Annex - Methodological approaches

This report focuses on air pollutants deemed most harmful to human health.

The concentrations are obtained from monitoring station measurements and are officially reported to the EEA by its members and other collaborating countries.

The classification of the monitoring stations and the criteria used to determine their inclusion in the analysis are described here. Stations which do not fulfil the data coverage criteria to be included in this report can be still found in the annual air quality statistics table. In some cases, countries have used measurements from these stations to officially report exceedances.

The number of countries that submitted data and the number of monitoring stations with the minimum data coverage required vary for each pollutant. Information relevant to this is specified in each section of the report on specific pollutants. When countries are referred to as having reported data above certain standards, it means that at least one of the stations in that country had levels surpassing the standard.

Data for 2024 and 2025 were extracted from the EEA’s reporting system on 9 February 2026.

The analysis for 2024 is based on officially validated data reported by countries. The analysis for 2025 is based on provisional up-to-date (UTD) data. It may change once fully validated data are received by the EEA and more stations and the countries that did not submit UTD data are considered. Validated data for 2025 will only be available later in 2026 and will be presented in the relevant EEA viewers and products.

Percentages of stations in a specific year refer to the total reporting stations in that year. The 2024 and 2025 numbers of reporting stations are sometimes different and the number of reporting stations for different pollutant aggregations can also vary.

Additional information and further analysis are available in the two Eionet status reports: ETC HE 2026/1 ((ETC-HE, 2026a) and ETC HE 2026/2  (ETC-HE, 2026b) prepared by the ETC HE.

Further information on the concentrations of air pollutants, including those for previous years, can be found at the EEA’s statistics viewer. Data can be downloaded here.

Apart from the measurements from monitoring stations, some countries also reported official 2024 data from modelling applications; these are available from the air quality modelling viewer. The results from these modelling applications have been included in this analysis where they implied concentrations above the EU standards.