84Duties of local authorities in relation to designated areas
(1)Where an order under section 83 above comes into operation, the local authority which made the order shall, for the purpose of supplementing such information as it has in relation to the designated area in question, cause an assessment to be made of—
(a)the quality for the time being, and the likely future quality within the relevant period, of air within the designated area to which the order relates; and
(b)the respects (if any) in which it appears that air quality standards or objectives are not being achieved, or are not likely within the relevant period to be achieved, within that designated area.
(2)A local authority which is required by subsection (1) above to cause an assessment to be made shall also be under a duty—
(a)to prepare, before the expiration of the period of twelve months beginning with the coming into operation of the order mentioned in that subsection, a report of the results of that assessment; and
(b)to prepare, in accordance with the following provisions of this Part, a written plan (in this Part referred to as an “action plan”) for the exercise by the authority, in pursuit of the achievement of air quality standards and objectives in the designated area, of any powers exercisable by the authority.
(3)An action plan shall include a statement of the time or times by or within which the local authority in question proposes to implement each of the proposed measures comprised in the plan.
(4)A local authority may from time to time revise an action plan.
(5)This subsection applies in any case where the local authority preparing an action plan or a revision of an action plan is the council of a district in England which is comprised in an area for which there is a county council; and if, in a case where this subsection applies, the county council disagrees with the authority about the contents of the proposed action plan or revision of the action plan—
(a)either of them may refer the matter to the Secretary of State;
(b)on any such reference the Secretary of State may confirm the authority’s proposed action plan or revision of the action plan, with or without modifications (whether or not proposed by the county council) or reject it and, if he rejects it, he may also exercise any powers of his under section 85 below; and
(c)the authority shall not finally determine the content of the action plan, or the revision of the action plan, except in accordance with his decision on the reference or in pursuance of directions under section 85 below.