# The Air Quality Standards (Wales) Regulations 2007, Part 1: Assessment thresholds for Group A pollutants


Annual average
Upper assessment threshold
70% of limit value (3.5 μg/m3)
Lower assessment threshold
40% of limit value (2 μg/m3)

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Source: https://www.legislation.gov.uk/wsi/2007/717/schedule/4/part/1 (the official version)
Page: https://openlegislation.uk/air-quality-standards-wales-regulations-2007/schedule-4/part-1
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.