# The Air Quality Limit Values Regulations 2001, Paragraph 2.1: Limit values for nitrogen dioxide and oxides of nitrogen


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
200 μg/m3 NO2, not to be exceeded more than 18 times a calendar year
90 μg/m3 on 19th July 2001, reducing on 1st January of each following year by equal annual amounts to reach 0 μg/m3 by 1st January 2010
1st January 2010
2 Annual limit value for the protection of human health
Calendar year
40 μg/m3 NO2
18 μg/m3 on 19th July 2001, reducing on 1st January of each following year by equal annual amounts to reach 0 μg/m3 by 1st January 2010
1st January 2010
3 Annual limit value for the protection of vegetation
Calendar year
30 μg/m3 NOx
None
19th July 2001

---
Source: https://www.legislation.gov.uk/uksi/2001/2315/schedule/1/paragraph/2.1 (the official version)
Page: https://openlegislation.uk/air-quality-limit-values-regulations-2001/schedule-1/paragraph-2.1
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.