# The Air Quality Standards (Wales) Regulations 2007, Paragraph 7: Benzene and carbon monoxide


The uncertainty (on a 95% confidence interval) of the assessment methods must be evaluated in accordance with the “Guide to the Expression of Uncertainty of Measurements” (ISO 1993) or the methodology of ISO 5725:1994. The percentages for uncertainty in the above table are given for individual measurements averaged over the period considered by the limit value, for a 95% confidence interval. The uncertainty for the fixed measurements should be interpreted as being applicable in the region of the appropriate limit value.

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Source: https://www.legislation.gov.uk/wsi/2007/717/schedule/8/paragraph/7 (the official version)
Page: https://openlegislation.uk/air-quality-standards-wales-regulations-2007/schedule-8/paragraph-7
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.