# The Air Quality Standards (Wales) Regulations 2007, Paragraph 4


Nature and assessment of pollution—
(a) concentrations observed over previous years (before the implementation of the improvement measures);
(b) concentrations measured since the beginning of the project; and
(c) techniques used for the assessment.

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Source: https://www.legislation.gov.uk/wsi/2007/717/schedule/2/paragraph/4 (the official version)
Page: https://openlegislation.uk/air-quality-standards-wales-regulations-2007/schedule-2/paragraph-4
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.