# The Air Quality Limit Values (Wales) Regulations 2002, Paragraph 2.1: Limit values for nitrogen dioxide and oxides of nitrogen

Extent: E+W

Averaging period
Limit value
Margin of tolerance
Date by which limit value is to be met
1.Hourly limit value for the protection of human health
1 hour
200μg/m3 NO2, not to be exceeded more than 18 times a calendar year
70μg/m3 on 1st January 2003, reducing on 1st January of each following year by equal annual amounts to reach 0μg/m3 by 1st January 2010
1st January 2010
2.Annual limit value for the protection of human health
Calendar year
40μg/m3 NO2
14μg/m3 on 1st January 2003, reducing on 1st January of each following year by equal annual amounts to reach 0μg/m3 by 1st January 2010
1st January 2010
3.Annual limit value for the protection of vegetation
Calendar year
30μg/m3 NOx
None

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Source: https://www.legislation.gov.uk/wsi/2002/3183/schedule/1/part/II/paragraph/2n1 (the official version)
Page: https://openlegislation.uk/air-quality-limit-values-wales-regulations-2002/schedule-1/part-II/paragraph-2n1
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.