# The Air Quality Limit Values Regulations 2001, Part II: Minimum number of sampling points for fixed measurements to assess compliance with limit values for the protection of ecosystems or vegetation in zones other than agglomerations


If maximum concentrations exceed the upper assessment threshold
If maximum concentrations are between the upper and lower assessment thresholds
In island zones the number of sampling points for fixed measurement should be calculated taking into account the likely distribution patterns of ambient-air pollution and the potential exposure of ecosystems or vegetation.
1 station every 20,000 km2
1 station every 40,000 km2

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Source: https://www.legislation.gov.uk/uksi/2001/2315/schedule/4/part/II (the official version)
Page: https://openlegislation.uk/air-quality-limit-values-regulations-2001/schedule-4/part-II
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.