Method of assessment of ambient air quality
7.—(1) The Department shall ensure that ambient air quality is assessed in each zone by following the appropriate method for ozone in accordance with its current classification.
(2) For each zone classified under Regulation 6(2) in relation to ozone, the Department shall ensure that the minimum number of fixed sampling points determined in accordance with Part I of Schedule 3 is used for sampling the concentrations of ozone in that zone.
(3) For zones to which Regulation 7(2) applies, the Department shall ensure that measurements of nitrogen dioxide are made at a minimum of 50 per cent of the ozone sampling points required by Part I of Schedule 3.
(4) The measurements of nitrogen dioxide required by paragraph (3) shall be continuous, except at rural background stations, where other measurement methods may be used.
(5) For zones to which Regulation 7(3) applies, the number of fixed sampling points required by Part I of Schedule 3 may be reduced provided that –
(a)the supplementary methods prescribed by Regulation 6(3) provide an adequate level of information for the assessment of air quality with regard to target values, information and alert thresholds;
(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 in accordance with the data quality objectives specified in Part I of Schedule 5 and lead to assessment results as specified in Part II of Schedule 5;
(c)the number of sampling points in each zone amounts to at least one sampling point per two million inhabitants, or 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)nitrogen dioxide is measured at all remaining sampling points except rural background stations.
(6) The results of modelling and/or indicative measurements carried out in zones to which paragraph (5) applies shall be taken into account for the assessment of air quality with respect to target values.
(7) For zones where five years of measurement have been carried out, and during each of the previous five years of measurement concentrations are below the long-term objectives, the number of continuous measurement stations shall be determined in accordance with Part II of Schedule 3.
(8) Schedule 2 shall have effect for determining the location of sampling points for the fixed measurement of ozone.
(9) For ozone precursor substances, the Department shall ensure that –
(a)at least one measuring station to supply data on concentrations of the ozone precursor substances listed in Schedule 4 is installed and operated within Northern Ireland; and
(b)in choosing the number and siting of measuring stations for ozone precursor substances, account shall be taken of the objectives, methods and recommendations set out in Schedule 4.
(10) Reference methods for analysis of ozone are set out in Schedule 6, and these methods must be used unless other methods are used which the Department considers can be demonstrated to give equivalent results.
(11) For ozone, measurements of volume must be standardised at a temperature of 293K and a pressure of 101.3kPa.