# The Air Quality Limit Values (Wales) Regulations 2002, Paragraph 1.1: Limit values for sulphur dioxide

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
350μg/m3, not to be exceeded more than 24 times a calendar year
60μg/m3 on 1st January 2003, reducing on 1st January of each following year by equal annual amounts to reach 0μg/m3 by 1st January 2005
1st January 2005
2.Daily limit value for the protection of human health
24 hours
125μg/m3, not to be exceeded more than 3 times a calendar year
None
1st January 2005
3.Limit value for the protection of ecosystems
Calendar year and winter (1st October to 31st March)
20μg/m3
None

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