Nitrogen dioxide concentrations observed over major European cities

This graph shows the averaged nitrogen dioxide concentrations over five major European cities. The upper panel shows concentrations (using a 14-day moving average) in 2019 compared to 2020 using data from the Copernicus Sentinel-5P satellite, while the lower panel shows in situ observations.

The shades of grey denote the lockdown periods in 2020, moving progressively from strict (dark grey) to loose (light grey) measures. The percentages shown in red represent the column reduction in 2020 compared to 2019 over the same period.

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