# 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: Target values

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

Compliance with target values will be assessed as of this date. That is, 2010 will be the first year the data for which is used in calculating compliance over the following three or five years, as appropriate.
The maximum daily eight-hour mean concentration shall be selected by examining eight-hour running averages, calculated from hourly data and updated each hour. Each eight -hour average so calculated shall be assigned to the day on which it ends. i.e. the first calculation period for any one day will be the period from 17:00 on the previous day to 01:00 on that day; the last calculation period for any one day will be the period from 16:00 to 24:00 on the day.
If the three or five year averages cannot be determined on the basis of a full and consecutive set of annual data, the minimum annual data required for checking compliance with the target values will be as follows:
for the target value for the protection of human health: valid data for one year,
for the target value for the protection of vegetation: valid data for three years.
Objective
Averaging period
Target value
Date by which target value should be met
Protection of human health
Maximum daily eight-hour mean
120 μg/m3 not to be exceeded on more than 25 days per calendar year averaged over three years
1.1.2010
Protection of vegetation
May to July
AOT40 (calculated from 1 h values)
18 000 μg/m3 · h averaged over five years
1.1.2010

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