ARM 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/m 3 ) ; (ii) a 24-hour average of 5.0 µg/m 3 ; or (iii) a three-hour average of 25.0 µg/m 3 . (b) for PM-10: (i) an annual average of 1.0 µg/m 3 ; or (ii) a 24-hour average of 5.0 µg/m 3 . (c) for nitrogen dioxide, an annual average of 1.0 µg/m 3 . (d) for carbon monoxide: (i) an eight-hour average of 0.5 milligrams per cubic meter (mg/m 3 ) ; or (ii) a one-hour average of 2.0 mg/m 3 .