# Directive 2008/50/EC of the European Parliament and of the Council of 21 May 2008 on ambient air quality and cleaner air for Europe, Division A: Alert thresholds for pollutants other than ozone

Extent: E+W+S+N.I.

To be measured over three consecutive hours at locations representative of air quality over at least 100 km2 or an entire zone or agglomeration, whichever is the smaller.
Pollutant
Alert threshold
Sulphur dioxide
500 μg/m3
Nitrogen dioxide
400 μg/m3

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Source: https://www.legislation.gov.uk/eudr/2008/50/annex/XII/division/A (the official version)
Page: https://openlegislation.uk/eu-directive-2008-50/annex-XII/division-A
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.