4.—(1) This Part applies in respect of the following pollutants—
(a)Group A pollutants;
(b)Group B pollutants; and
(c)ozone.
(2) The National Assembly must ensure that all measures taken under Chapter 2 or 3 of this Part—
(a)take into account an integrated approach to the protection of air, water and soil; and
(b)have no significant negative effects on—
(i)any other member State, or
(ii)any other part of the United Kingdom.
5.—(1) The National Assembly must, for the purposes of this Part, divide the territory of Wales into zones.
(2) A zone is to be classified as an agglomeration for the purposes of this Part where—
(a)it comprises a population in excess of 250,000 inhabitants; or
(b)in any other case, it has a population density per km2 for which the National Assembly considers that such a classification is justified.
(3) The National Assembly may establish different zones for different pollutants where it considers it appropriate.
6.—(1) Subject to paragraphs (2) to (4), the following air quality standards specified in Schedule 1 are required to be attained within each zone—
(a)for Group A pollutants, the limit values set out in Part 1 of that Schedule;
(b)for Group B pollutants, the target values set out in Part 3 of that Schedule; and
(c)for ozone, the target values and long-term objectives set out in Part 4 of that Schedule.
(2) The attainment date for a limit or target value is—
(a)the attainment date specified for the relevant pollutant in Schedule 1; or
(b)where no attainment date is specified, the date on which these Regulations come into force.
(3) The long-term objectives are to be attained in the long term, to the extent these objectives are achievable through the measures required by regulation 7(3)(b).
(4) In the case of benzene and nitrogen dioxide, the margins of tolerance set out in Part 2 of Schedule 1 apply within the periods specified.