# The Air Quality (Wales) Regulations 2000, Paragraph 2

Extent: E+W

(1) A maximum daily running 8 hour mean is calculated on a daily basis. The maximum daily running 8 hour mean for a particular substance at a particular location for a particular day is the maximum of the running 8 hour means ending during that day.
(2) For the purpose of sub-paragraph (1), a “running 8 hour mean” is a mean which is calculated on an hourly basis, yielding one running 8 hour mean per hour. The running 8 hour mean for the relevant substance at the relevant location for a particular hour is the mean of the hourly means for the substance at the location for that hour and the preceding 7 hours.

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Source: https://www.legislation.gov.uk/wsi/2000/1940/schedule/paragraph/2 (the official version)
Page: https://openlegislation.uk/air-quality-wales-regulations-2000/schedule/paragraph-2
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.