EU air quality legislation requires EU Member States to report on air quality zones designated under the Ambient Air Quality Directives (Directive 2008/50/EC and Directive 2004/107/EC). Member States need to make certain information on these zones and agglomerations available. More details on this information can be found in Article 6 of Commission implementing Decision 2011/850/EU.
Consult country maps of air quality zones (as reported for 2014) and the relevant monitoring stations that have reported data to the European Commission (2013 to 2014). The EU comprised 28 Member States at this time.
More recent data is available via the European Air Quality Portal.