# The Air Quality Standards (Wales) Regulations 2010, Paragraph

Extent: E+W

Sulphur dioxide
Averaging period
Critical level
Calendar year and winter (1 October to 31 March)
20 μg/m3
Oxides of nitrogen
Averaging period
Critical level
Calendar year
30 μg/m3 NOx

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Source: https://www.legislation.gov.uk/wsi/2010/1433/schedule/5/paragraph/wrapper5n1 (the official version)
Page: https://openlegislation.uk/air-quality-standards-wales-regulations-2010/schedule-5/paragraph-wrapper5n1
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.