standard (NAAQS) for fine particles (PM2.5) by comparing two CMAQ simulations, with and without wildfire emissions. During August to October 2020, western wildfires contributed 23% of surface PM2.5 in the contiguous US (CONUS), with a larger contribution in Pacific Coast (43%) and Mountain Region (42%). Consequently, wildfires were the primary contributor to the 3,720 observed exceedances. The wildfire influence peaked on September 14th, 2020, when 273 exceedances were recorded and wildfire emissions contributed 41%, 81%, and 72% to surface PM2.5 concentrations in the CONUS, Pacific Coast, and Mountain regions, respectively. Our finding highlights the predominating influence of wildfires on air quality, and potentially human health, that is expected to grow with increasing fire activities, while anthropogenic emissions decrease.
16 Nov 2021Published in Geophysical Research Letters volume 48 issue 21. 10.1029/2021GL094908