This collection is a sub-subgroup (Bureau) of the Montana Department of Environmental Quality records, RS 494. The Air Quality Bureau currently (as of 2024) operates within the Air, Energy, and Mining Division of DEQ. Please see the primary finding aid for more Montana Department of Environmental Quality records. These records (1973-1989) of the Air Quality Bureau consist of hearing files, subject files, and miscellany.

Records include hearing files (1980-1981) of public testimony concerning proposed air quality standards. There are also subject files (1974-1978) on Air Quality Maintenance Areas in for the Berkeley Pit, Billings, Butte and Anaconda, Great Falls, Helena, Kalispell, Missoula, and other towns statewide; and files concerning the Cabin Creek Coal Mine (Sage Creek Coal Project) (1975-1984), Colstrip (1973-1981), a Flathead River Basin study (1976-1989), Fort Union Coal (1976-1982), air pollution caused by the eruption of Mount Saint Helens (1980), the Poplar River Thermal Generating Project (1974-1988), and tribal assistance to the Flathead and Northern Cheyenne Indian Reservations. (1976-1982). Files are arranged alphabetically and then chronologically within each subject area. (These records have not been completely processed.)