Opposite impact of emission reduction during the COVID-19 lockdown period on the surface concentrations of PM2.5 and O3 in Wuhan, China

Hao Yin, Cheng Liu*, Qihou Hu, Ting Liu, Shuntian Wang, Meng Gao, Shiqi Xu, Chengxin Zhang, Wenjing Su

*Corresponding author for this work

    Research output: Contribution to journalJournal articlepeer-review

    53 Citations (Scopus)

    Abstract

    To prevent the spread of the COVID-19 epidemic, the Chinese megacity Wuhan has taken emergent lockdown measures starting on January 23, 2020. This provided a natural experiment to investigate the response of air quality to such emission reductions. Here, we decoupled the influence of meteorological and non-meteorological factors on main air pollutants using generalized additive models (GAMs), driven by data from the China National Environmental Monitoring Center (CNEMC) network. During the lockdown period (Jan. 23 – Apr. 8, 2020), PM2.5, PM10, NO2, SO2, and CO concentrations decreased significantly by 45 %, 49 %, 56 %, 39 %, and 18 % compared with the corresponding period in 2015–2019, with contributions by S(meteos) of 15 %, 17 %, 13 %, 10 %, and 6 %. This indicates an emission reduction of NOx at least 43 %. However, O3 increased by 43 % with a contribution by S(meteos) of 6 %. In spite of the reduced volatile organic compound (VOC) emissions by 30 % during the strict lockdown period (Jan. 23 – Feb. 14, 2020), which likely reduced the production of O3, O3 concentrations increased due to a weakening of the titration effect of NO. Our results suggest that conventional emission reduction (NOx reduction only) measures may not be sufficient to reduce (or even lead to an increase of) surface O3 concentrations, even if reaching the limit, and VOC-specific measures should also be taken.

    Original languageEnglish
    Article number117899
    Number of pages11
    JournalEnvironmental Pollution
    Volume289
    Early online date2 Aug 2021
    DOIs
    Publication statusPublished - 15 Nov 2021

    Scopus Subject Areas

    • Toxicology
    • Pollution
    • Health, Toxicology and Mutagenesis

    User-Defined Keywords

    • Atmospheric pollution
    • Generalized additive models
    • Meteorological factors influence
    • Titration effect
    • VOC reduction

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