# The Air Quality Limit Values (Scotland) Regulations 2001, Paragraph 4: Nature and assessment of pollution


– concentrations observed over previous years (before the implementation of the improvement measures)
– concentrations measured since the beginning of the project
– techniques used for the assessment.

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Source: https://www.legislation.gov.uk/ssi/2001/224/schedule/7/paragraph/4 (the official version)
Page: https://openlegislation.uk/air-quality-limit-values-scotland-regulations-2001/schedule-7/paragraph-4
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.