Special Issue on COVID-19 Aerosol Drivers, Impacts and Mitigation (X)

Jie Li1, Haotian Yang1, Shuping Zha This email address is being protected from spambots. You need JavaScript enabled to view it.2, Nu Yu This email address is being protected from spambots. You need JavaScript enabled to view it.1, Xingang Liu3, Ruofei Sun1 

1 College of Civil Aviation, Nanjing University of Aeronautics and Astronautics, Nanjing 211106, China
2 Wuhu Institute of Technology, Wuhu 241006, China
3 State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, China

Received: July 18, 2020
Revised: October 17, 2020
Accepted: October 21, 2020

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

Download Citation: ||https://doi.org/10.4209/aaqr.2020.07.0416  

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Cite this article:

Li, J., Yang, H., Zha, S., Nu, Y., Liu, X., Sun, R. (2021). Effects of COVID-19 Emergency Response Levels on Air Quality in the Guangdong-Hong Kong-Macao Greater Bay Area, China. Aerosol Air Qual. Res. 21, 200416. https://doi.org/10.4209/aaqr.2020.07.0416


  • The effect of different emergency response levels on air quality was analyzed.
  • The reduction of air pollution was strongly associated with first level response.
  • The higher response level, the more NO2 pollutants will be reduced.


The COVID-19 pandemic has affected air quality due to extreme changes in human behavior. We assessed the air quality response to different emergency levels during different COVID-19 periods and the naught period in the Guangdong-Hong Kong-Macao Greater Bay Area (GBA). We obtained the following conclusions: (1) The measures implemented to prevent and control of COVID-19 directly impacted ambient air pollutants. The air quality index and the concentrations of NO2, PM2.5, PM10, and CO in the GBA for 1–19 January 2020 declined 19.4%, 16.7%, 27.5%, 15.8%, and 25.7%, respectively, compared to the same time period in 2016–2019. (2) The reduction in air pollution was strongly associated with the first-level emergency response during this pandemic. The AQI, NO2, PM2.5, PM10, O3, and CO in the GBA decreased by 37.4%, 47.0%, 40.5%, 44.8%, 6.7%, and 24.1%, respectively. We found no statistically significant difference in the concentrations of different pollutants, except for NO2, during the second- and third-level responses. (3) The higher the emergency response level, the greater the NO2 pollutants reduction. The NO2 concentration was reduced by 47.0%, 25.5%, and 12.1% at emergency response levels 1, 2, and 3, respectively. The results highlight the importance of understanding the role of emergency response in air quality, and provide reference for authorities to formulate more scientific and reasonable emergency responses to epidemic prevention and control.

Keywords: COVID-19, Pandemic, Emergency response, Air pollution, Guangdong-Hong Kong-Macao Greater Bay Area (GBA)

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