11.—(1) The National Assembly must, in accordance with,—
(a)paragraphs (2) to (4), prepare action plans; and
(b)paragraph (5), implement action plans.
(2) The action plans must indicate the measures to be taken within any zone in the short term in order to achieve the objectives set out in paragraph (3) in the event of circumstances in which the National Assembly considers there is a risk that any one of the following will be exceeded—
(a)a limit value;
(b)the alert threshold for nitrogen dioxide or sulphur dioxide; or
(c)subject to paragraph (4), the alert threshold for ozone.
(3) The objectives of each action plan are to—
(a)reduce the risk that the relevant limit value or alert threshold will be exceeded; or
(b)where it is not possible to prevent the occurrence, limit its duration or severity.
(4) In relation to ozone, the obligation imposed by paragraph (1)(a) only applies insofar as, taking into account geographical, meteorological and economic conditions, the National Assembly considers there is significant potential for the objectives set out in paragraph (3) to be achieved.
(5) The National Assembly must, when it considers that the risks referred to in paragraph (2) arise within any zone, implement the measures indicated in the relevant action plans within the zone concerned to the extent it considers necessary in the circumstances of the particular case.
(6) Schedule 3 has effect in prescribing—
(a)alert thresholds for nitrogen dioxide and sulphur dioxide, in Part 1 of that Schedule; and
(b)the alert threshold and information threshold for ozone, in Part 2 of that Schedule.