Air quality index (long term)

The ambient air quality index (AQ) per municipality is based on the high-resolution mapping of the multi-annual averages of 3 types of pollutants (NO2, PM10 and PM2.5) calculated using "[\2](\1)". The scale of this index is representative of the long-term health impact of pollution. The long-term impact turns out to be chronic and therefore more important on health than a short-term impact. The annual average air quality index shall be expressed on a basis similar to "[\2](\1)", i.e. a scale from 1 to 10, 1 corresponding to excellent air quality and 10 to appalling quality. This scale is adapted to the values recommended in 2021 by the World Health Organization (WHO), which are stricter than before. Before 2024, an ambient air quality indicator comparing municipalities with the Walloon average was published on Walstat. Thanks to new measurements, modelling and methods, this indicator is replaced by this new index, expressed on the BelAQI scale, which is better suited to taking long-term health risks into account.