# Air Quality Regulations (Northern Ireland) 2003, Paragraph 6: Interpretation

Extent: N.I.
Status: prospective

A 24-hour mean is a mean calculated every 24 hours. The 24 hour mean for a particular substance at a particular location for a particular 24 hour period is the level at which that substance is recorded as being present in the air at that location on the basis of a continuous sample of air taken throughout the period.

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Source: https://www.legislation.gov.uk/nisr/2003/342/schedule/paragraph/6 (the official version)
Page: https://openlegislation.uk/air-quality-regulations-northern-ireland-2003/schedule/paragraph-6
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.