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

I-Chien Lai1, Peter Brimblecombe This email address is being protected from spambots. You need JavaScript enabled to view it.1,2

1 Aerosol Science Research Center, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan
2 Department of Marine Environment and Engineering, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan

Received: July 11, 2020
Revised: October 20, 2020
Accepted: October 22, 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.2020.07.0392  

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Cite this article:

Lai, I.C., Brimblecombe, P. (2021). Long-range Transport of Air Pollutants to Taiwan during the COVID-19 Lockdown in Hubei Province. Aerosol Air Qual. Res. 21, 200392. https://doi.org/10.4209/aaqr.2020.07.0392


  • Remote NOx and PM2.5 were lower during lockdown 2020 compared with 2018/19.
  • Kinmen and Matsu close to Mainland cities revealed larger changes.
  • Trajectories from Hubei province showed reductions most clearly.
  • O3 showed higher concentrations under trajectories from Northern China.


Lockdown implemented to limit transmission of the COVID-19 virus in China reduced the emissions of air pollutants especially around Hubei Province, though restrictions were more widely applied across the country. Air over Taiwan may be affected by emissions from mainland China so the changes provided an opportunity to detect the effect of long-range pollutant transport to Taiwan, especially at remote sites. Small decreases were observed in NOx and PM2.5 concentrations, when comparing 2020 with earlier years, as well as some hints of increases in O3. Back trajectories from China were used to select days when this effect would be strongest and showed clearer evidence of reductions at remote sites in Taiwan. These were strongest for NOx and PM2.5 in Kinmen and Matsu, close to the Fujian coast, but the effects were seen even on Magong in the Penghu archipelago and at Cape Fugui at the very north of Taiwan. Larger reductions on the coastal islands is not surprising given their proximity to major cities, but on Magong and at Cape Fugui, PM2.5 concentrations are reduced by a few micrograms per cubic metre. Decreases in NOx are smaller and at Cape Fugui, barely amounting to a ppb. Changes in O3 are distinctive, showing concentration increases of around 20% under trajectories deriving from Northern China, in keeping with observations that reductions in NOx lead to substantial increases in O3. Overall, there was only a small reduction in NOx and PM in Taiwan. Although these changes in pollutant concentrations may be relatively large in remote areas, they are not likely to have a major effect on cumulative exposure in larger cities, where concentrations of these pollutants can be high. Nevertheless, the observations support calls for agreement over emission reductions to lessen pollutant transfer across the Taiwan Strait.

Keywords: Ozone, Carbon monoxide, Particulate matter, Nitrogen oxides

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