# 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 B: Determination of exceedances of upper and lower assessment thresholds

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

Exceedances of upper and lower assessment thresholds shall be determined on the basis of concentrations during the previous five years where sufficient data are available. An assessment threshold shall be deemed to have been exceeded if it has been exceeded during at least three separate years out of those previous five years.
Where fewer than five years’ data are available, Member States may combine measurement campaigns of short duration during the period of the year and at locations likely to be typical of the highest pollution levels with results obtained from information from emission inventories and modelling to determine exceedances of the upper and lower assessment thresholds.

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