Road travel restrictions implemented by governments in 2020 due to the pandemic helped to reduce NO2 concentrations and the number of deaths. This is revealed in a study by the Copernicus Atmospheric Monitoring Service and several European centres.

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Reduction in nitrogen dioxide (NO2) concentrations in 47 European cities with data from 1 February to 31 July 2020. / LSHTM/CAMS

A team of European scientists has assessed the relationship between containment measures taken between 1 February and 31 July 2020 and the decrease in the levels of four pollutants (nitrogen dioxide or NO2, ozone, PM2.5 and PM10) in 47 major European cities, and estimated the number of deaths avoided in those cities during that period.

The main conclusion of the research is that there were significantly different results depending on the different interventions. For example, school and workplace closures, cancellation of public events and movement restrictions had the greatest effect on reducing NO2 levels, as people were unable to travel to their usual places.

The results show that Spanish, French and Italian cities had the largest decreases in nitrogen dioxide of between 50% and 60% on the dates analysed and that nitrogen dioxide levels fell considerably across Europe. The decrease in other pollutants was less marked.

The authors believe this is because about half of NO2 emissions are generated by road transport, which was the sector most affected by the restrictions, a type of travel that contributes much less to the total emissions of the other pollutants studied. In fact, the restrictions on domestic and international travel had little impact on overall local air pollution levels.

Estimating changes in mortality
The study quantified changes in premature deaths resulting from short-term changes in pollution in cities. By analysing changes in daily concentrations of the compounds, together with an assessment of population exposure, the scientists estimated that a total of more than 800 deaths were prevented due to improved air quality resulting from government measures to limit the spread of the coronavirus.

The research used land surface data from CAMS using regional air quality models to compare the concentrations of the main air pollutants under two pollutant emission scenarios: one with business-as-usual conditions and the other with estimated emissions from government measures during the first containment, which was different for each country, each day and each sector of activity (road traffic, industry, etc.).

Further decrease in NO2
This assessed the individual policy interventions in each city and their impact on reducing pollution levels. Although there were different effects, as expected, they observed a strong decrease in NO2 and, to a lesser extent, in fine particulate matter PM2.5 and PM10 in the areas where stricter confinements were applied.

“The government policies that were decided in the spring and early summer of 2020 gave us the unique opportunity to study a real scenario with lower levels of air pollution,” says Rochelle Schneider, LSHTM researcher and first author of the study, who stresses: “This and similar studies can help get the message across that we definitely need to improve urban air quality for both human health and the environment.

Vincent-Henri Peuch, director of the Copernicus Atmospheric Monitoring Service (CAMS), adds: “The findings are extremely important because they consolidate the quantitative evidence that government measures related to covid had a direct effect on air pollution levels in Europe, especially with regard to NO2.

“Beyond the analysis of mortality in the first months of the pandemic, this study could help determine future policy,” he concludes, “because it clearly shows the benefits of reducing pollution in our cities and the effectiveness of certain measures.

Reference:

Rochelle Schneider et al. “Differential impact of government lockdown policies on reducing air pollution levels and related mortality in Europe”. Scientific Reports, 2022.