Air quality: EU rules for modelling and for determining the spatial representativeness of sampling points — applicable from 30 June 2028
Commission Implementing Decision (EU) 2026/1208, published on 10 June 2026, sets out under the new Ambient Air Quality Directive (EU) 2024/2881 minimum requirements for modelling, its quality assurance and validation, and for determining the spatial representativeness areas of sampling points. The decision applies from 30 June 2028.
- A sampling point’s representativeness area covers locations whose concentrations fall within a range around the point’s annual mean: ±15 % of that value or the minimum allowed deviation limit, whichever is greater — e.g. ±2.0 µg/m³ for PM10, NO2, O3 and SO2, ±1.0 µg/m³ for PM2.5, ±0.34 µg/m³ for benzene, ±0.1 ng/m³ for benzo(a)pyrene and ±0.5 ng/m³ for cadmium.
- Areas are determined by fixed or indicative measurements (evenly spread over the year, for ozone over April to September), by modelling or by both; the map is drawn up using data from one year within the last five years and reviewed at least after each review under point D.9 of Annex IV to the directive and whenever the monitoring network changes or sources or meteorology change significantly. The directive requires information on the representativeness of all sampling points to be published at least once every five years.
- Modelling must reproduce the averaging periods of the limit and target values, and input data — emissions, meteorology, background concentrations — undergo quality control before each modelling run. Models combining measurements and calculations are validated, among other ways, with a “leave-one-out” method: each station in turn is left out of the data fusion and the result is compared with it.
- Modelled concentrations are used for assessment against limit values where both the model and the measurement at the sampling point show an exceedance. Where the model indicates a concentration above the assessment threshold but below the limit or target value at a location outside the representativeness area of a fixed station, a Member State may instead set up an additional measurement — fixed within two calendar years or indicative within one year — lasting at least one year.