Sampling points
15.—(1) Where the National Assembly assesses concentrations of a pollutant within a zone in accordance with the methods referred to at regulation 13(2), (3)(a) or (7) it must, in respect of each pollutant, ensure that—
(a)a minimum number of sampling points are established within each zone, in accordance with paragraphs (2) to (6); and
(b)each sampling point is located in accordance with the relevant Parts of Schedule 5.
(2) In cases where a zone is assessed in accordance with—
(a)regulation 13(2), and paragraph (3)(a) of this regulation does not apply; or
(b)regulation 13(7), and paragraph (4) of this regulation does not apply,
the minimum number of sampling points is specified in the relevant Parts of Schedule 6.
(3) Where a zone is assessed in accordance with—
(a)regulation 13(2) and, within that zone, the National Assembly supplements fixed measurements with modelling techniques in accordance with regulation 14(3); or
(b)regulation 13(3)(a),
the minimum number of sampling points required for each pollutant must be a number that the National Assembly determines is sufficient, taken together with the spatial resolution of the other techniques employed, for concentrations of the relevant pollutant to be established.
(4) Where a zone is assessed in accordance with regulation 13(7), the National Assembly may reduce the number of sampling points required under paragraph (2)(b) provided that the conditions set out in paragraphs (5) or (6) are met.
(5) In the case of zones where—
(a)five years of measurement have been carried out; and
(b)during each of those years, concentrations of ozone have been below the long-term objectives,
the National Assembly may determine the number of sampling points in accordance with Part 5 of Schedule 6.
(6) In the case of zones in which the National Assembly supplements the information obtained from sampling points for fixed measurement with information from modelling or indicative measurement in accordance with regulation 14(4), it may reduce the number of sampling points provided that—
(a)the modelling techniques adopted provide an adequate level of information for the assessment of air quality with regard to the—
(i)target values,
(ii)information threshold, and
(iii)alert threshold;
(b)the number of sampling points to be installed and the spatial resolution of other techniques are sufficient for the concentration of ozone to be established and to enable the compilation of assessment results as specified in Part 3 of Schedule 7;
(c)the number of sampling points in each zone amounts to—
(i)at least one sampling point per two million inhabitants, or
(ii)one sampling point per 50,000 km2,
whichever produces the greater number of sampling points;
(d)each zone contains at least one sampling point; and
(e)concentrations of nitrogen dioxide are assessed at all remaining sampling points except rural background stations, in accordance with paragraph (7).
(7) The National Assembly must ensure that—
(a)concentrations of nitrogen dioxide are assessed—
(i)at least at 50 per cent of the sampling points established for ozone in accordance with Part 4 of Schedule 6, or
(ii)where paragraph (6) applies, in accordance with sub-paragraph (e) of that paragraph;
and
(b)the measurement of nitrogen dioxide taken at these sampling points is continuous, except at rural background stations where other measurement methods may be used.