The Air Quality Standards (Wales) Regulations 2010

Duty in relation to limit values

13.—(1) Subject to paragraph (2), the Welsh Ministers must ensure that levels of sulphur dioxide, nitrogen dioxide, benzene, carbon monoxide, lead, PM₁₀ and PM_2·5 do not exceed the limit values set out in Schedule 1 in any zone.

(2) Where the date for achieving the limit values for nitrogen dioxide is postponed in any zone in accordance with regulation 15(2), the Welsh Ministers must ensure that the level of nitrogen dioxide in that zone does not exceed the limit value for that pollutant set out in Schedule 1 by more than 50%.

(3) In zones where the level of any pollutant mentioned in paragraph (1) is below the limit value set out in Schedule 1 for that pollutant, the Welsh Ministers must ensure that the level of that pollutant is maintained below that limit value and must endeavour to maintain the best ambient air quality compatible with sustainable development.

(4) Where the Commission has been informed, in accordance with Article 20 of Directive 2008/50/EC, that the exceedance of any limit value mentioned in paragraph (1) is attributable to natural sources, that exceedance is not to be regarded as an exceedance for the purposes of these Regulations.