The Impact of the COVID-19 Pandemic on Ambient Air Quality in China: A Quasi-Difference-in-Difference Approach

Tuo Zhang and Maogang Tang
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Tuo Zhang: Graduate School of Economics, Kyoto University, Yoshidahonmachi, Sakyo Ward, Kyoto 606-8501, Japan
Maogang Tang: School of Business, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China

IJERPH, 2021, vol. 18, issue 7, 1-19

Abstract: The novel coronavirus (COVID-19) pandemic has provided a distinct opportunity to explore the mechanisms by which human activities affect air quality and pollution emissions. We conduct a quasi-difference-in-differences (DID) analysis of the impacts of lockdown measures on air pollution during the first wave of the COVID-19 pandemic in China. Our study covers 367 cities from the beginning of the lockdown on 23 January 2020 until April 22, two weeks after the lockdown in the epicenter was lifted. Static and dynamic analysis of the average treatment effects on the treated is conducted for the air quality index (AQI) and six criteria pollutants. The results indicate that, first, on average, the AQI decreased by about 7%. However, it was still over the threshold set by the World Health Organization. Second, we detect heterogeneous changes in the level of different pollutants, which suggests heterogeneous impacts of the lockdown on human activities: carbon monoxide (CO) had the biggest drop, about 30%, and nitrogen dioxide (NO 2 ) had the second-biggest drop, 20%. In contrast, ozone (O 3 ) increased by 3.74% due to the changes in the NO x /VOCs caused by the decrease in NO x , the decrease of O 3 titration, and particulate matter concentration. Third, air pollution levels rebounded immediately after the number of infections dropped, which indicates a swift recovery of human activities. This study provides insights into the implementation of environmental policies in China and other developing countries.

Keywords: COVID-19; ambient air quality; air pollution emissions; quasi-difference-in-difference (search for similar items in EconPapers)
JEL-codes: I I1 I3 Q Q5 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (5)

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