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Air pollution impacts of COVID-19–related containment measures

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Science Advances  21 May 2021:
Vol. 7, no. 21, eabe1178
DOI: 10.1126/sciadv.abe1178
  • Fig. 1 Changes in population-weighted, regionally averaged NO2 concentration per unit lockdown policy stringency index based on ground monitor data.

    Countries in dark gray are not included in the analysis due to the unavailability of monitor data. Hatched regions lack data on more than 10% of the days from 1 January 2016 to 6 July 2020 and are excluded from the results. In dotted regions, changes in population exposure to NO2 with stringency are not statistically significant at the 5% level.

  • Fig. 2 Changes in ozone as a function of the HCHO-to-NO2 ratio.

    (A) Changes in ozone by region as a function of the HCHO-to-NO2 ratio. Circles, squares, and triangles represent European regions, Chinese provinces, and U.S. states, respectively, where NO2 decreases are found to be statistically significant. (B) Cumulative share of the regions in the “extended transition regime” (1 < HCHO/NO2 < 4) with a decrease in ozone as a function of the HCHO-to-NO2 ratio based on pre-lockdown conditions. We find a gradual transition regime between a HCHO-to-NO2 ratio of 1 and 4. The blue line can be interpreted as the probability that a region at a given HCHO-to-NO2 ratio will experience a decrease in ozone given a decrease in NO2. Not all regions with reduced NO2 due to the lockdown have reduced ozone, as HCHO levels also vary (figs. S5 and S6).

  • Fig. 3 Mortality rate per million people due to COVID-19 (gray) and air quality improvements due to COVID-19–related lockdown measures (blue).

    All pollutants (PM2.5, NO2, and ozone) are included.

Supplementary Materials

  • Supplementary Materials

    Air pollution impacts of COVID-19–related containment measures

    Guillaume P. Chossière, Haofeng Xu, Yash Dixit, Stewart Isaacs, Sebastian D. Eastham, Florian Allroggen, Raymond L. Speth, Steven R. H. Barrett

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    The PDF file includes:

    • Figs. S1 to S16
    • Legend for table S1
    • Table S2
    • Code files are available at: https://zenodo.org/record/4553547 (DOI: 10.5281/zenodo.4553547).

    Other Supplementary Material for this manuscript includes the following:

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