(1) For the purposes of this subchapter, terms have the meaning as defined in 40 CFR 93.152.

(2) For the purposes of this subchapter and 40 CFR Part 93, subpart B, as adopted by reference in this subchapter, the following additional definitions apply:

(a) "MPO" means Metropolitan Planning Organization and is that organization designated as being responsible, together with the state, for conducting the continuing, cooperative, and comprehensive planning process under 23 USC 134 and 49 USC 1607. This includes the MPOs in Billings, Great Falls, and Missoula, any successors to these MPOs, and any MPO that is subsequently created for any area.

(b) "State air quality agency" means the Montana Department of Environmental Quality ("department" or "DEQ"), or its successor agency.