13.—(1) Subject to paragraph (2), the Scottish Ministers shall assess concentrations of a Group A pollutant by fixed measurement where–
(a)the assessment takes place within an agglomeration; or
(b)in any other zone, representative concentrations of that pollutant exceed the relevant upper assessment threshold.
(2) Where the zone concerned is the same as that established under the Air Quality Limit Values (Scotland) Regulations 2003(1) (“the 2003 Regulations”), the Scottish Ministers may continue to use the method by which concentrations of a Group A pollutant were assessed within that zone under the 2003 Regulations (“the 2003 method”).
(3) Except where fixed measurement is required by paragraph (1) or they continue to use the 2003 method in accordance with paragraph (2), and, in the case of nitrogen dioxide, subject to the requirements imposed by regulation 15(7), the Scottish Ministers may assess concentrations of a Group A pollutant by any one of the following methods–
(a)fixed measurement;
(b)combined measurement; or
(c)the sole use of modelling or objective estimation techniques, provided that representative concentrations of the pollutant in the zone concerned are below the relevant lower assessment threshold.
(4) The Scottish Ministers shall assess concentrations of a Group B pollutant by fixed measurement in any zone in which representative concentrations of that pollutant exceed the relevant upper assessment threshold.
(5) Except where fixed measurement is required by paragraph (4), the Scottish Ministers may assess concentrations of a Group B pollutant by one of the following methods:–
(a)fixed measurement;
(b)combined measurement; or
(c)the sole use of modelling or objective estimation techniques, provided that representative concentrations of the pollutant in the zone concerned are below the relevant lower assessment threshold.
(6) For the purposes of paragraphs (1) and (3) to (5), the Scottish Ministers shall determine the representative concentrations in accordance with Part 3 of Schedule 4.
(7) The Scottish Ministers shall review the method by which concentrations of a Group A or Group B pollutant are assessed at least once every five years or earlier if there are significant changes in activities affecting concentrations of the relevant pollutant within the zone concerned.
(8) Where the Scottish Ministers continue to use the 2003 method, the date from which the period of review commences is the later of–
(a)the date the zone was classified under regulation 7(1) of the 2003 Regulations; or
(b)the date on which that classification was last reviewed under regulation 8 of those Regulations.
(9) The Scottish Ministers shall assess concentrations of ozone by fixed measurement if, within the zone concerned, concentrations have exceeded a long-term objective during any of the previous five years of measurement.
(10) In cases where fewer than five years' information on concentrations is available, the Scottish Ministers may assess concentrations of ozone by combining the following:–
(a)measurement campaigns of short duration at times and locations which they consider are likely to be typical of the highest pollution levels; and
(b)results from emission inventories and modelling.
S.S.I. 2003/428 amended by S.S.I. 2003/547 and S.S.I. 2005/300.