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https://doi.org/10.5194/acp-2020-755
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/acp-2020-755
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

  12 Oct 2020

12 Oct 2020

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This preprint is currently under review for the journal ACP.

Impacts of the COVID-19 lockdown on air pollution at regional and urban background sites in northern Italy

Jean-Philippe Putaud1, Luca Pozzoli1, Enrico Pisoni1, Sebastiao Martins Dos Santos1, Friedrich Lagler1, Guido Lanzani2, Umberto Dal Santo2, and Augustin Colette3 Jean-Philippe Putaud et al.
  • 1European Commission, Joint Research Centre (JRC), Ispra, Italy
  • 2Agenzia Regionale per la Protezione dell'Ambiente (ARPA-Lombardia), Milan, Italy
  • 3Institut National de l'Environnement Industriel et des Risques (INERIS), Verneuil-en-Halatte, France

Abstract. The COVID-19 lockdown measures gradually implemented in Lombardy (northern Italy) from 23 February 2020 led to a downturn in several economic sectors with possible impacts on air quality. Several communications claimed in the first weeks of March 2020 that the mitigation in air pollution observed at that time was actually related to these lockdown measures, without considering that seasonal variations in emissions and meteorology also influence air quality. To determine the specific impact of lockdown measures on air quality in northern Italy, we compared observations from the European Commission atmospheric observatory of Ispra (regional background) and from the regional environmental protection agency (ARPA) air monitoring stations in the Milan conurbation (urban background) with expected values for these observations using two different approaches. On the one hand, intensive aerosol variables determined from specific aerosol characterisation observations performed in Ispra were compared to their 3-year averages. On the other hand, measured concentrations of atmospheric pollutants (NO2, PM10, O3, NO, SO2) were compared to expected concentrations derived from the Copernicus Atmosphere Monitoring Service Regional (CAMS) ensemble model forecasts, which did not account for lockdown measures. From these comparisons, we show that NO2 concentrations decreased as a consequence of the lockdown by −30 % and −40 % on average at the urban and regional background sites, respectively. Unlike NO2, PM10 concentrations were not significantly affected by lockdown measures. This could be due to any decreases in PM10 (and PM10 precursors) emissions from traffic being compensated for by increases in emissions from domestic heating and/or from changes in the secondary aerosol formation regime resulting from the lockdown measures. The implementation of the lockdown measures also led to an increase in the highest O3 concentrations at both the urban and regional background sites resulting from reduced titration of O3 by NO. The relaxation of the lockdown measures beginning in May resulted in close to expected NO2 concentrations in the urban background, and to significant increases in PM10 in comparison to expected concentrations at both regional and urban background sites.

Jean-Philippe Putaud et al.

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Jean-Philippe Putaud et al.

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Latest update: 19 Oct 2020
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Short summary
To determine the impact of the COVID lockdown on air quality in northern Italy, measurements of atmospheric pollutants (NO2, PM10, O3, NO, SO2) were compared to the output of a model ignoring the lockdown. We found that NO2 decreased on average by −30 % to −40 %. Unlike NO2, PM10 was not significantly affected, due to the compensation of decreased emissions from traffic by increased emissions from domestic heating and/or from changes in atmospheric chemistry leading to increased O3 levels.
To determine the impact of the COVID lockdown on air quality in northern Italy, measurements of...
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