The Air Quality Limit Values Regulations 2001

Method of assessment of ambient air quality

7.—(1) The Secretary of State shall ensure that ambient air quality is assessed in each zone by following the appropriate method for each relevant pollutant in accordance with its current classification.

(2) Where a zone is classified under regulation 5(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 shall have effect for the purposes of determining the location of sampling points for the relevant pollutants.

(4) For each zone classified under regulation 5(1)(a) in relation to a relevant pollutant, the Secretary of State shall ensure that 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 5(1)(b) in relation to a relevant pollutant, the Secretary of State shall ensure that the number of fixed sampling points used for sampling 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; and

(c) the sampling and measurement of PM₁₀,

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

(7) The Secretary of State shall ensure that—

(a) measuring stations to supply representative data on concentrations of PM_2.5 are installed and operated using methods for the sampling and measurement of PM_2.5 that she considers suitable; and

(b) sampling points for PM_2.5 are, where possible, co-located with sampling points for PM₁₀.

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

(9) For sulphur dioxide, nitrogen dioxide and oxides of nitrogen measurements of volume must be standardised at a temperature of 293°K and a pressure of 101,3 kPa.