These Regulations are made in exercise of the powers in section 2(2) of the European Communities Act 1972 (c. 68) and section 8 of, and paragraph 21 of Schedule 7 to, the European Union (Withdrawal) Act 2018 (c. 16).
Link: The Air Quality (Amendment of Domestic Regulations) (EU Exit) Regulations 2019
Source: Legislation .gov.uk