Air Quality Index

The Air Quality Index (AQI) is an indicator of pollutant levels and can therefore be considered as a measure of the effects of air pollution on human health.

The forecasts are updated daily and are based on simulations using the WRF-Chem model. The AQI calculation incorporates (predicted) concentrations of various pollutants (e.g. ozone, nitrogen dioxide, particulate matter).

Air pollution levels are divided into six categories ranging from ‘very good’ to ‘extremely poor’. These levels correspond to the Air Quality Index as published by the European Environment Agency (EEA). These categories relate to potential health impacts, especially for at-risk groups. 

Suggested outdoor activity behaviours

For each level of the Air Quality Index (AQI), the European Environment Agency has defined behavioural guidelines for outdoor activities. In addition to general recommendations for the population, there are also specific guidelines tailored to at-risk groups (adults and children with respiratory issues, as well as adults with heart conditions).

AQI: ‘good’ and ‘fair’

  • General population: Enjoy your usual outdoor activities.
  • Sensitive populations: Enjoy your usual outdoor activities.

AQI: ‘moderate’

  • General population: Enjoy your usual outdoor activities.
  • Sensitive populations: Consider reducing intense outdoor activities, if you experience symptoms.

AQI: ‘poor’

  • General population: Consider reducing intense activities outdoors, if you experience symptoms such as sore eyes, a cough or sore throat.
  • Sensitive populations: Consider reducing physical activities, particularly outdoors, especially if you experience symptoms.

AQI: ‘very poor’

  • General population: Consider reducing intense activities outdoors, if you experience symptoms such as sore eyes, a cough or sore throat.
  • Sensitive populations: Reduce physical activities, particularly outdoors, especially if you experience symptoms.

AQI: ‘extremely poor’

  • General population: Reduce physical activities outdoors.
  • Sensitive populations: Avoid physical activities outdoors.