Long-term mortality burden trends attributed to black carbon and PM from wildfire emissions across the continental USA from 2000 to 2020: a deep learning modelling study

Jing Wei, Department of Chemical and Biochemical Engineering, Iowa Technology Institute, Center for Global and Regional Environmental Research, University of Iowa, Iowa City, IA, USA; Department of Atmospheric and Oceanic Science, Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD, USA. Electronic address: weijing@umd.edu.
Jun Wang, Department of Chemical and Biochemical Engineering, Iowa Technology Institute, Center for Global and Regional Environmental Research, University of Iowa, Iowa City, IA, USA. Electronic address: jun-wang-1@uiowa.edu.
Zhanqing Li, Department of Atmospheric and Oceanic Science, Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD, USA. Electronic address: zhanqing@umd.edu.
Shobha Kondragunta, Center for Satellite Applications and Research, NOAA National Environmental Satellite, Data, and Information Service, College Park, MD, USA.
Susan Anenberg, Department of Environmental and Occupational Health, George Washington University, Washington, DC, USA.
Yi Wang, Department of Chemical and Biochemical Engineering, Iowa Technology Institute, Center for Global and Regional Environmental Research, University of Iowa, Iowa City, IA, USA.
Huanxin Zhang, Department of Chemical and Biochemical Engineering, Iowa Technology Institute, Center for Global and Regional Environmental Research, University of Iowa, Iowa City, IA, USA.
David Diner, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA.
Jenny Hand, Cooperative Institute for Research in the Atmosphere, Colorado State University, Fort Collins, CO, USA.
Alexei Lyapustin, Climate and Radiation Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, USA.
Ralph Kahn, Climate and Radiation Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, USA.
Peter Colarco, Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center, Greenbelt, MD, USA.
Arlindo da Silva, Global Modeling and Assimilation Office, NASA Goddard Space Flight Center, Greenbelt, MD, USA.
Charles Ichoku, Department of Geography and Environmental Systems, University of Maryland Baltimore County, Baltimore, MD, USA.

Document Type

Journal Article

Publication Date

12-1-2023

Journal

The Lancet. Planetary health

Volume

7

Issue

12

DOI

10.1016/S2542-5196(23)00235-8

Abstract

BACKGROUND: Long-term improvements in air quality and public health in the continental USA were disrupted over the past decade by increased fire emissions that potentially offset the decrease in anthropogenic emissions. This study aims to estimate trends in black carbon and PM concentrations and their attributable mortality burden across the USA. METHODS: In this study, we derived daily concentrations of PM and its highly toxic black carbon component at a 1-km resolution in the USA from 2000 to 2020 via deep learning that integrated big data from satellites, models, and surface observations. We estimated the annual PM-attributable and black carbon-attributable mortality burden at each 1-km grid using concentration-response functions collected from a national cohort study and a meta-analysis study, respectively. We investigated the spatiotemporal linear-regressed trends in PM and black carbon pollution and their associated premature deaths from 2000 to 2020, and the impact of wildfires on air quality and public health. FINDINGS: Our results showed that PM and black carbon estimates are reliable, with sample-based cross-validated coefficients of determination of 0·82 and 0·80, respectively, for daily estimates (0·97 and 0·95 for monthly estimates). Both PM and black carbon in the USA showed significantly decreasing trends overall during 2000 to 2020 (22% decrease for PM and 11% decrease for black carbon), leading to a reduction of around 4200 premature deaths per year (95% CI 2960-5050). However, since 2010, the decreasing trends of fine particles and premature deaths have reversed to increase in the western USA (55% increase in PM, 86% increase in black carbon, and increase of 670 premature deaths [460-810]), while remaining mostly unchanged in the eastern USA. The western USA showed large interannual fluctuations that were attributable to the increasing incidence of wildfires. Furthermore, the black carbon-to-PM mass ratio increased annually by 2·4% across the USA, mainly due to increasing wildfire emissions in the western USA and more rapid reductions of other components in the eastern USA, suggesting a potential increase in the relative toxicity of PM. 100% of populated areas in the USA have experienced at least one day of PM pollution exceeding the daily air quality guideline level of 15 μg/m during 2000-2020, with 99% experiencing at least 7 days and 85% experiencing at least 30 days. The recent widespread wildfires have greatly increased the daily exposure risks in the western USA, and have also impacted the midwestern USA due to the long-range transport of smoke. INTERPRETATION: Wildfires have become increasingly intensive and frequent in the western USA, resulting in a significant increase in smoke-related emissions in populated areas. This increase is likely to have contributed to a decline in air quality and an increase in attributable mortality. Reducing fire risk via effective policies besides mitigation of climate warming, such as wildfire prevention and management, forest restoration, and new revenue generation, could substantially improve air quality and public health in the coming decades. FUNDING: National Aeronautics and Space Administration (NASA) Applied Science programme, NASA MODIS maintenance programme, NASA MAIA satellite mission programme, NASA GMAO core fund, National Oceanic and Atmospheric Administration (NOAA) GEO-XO project, NOAA Atmospheric Chemistry, Carbon Cycle, and Climate (AC4) programme, and NOAA Educational Partnership Program with Minority Serving Institutions.

Department

Environmental and Occupational Health

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