U.S. Code of Federal Regulations
Regulations most recently checked for updates: Aug 27, 2025
The Montana Emergency Episode Avoidance Plan was revised with an August 2, 2004 submittal by the Governor. The August 2, 2004 Emergency Episode Avoidance Plan classified the Air Quality Control Regions (AQCR) as follows:
| Air quality control regions (AQCR) | Pollutant | ||||
|---|---|---|---|---|---|
| Particulate matter | Sulfur oxide | Nitrogen
dioxide | Carbon
monoxide | Ozone | |
| Billings Intrastate AQCR 140 | III | III | III | III | III |
| Great Falls Intrastate AQCR 141 | III | III | III | III | III |
| Helena Intrastate AQCR 142 | III | III | III | III | III |
| Miles City Intrastate AQCR 143 | III | III | III | III | III |
| Missoula Intrastate AQCR 144 | III | III | III | III | III |
