One year after the first COVID-19 lockdown in many parts of the UNECE region, scientists and experts are studying the effects of lockdown measures on air quality. A study from Germany showed that while levels of nitrogen oxides (NO2) measured at urban stations decreased during the lockdown in spring 2020 as a result of a significant decline in road traffic, these effects seem to be rather short-term and affect the annual mean NO2 values very little. The short-term effects of the lockdown on NO2 concentrations vary greatly between different countries, cities and measurement stations, according to another study, with the largest NO2 reductions in Spain, France, Italy, Great Britain and Portugal and the smallest in eastern countries (Poland and Hungary).
While less NO2 in the air we breathe reduces risks to our health, concentrations of particulate matter (PM2.5, PM10), another pollutant that can cause severe health impacts, did not decrease in a similar way. In fact, the German study shows that the lockdown in spring 2020 had hardly any effect on concentrations of particulate matter. The reason is that concentrations of particle pollution undergo even more complex chemical transformations in the atmosphere than other pollutants and the sources are much more varied. Heating of residential and other buildings and the application of fertilizers in agriculture are the main sources of particle pollution – sources that have not been affected as much by the lockdown. The picture looks quite different for the second lockdown in Germany on New Year’s Eve and New Year’s Day. Data shows that concentrations of particles in the air were much lower than in previous years as private fireworks, which normally cause a peak in particulate pollution at the turn of the year, were prohibited.
Scientists and other air pollution experts discussed these short-term effects of the COVID-19 lockdowns on air quality at the 50th meeting of the Task Force on Integrated Assessment Modelling under the UNECE Convention on Long-range Transboundary Air Pollutants (Air Convention) (21-23 April 2021). Experts concluded that further studies need to be carried out to complement the results so far, specifically as regards the long-term effects of the lockdowns on air quality in the UNECE region.