Regulation 20 Duty in relation to long-term objectives for ozone
(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.