# The Air Quality Limit Values (Wales) Regulations 2002, Paragraph

Extent: E+W

The maximum daily 8-hour mean concentration shall be selected by examining 8-hour running averages, calculated from hourly data and updated each hour. Each 8-hour average so calculated shall be assigned to the day on which it ends, i.e. the first calculation period for any one day shall be the period from 17:00 on the previous day to 01:00 on that day; the last calculation period for any one day shall be the period from 16:00 to 24:00 on that day.

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Source: https://www.legislation.gov.uk/wsi/2002/3183/schedule/1/part/VI/paragraph/wrapper2n1 (the official version)
Page: https://openlegislation.uk/air-quality-limit-values-wales-regulations-2002/schedule-1/part-VI/paragraph-wrapper2n1
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.