For the purpose of this subchapter:
(1) The definitions contained in ARM 17.8.901 shall be applicable.
(2) "Cause or contribute" means, in regard to an ambient air quality impact caused by emissions from a major source or modification, an ambient air quality impact that exceeds the significance level as defined in (3) , for any pollutant at any location.
(3) "Significance level" means, for any of the following pollutants, an ambient air quality impact greater than any of the averages cited below:
(a) for sulfur dioxide:
(i) an annual average of 1.0 micrograms per cubic meter (µg/m3) ;
(ii) a 24-hour average of 5.0 µg/m3; or
(iii) a three-hour average of 25.0 µg/m3.
(b) for PM-10:
(i) an annual average of 1.0 µg/m3; or
(ii) a 24-hour average of 5.0 µg/m3.
(c) for nitrogen dioxide, an annual average of 1.0 µg/m3.
(d) for carbon monoxide:
(i) an eight-hour average of 0.5 milligrams per cubic meter (mg/m3) ; or
(ii) a one-hour average of 2.0 mg/m3.