• Emissions modelling - We computed daily emission adjustment factors by compiling, analysing and combining activity data observed in almost real-time from different sources, together with weather information and artificial intelligence techniques. The factors were combined with the CAMS European emission inventory to derive the daily emission changes per pollutant, country and sector (e.g. road transport, energy). The computed changes in emissions performed well against reported changes in the stringency of the lockdown measures.

• Data visualisation - Our team designed several compelling and easy-to-interpret visuals (including for use in the CAMS website and communication campaigns.

As a result of COVID-19 lockdowns, a sudden drop was seen in air pollutant and greenhouse gas emissions across Europe. Ground-based observations, satellite data and advanced numerical models are used to track the changes in air quality and pollutant concentrations. Improved emission modelling data are required to understand better the impact of the COVID-19 crisis on air pollution and monitor the return to business-as-usual levels.