Assessment criteria
12.—(1) The Department shall assess concentrations of arsenic, cadmium, nickel and benzo(a)pyrene in ambient air in all zones.
(2) In zones where the levels of arsenic, cadmium, nickel and benzo(a)pyrene are above the upper assessment threshold referred to in regulation 11, measurement is mandatory but may be supplemented by modelling techniques to provide an adequate level of information on ambient air quality.
(3) In zones where the levels of those pollutants are between the upper and lower assessment thresholds referred to in regulation 11, measurement is mandatory but may be supplemented by indicative measurements as referred to in Section I of Annex IV to Council Directive 2004/107/EC or modelling, or both.
(4) In zones where the levels of those pollutants are below the lower assessment thresholds, modelling or objective estimation techniques may be used instead of measurement.