# The Air Quality Standards (Wales) Regulations 2007, Part 2: Margins of tolerance for benzene and nitrogen dioxide


Start of period during which the margin applies
End of period during which the margin applies
Benzene
Nitrogen dioxide (hourly limit value for the protection of human health)
Nitrogen dioxide (annual limit value for the protection of human health)
Coming into force of these Regulations
31 December 2007
3 μg/m3
30 μg/m3
6 μg/m3
1 January 2008
31 December 2008
2 μg/m3
20 μg/m3
4 μg/m3
1 January 2009
31 December 2009
1 μg/m3
10 μg/m3
2 μg/m3

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Source: https://www.legislation.gov.uk/wsi/2007/717/schedule/1/part/2 (the official version)
Page: https://openlegislation.uk/air-quality-standards-wales-regulations-2007/schedule-1/part-2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.