9.—(1) The Department shall assess the levels of ozone in ambient air in all zones.
(2) The Department shall ensure that fixed measurements are taken in any zone where the concentrations of ozone have exceeded the long-term objectives specified in Schedule 4 during any of the previous five years of measurement.
(3) Save as provided for in paragraph (4) for the purposes of paragraph (2), measurements shall be taken in accordance with the reference measurement methods specified in point 8 of Section A of Annex VI to the Directive.
(4) Alternative methods to those referred to in paragraph (3) may be used provided the conditions set out in Section B of that Annex are complied with.