Limit value for lead in the air
4.—(1) The Secretary of State shall take any necessary measures to ensure that the mean annual value for the concentration of lead in the air, measured in accordance with regulation 5, does not exceed the limit value of 2 micrograms of lead per cubic metre expressed as an annual mean concentration.
(2) Paragraph (1) shall not apply within a circular area one mile in radius centred on National Grid reference point 399350E 297750N (being an area near Walsall, West Midlands) until 9th December 1989.