# The Air Quality (England) Regulations 2000, Paragraph 5: Interpretation


An hourly mean is a mean calculated every hour. The hourly mean for a particular substance at a particular location for a particular hour is the mean of the levels recorded, at a frequency of not less than once every 10 seconds, for that substance at that location during that hour.

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Source: https://www.legislation.gov.uk/ukdsi/2000/0110987640/schedule/paragraph/5 (the official version)
Page: https://openlegislation.uk/draft-air-quality-england-regulations-2000/schedule/paragraph-5
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.