Quantifying the improvements in air quality in the Netherlands from the corona lockdown

Abstract:

The lockdown measures in Europe in response to the corona SARS-CoV-2 virus outbreak, that causes the COVID-19 disease, in 2020 have significantly reduced traffic volumes and industrial activities. As a direct result, emissions of various air pollutants from these sectors have also been reduced, although the magnitude of the reductions has not been assessed yet. Satellite observations of nitrogen dioxide (NO₂) of China, Northern Italy and the USA have shown reductions in column densities in the spring of 2020 which are attributed to the corona lockdown measures in these countries. Quantifying the effects of the lockdown measures in term of reductions in concentrations of, e.g., NO₂ and particulate matter (PM₁₀, PM_2.5) requires a separation of these effects with those from natural meteorological variability. The Netherlands experienced unusual meteorological conditions in spring 2020 starting about at the same time as the corona lockdown measures. Two methods are employed to quantify the effects of the lockdown measures on the concentrations of NO₂, PM₁₀, and PM_2.5, and ozone in the Netherlands. First, we report on the observed trends in surface concentrations from various measurement stations in the Netherlands from January till May 2020 and use a Random Forest method to estimate what the concentrations in spring 2020 would have been without the lockdown measures. Second, we performed simulations with the EMEP4NL atmospheric chemistry transport model using a reference scenario and a scenario with estimates of emissions reductions to disentangle the effects of the corona lockdown measures on concentrations from those coming from the meteorological variability. Combining the analyses of the measured trends with the model simulations we estimate the magnitude of the lockdown measures on the concentrations in the Netherlands.