Briefly, depending on the predominant emission sources, stations are classified as follows:

  • traffic stations: located in close proximity to a single major road;
  • industrial stations: located in close proximity to an industrial area or an industrial source;
  • background stations: where pollution levels are representative of the average exposure of the general population or vegetation.

Depending on the distribution/density of building, the area surrounding the station is classified as follows:

  • urban: continuously built-up urban area;
  • suburban: largely built-up urban area;
  • rural: all other areas.

For most of the pollutants, monitoring stations have to fulfil the criterion of reporting more than 75 % of valid data out of all the possible data in a year to be included in EEA´s assessments. The Ambient Air Quality Directives set, for compliance purposes, the objective of a minimum data capture of 90 % for monitoring stations, but, for assessment purposes, a coverage of 75 % allows more stations to be taken into account without a significant increase in monitoring uncertainties. For benzene, the required amount of valid data for the analysis is 50 %. For toxic metals (As, Cd, Ni, Pb) and BaP, it is 14 % (according to the air quality objectives for indicative measurements).

Measurement data are rounded following the general recommendations under Commission Implementing Decision 2011/850/EU. The number of considered decimals are indicated in the legend of the corresponding maps.

The assessments, in the cases of PM and SO2, do not account for the fact that the Ambient Air Quality Directive 2008/50/EC provides Member States with the possibility of subtracting contributions to the measured concentrations from natural sources and winter road sanding/salting under specific circumstances.


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Filed under: monitoring stations
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