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Modeling the impact of COVID-19 on air quality in southern California: implications for future control policies

Year: 2021
Type: article
Abstract: . In response to the Coronavirus Disease 2019 (COVID-19), California issued statewide stay-at-home orders, bringing about abrupt and dramatic reductions in air pollutant emissions. This crisis offers us an unprecedented opportunity to evaluate the effectiveness of emission reductions on air quality. Here we use the Weather Research and Forecasting model with Chemistry (WRF-Chem) in combination with surface observations to study the impact of the COVID-19 lockdown measures on air quality in southern California. Based on activity level statistics and satellite observations, we estimate the sectoral emission changes during the lockdown. Due to the reduced emissions, the population-weighted concentrations of fine particulate matter (PM2.5) decrease by 15 % in southern California. The emission reductions contribute 68 % of the PM2.5 concentration decrease before and after the lockdown, while meteorology variations contribute the remaining 32 %. Among all chemical compositions, the PM2.5 concentration decrease due to emission reductions is dominated by nitrate and primary components. For O3 concentrations, the emission reductions cause a decrease in rural areas but an increase in urban areas; the increase can be offset by a 70 % emission reduction in anthropogenic volatile organic compounds (VOC). These findings suggest that a strengthened control on primary PM2.5 emissions and a well-balanced control on nitrogen oxides and VOC emissions are needed to effectively and sustainably alleviate PM2.5 and O3 pollution in southern California.
DOI: 10.5194/acp-21-8693-2021
Authors: Zhe Jiang, Hongrong Shi, Bin Zhao, Yu Gu, Yifang Zhu, Kazuyuki Miyazaki, Xin Lu, Yuqiang Zhang, Kevin W. Bowman, Takashi Sekiya, Kuo-Nan Liou
Institutions: Chinese Academy of Sciences, Institute of Atmospheric Physics, Pacific Northwest National Laboratory, University of California, Los Angeles, California Institute of Technology, Jet Propulsion Laboratory, Duke University, Japan Agency for Marine-Earth Science and Technology
Language: English
Open Access status: gold
Estimated APC paid: $1,725
Funders: National Science Foundation, U.S. Department of Energy, National Aeronautics and Space Administration, California Institute of Technology, National Natural Science Foundation of China, Chinese Academy of Sciences, Youth Innovation Promotion Association of the Chinese Academy of Sciences, State Key Laboratory of Resources and Environmental Information System, National Oceanic and Atmospheric Administration, Jet Propulsion Laboratory, Youth Innovation Promotion Association
Awards: G4971983805, Radiative Transfer through the Black Carbon-Snow System: Fundamentals and Applications, G5398742571, G6195818568, G7966895750, G994406523
OpenAlex ID: W3125132311
FWCI: 4.715
Cites: 59
Cited by: 53
Related to: 10