16 Nov 2020
16 Nov 2020
COVID-19 lockdowns highlight a risk of increasing ozone pollution in European urban areas
- 1Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland
- 2Wolfson Atmospheric Chemistry Laboratories, University of York, York, YO10 5DD, United Kingdom
- 3National Centre for Atmospheric Science, University of York, Heslington, York, YO10 5DD, United Kingdom
- 4Ricardo Energy & Environment, Harwell, Oxfordshire, OX11 0QR, United Kingdom
- 1Empa, Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, 8600 Dübendorf, Switzerland
- 2Wolfson Atmospheric Chemistry Laboratories, University of York, York, YO10 5DD, United Kingdom
- 3National Centre for Atmospheric Science, University of York, Heslington, York, YO10 5DD, United Kingdom
- 4Ricardo Energy & Environment, Harwell, Oxfordshire, OX11 0QR, United Kingdom
Abstract. In March 2020, non-pharmaceutical interventions in the form of lockdowns were applied across Europe to urgently reduce the transmission of SARS-CoV-2, the virus which causes the COVID-19 disease. The near-complete shutdown of the European economy had widespread impacts on atmospheric composition, particularly for nitrogen dioxide (NO2) and ozone (O3). To investigate these changes, we analyze data from 246 ambient air pollution monitoring sites in 102 urban areas and 34 countries in Europe between February and July, 2020. Counterfactual, business as usual air quality time series are created using machine learning models to account for natural weather variability. Across Europe, we estimate that NO2 concentrations were 34 and 32 % lower than expected for traffic and urban-background locations while O3 was 30 and 21 % higher (in the same environments) at the point of maximum restriction on mobility. The European urban NO2 experienced in the 2020 lockdown was equivalent to that which might be anticipated in 2028 based on average trends since 2010. Despite NO2 concentrations decreasing by approximately a third, total oxidant (Ox) changed little, suggesting that the reductions of NO2 were substituted by increases in O3. The lockdown period demonstrated that the expected future reductions in NO2 in European urban areas are likely to lead to a widespread increase in urban O3 pollution unless additional mitigation measures are introduced.
Stuart K. Grange et al.


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RC1: 'Comments to Grange et al.', Anonymous Referee #1, 18 Dec 2020
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RC2: 'Review comments on ACP-2020-1171', Shaojun Zhang, 30 Dec 2020
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AC1: 'Comment on acp-2020-1171', Stuart Grange, 29 Jan 2021


-
RC1: 'Comments to Grange et al.', Anonymous Referee #1, 18 Dec 2020
-
RC2: 'Review comments on ACP-2020-1171', Shaojun Zhang, 30 Dec 2020
-
AC1: 'Comment on acp-2020-1171', Stuart Grange, 29 Jan 2021
Stuart K. Grange et al.
Stuart K. Grange et al.
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what would have beenwithout the lockdowns. Nitrogen dioxide (NO2), an important vehicle-sourced pollutant, decreased by a third. However, ozone (O3) increased in response to the lower NO2. Because NO2 is decreasing over time, increases in O3 can be expected in European urban areas and will require management to avoid future negative outcomes.