17.8.1001    DEFINITIONS

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.

History: 75-2-111, 75-2-203, MCA; IMP, 75-2-202, 75-2-203, 75-2-204, MCA; NEW, 1993 MAR p. 2919, Eff. 12/10/93; TRANS, from DHES, 1996 MAR p. 2285.