Europe is currently an epicentre of the Covid-19 pandemic. The corresponding lockdown measures are unprecedented and compel much of the population to stay in their homes, slowing down the economy and reducing traffic. This affects air quality, which should improve due to the reduction of emissions of atmospheric pollutants across almost all of Europe. Quantification of air quality impact is, however, challenging because the observed concentrations of air pollutants strongly depend on meteorological parameters such as wind and dispersion. We explore the situation in Switzerland with ambient monitoring data from the National Air Pollution Monitoring Network (NABEL) and statistical tools to predict the expected air quality independently of Covid-19-related measures. The observations and the data analysis are preliminary, and research is ongoing. The results will be continuously updated d revised and can be found here.