Special Issue on Air Quality in a Changed World: Regional, Ambient, and Indoor Air Concentrations from the COVID to Post-COVID Era (II)

Crystal Jane Ethan, Kingsley Katleho Mokoena, Yan Yu This email address is being protected from spambots. You need JavaScript enabled to view it.

School of Public Health, Xi’an Jiaotong University, Health Science Center, Xi’an, Shaanxi 710061, China

Received: October 15, 2021
Revised: December 6, 2021
Accepted: December 6, 2021

 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.210282  

Cite this article:

Ethan, C.J., Mokoena, K.K., Yu, Y. (2022). Air Quality Status in Wuhan City during and One Year after the COVID-19 Lockdown. Aerosol Air Qual. Res. 22, 210282. https://doi.org/10.4209/aaqr.210282


  • China is home to some of the world’s biggest and most populous cities.
  • Ambient air pollution levels in many Chinese cities remain significantly high.
  • Imposed shutdown and restricted movement left a positive impact on the environment.
  • There was a significant increase in air pollution levels after the lockdown.
  • More research should observe changes in air quality during peculiar/major events.


Anthropogenic activities have been established to have severe adverse effects on air quality. Consequently, the nature of daily events, directly and indirectly, influences the nature of air pollution observed. This study focused on describing air quality one year after the Coronavirus (COVID-19) pandemic lockdown (since anthropogenic activities had resumed back to normal) in Wuhan.

Using the independent t-test, the means of air quality index (AQI) and individual air pollutants concentration during the lockdown were compared with the means after the lockdown. Cohen’s d was estimated to quantify the standardized mean difference observed.

Based on the average AQI, the air quality in Wuhan during and after the lockdown was rated “good”; and ranged between 59.7 and 99.8. Indicators of traffic pollution, particularly NO2, were significantly higher after the lockdown; noting a 162% increment in concentration. A 36% increase was also noted for ozone immediately after the lockdown; while a 33% increase was noted for SO2 roughly eight months post lockdown. At different periods post lockdown, particulate matter pollution varied, with some time-spans observing lower concentrations and others higher concentrations than the lockdown. A trade-off effect between PM2.5 and O3 was also noted during and after the lockdown.

One year post the lockdown, air quality in Wuhan has observed some drastic changes. Hence, there is a need for more studies to identify other specific and peculiar sources of emissions in the city. Relevant findings should be employed in supporting the implementation of stringent emission control.

Keywords: Air pollution, COVID-19, Particulate matter, Traffic pollution, Air quality

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