17.—(1) The Secretary of State must ensure that levels of sulphur dioxide, nitrogen dioxide, benzene, carbon monoxide, lead and particulate matter do not exceed the limit values set out in Schedule 2.
(2) In zones where levels of the pollutants mentioned in paragraph (1) are below the limit values set out in Schedule 2, the Secretary of State must ensure that levels are maintained below those limit values and must endeavour to maintain the best ambient air quality compatible with sustainable development.
18.—(1) The Secretary of State must ensure that all necessary measures not entailing disproportionate costs are taken to ensure that concentrations of PM2.5, ozone, arsenic, cadmium, nickel and benzo(a)pyrene do not exceed the target values in Schedule 3.
(2) The Secretary of State must draw up a list of all zones where the target values for arsenic, cadmium, nickel or benzo(a)pyrene are met and in relation to those zones, must maintain the levels of those pollutants below those target values and must endeavour to achieve the best ambient air quality compatible with sustainable development.
(3) The Secretary of State must draw up a list of all zones where the target value for arsenic, cadmium, nickel or benzo(a)pyrene is exceeded, and in relation to those zones, must identify the areas where those values are exceeded and the relevant sources of pollutants.
(4) In relation to the zones to which paragraph (3) applies, the measures in paragraph (1) must be directed at the predominant sources of emission which have been identified, and where applicable will entail the application of best available techniques in accordance with Directive 2008/1/EC of the European Parliament and of the Council concerning integrated pollution prevention and control(1).
19.—(1) Limit values and target values—
(a)apply from the date specified for each limit value or target value concerned; or
(b)apply when these Regulations come into force, if no date is specified.
20.—(1) The Secretary of State must ensure that all necessary measures not entailing disproportionate cost are taken to attain the long-term objectives for ozone set out in Schedule 4.
(2) In zones where the long-term objectives for ozone have been attained, the Secretary of State must, insofar as factors including meteorological conditions and the transboundary nature of ozone pollution permit—
(a)ensure that they continue to be met;
(b)maintain the best ambient air quality compatible with sustainable development;
(c)maintain a high level of protection for the environment and human health.
21. Where any of the information or alert thresholds in Schedule 5 are exceeded the Secretary of State must inform the public by means of radio, television, newspapers or the internet.
22. The Secretary of State must ensure that the critical levels set out in Schedule 6 are not exceeded.
OJ No L 24, 29.1.2008, p4, amended by Directive 2009/31/EC (OJ No L 140, 5.6.2009, p114)