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

Extent: E+W

Sulphur dioxide
Averaging period
Limit value
One hour
350 μg/m3, not to be exceeded more than 24 times a calendar year
One day
125 μg/m3, not to be exceeded more than 3 times a calendar year
Nitrogen dioxide
Averaging period
Limit value
One hour
200 μg/m3, not to be exceeded more than 18 times a calendar year
Calendar year
40 μg/m3
Benzene
Averaging period
Limit value
Calendar year
5 μg/m3
Carbon monoxide
Averaging period
Limit value
Maximum daily eight hour mean
10 mg/m3
Lead
Averaging period
Limit value
Calendar year
0.5 μg/m3
PM10
Averaging period
Limit value
One day
50 μg/m3, not to be exceeded more than 35 times a calendar year
Calendar year
40 μg/m3
PM2·5
Averaging period
Limit value
Margin of tolerance
Date by which limit value is to be met
Calendar year
25 μg/m3
20% on 11 June 2008, decreasing on the next 1 January and every 12 months thereafter by equal annual percentages to reach 0% by 1 January 2015
1 January 2015

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Source: https://www.legislation.gov.uk/wsi/2010/1433/schedule/1/paragraph/wrapper1n1 (the official version)
Page: https://openlegislation.uk/air-quality-standards-wales-regulations-2010/schedule-1/paragraph-wrapper1n1
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.