The Air Quality Limit Values (Wales) Regulations 2002

Method of assessment of ambient air quality

8.—(1) The National Assembly must ensure that ambient air quality is assessed in each zone by following the specified method for each relevant pollutant in accordance with its current classification.

(2) Where a zone is classified under regulation 6(1)(a) or (b) in relation to a relevant pollutant—

(a) measurements of that pollutant must be taken at fixed sites either continuously or by random sampling; and

(b) the number of measurements must be sufficiently large to enable the levels of that pollutant to be properly determined.

(3) Schedule 3 has effect for the purpose of determining the location of sampling points for the relevant pollutants.

(4) For each zone classified under regulation 6(1)(a) the National Assembly must ensure that, in respect of a relevant pollutant, the minimum number of fixed sampling points determined in accordance with Schedule 4 is used for sampling the concentrations of that pollutant in that zone.

(5) For each zone classified under regulation 6(1)(b) the National Assembly must ensure that, in respect of a relevant pollutant, the number of fixed sampling points used for sampling of that pollutant in that zone, and the spatial resolution of other techniques, shall be sufficient for the concentrations of that pollutant to be established in accordance with Part I of Schedule 3 and Part I of Schedule 5.

(6) Reference methods for—

(a) the analysis of sulphur dioxide, nitrogen dioxide and oxides of nitrogen;

(b) the sampling and analysis of lead;

(c) the sampling and measurement of PM₁₀;

(d) the sampling and analysis of benzene; and

(e) the analysis of carbon monoxide

are set out in Schedule 6, and these methods must be used unless other methods are used which the National Assembly considers can be demonstrated to give equivalent results.

(7) The National Assembly must ensure that measuring stations to supply representative data on concentrations of PM_2.5 are installed and operated, using any method for the sampling and measurement of PM_2.5 that it considers suitable, and that where possible sampling points for PM_2.5 are co-located with sampling points for PM₁₀.

(8) For zones which are classified under regulation 6(1)(b) or (c), the National Assembly must ensure that the information set out in Part II of Schedule 5 is compiled.

(9) For sulphur dioxide, nitrogen dioxide, oxides of nitrogen, benzene and carbon monoxide measurements of volume must be standardised at a temperature of 293°K and a pressure of 101.3 kPa.