Fixed measurement
14.—(1) This regulation applies in cases where, in relation to one or more pollutants, a zone is assessed in accordance with the methods referred to in regulation 13(2), (3)(a) or (7).
(2) Where a zone is assessed in accordance with regulation 13(2) or (3)(a), measurements of the relevant pollutant must, subject in the case of nitrogen dioxide to the requirements imposed by regulation 15(7) in respect of the assessments required by that regulation, be taken at fixed sites either continuously or by random sampling and the number of measurements must be sufficiently large to enable concentrations of the pollutant to be properly determined.
(3) Where a zone is assessed in accordance with regulation 13(2), the National Assembly may supplement information from sampling points for fixed measurement with information from modelling techniques where it considers this will provide an adequate level of information on ambient air quality.
(4) Where a zone is assessed in accordance with regulation 13(7), the National Assembly may supplement information from sampling points with information from modelling or indicative measurements provided that the conditions set out in regulation 15(6) are complied with.