8.—(1) This regulation applies in respect of each zone in which prior to the attainment date—
(a)concentrations of benzene or nitrogen dioxide exceed a limit value plus the applicable margin of tolerance; or
(b)concentrations of ozone exceed a target value.
(2) Where paragraph (1)(a) applies, the Secretary of State shall prepare and implement an improvement plan for the pollutant in question or, where concentrations of both pollutants exceed the level referred to, a single improvement plan for both pollutants.
(3) Where paragraph (1)(b) applies, the Secretary of State shall prepare and implement an improvement plan in respect of ozone unless he considers that the target value would not be attainable through proportionate measures.
(4) An improvement plan shall include the information specified in Schedule 2.
(5) Where the Secretary of State is required to prepare and implement an improvement plan under both paragraphs (2) and (3) he shall, where he considers it appropriate, prepare and implement an integrated improvement plan covering all of the pollutants concerned.
(6) An improvement plan may comprise either a plan or a programme which, in either case, shall have the objective of attaining—
(a)the limit value, by the attainment date; or
(b)the target value, by 2010.