A period of time where the concentration of a pollutant is greater than, or equal to, the appropriate air quality criteria. For air quality standards an exceedence is a concentration greater than the standard value. For air quality bands an exceedence is a concentration greater than, or equal to, the upper band threshold.
This website is prepared and hosted by AEA, on behalf of the UK Department for Environment, Food & Rural Affairs and the Devolved Administrations