Air quality and COVID-19

Impacts on air pollution

Data from EEA member countries show how concentrations of nitrogen dioxide (NO₂) — a pollutant mainly emitted by road transport — have decreased in many European cities where lockdown measures have been implemented.

Although a decrease in concentrations of fine particulate matter (PM_2.5) may also be expected, a consistent reduction cannot yet be seen across European cities. This is likely due to the fact that the main sources of this pollutant are more varied, including at European level the combustion of fuel for the heating of residential, commercial and institutional buildings, industrial activities and road traffic. A significant fraction of particulate matter is also formed in the atmosphere from reactions of other air pollutants, including ammonia — a pollutant typically emitted from the application of agricultural fertilisers at this time of year.

Other factors, such as weather conditions, may also significantly contribute to the reductions seen in pollutant concentrations. Conversely, changes in meteorology can also lead to increased air pollution, and coupled with the often non-linear relationships between changes in emissions and changes in concentrations, also explain why lower air pollution may not occur at all locations.

Data source

About the viewer

The EEA’s data are measured hourly or daily, on the ground, at about 3 000 monitoring stations across European countries. The viewer shows those cities according to their definition in Eurostat’s city statistics database (former Urban Audit).

All types of air quality monitoring stations within a city are considered. Stations can be filtered to select only ‘traffic stations’ that are close to roads. Users can also select different pollutants, countries and cities.

The viewer shows weekly and monthly averages for each city, in two different tabs. To produce the weekly values, a daily mean is first calculated from the hourly values for each station reported by countries to the EEA. The daily means for all stations in a city are then averaged together to produce the weekly average for that city. The same methodology is followed for the monthly values.

The viewer also shows the percentage change in pollutant concentrations in a city compared to concentrations in the previous week or month. Weekly averaged values are displayed to show the effect of the lockdown measures on air quality in a short period. As noted above, other factors, such as weather conditions, will also contribute to the observed changes in air pollution.

There are no legal standards for these pollutants on a weekly or monthly basis (for NO₂ the EU standards are based on hourly and annual averages, and for PM, on daily and annual averages). The hourly ‘near-real time’ air quality measurements are also not formally verified by countries and are considered as provisional data. Gaps in the table and in the viewer represent weeks or months where data was not reported to the EEA.

The weeks are labelled by their starting day in the graph and tables and by their number in the filter. The values for the current month correspond to the average of the days received up to the end of the previous week.

The viewer is updated every Monday at 8:30 a.m.