Air Quality Rankings for Montana 2026

Montana has 19 cities with EPA air quality data. Lake, Montana has the cleanest air with a 5-year average AQI of 10. Missoula, Montana has the highest AQI at 54.

#	City	5yr Avg AQI	Current AQI	Worst Pollutant	Trend	Grade
1	Lake, Montana	10	13	PM2.5	Stable	B
2	Powell, Montana	11	14	PM2.5	Stable	B
3	Roosevelt, Montana	14	13	PM2.5	Stable	B
4	Sheridan, Montana	16	18	PM2.5	Stable	B
5	Ravalli, Montana	22	22	PM2.5	Improving	B
6	Rosebud, Montana	23	3	Ozone	Improving	A
7	Silver Bow, Montana	27	31	PM2.5	Improving	B
8	Cascade, Montana	30	50	PM2.5	Improving	B
9	Gallatin, Montana	32	26	PM2.5	Stable	B
10	Yellowstone, Montana	33	29	PM2.5	Stable	B
11	Sanders, Montana	36	37	PM2.5	Worsening	D
12	Phillips, Montana	36	38	Ozone	Stable	C
13	Richland, Montana	38	39	Ozone	Stable	B
14	Fergus, Montana	40	41	Ozone	Worsening	C
15	Flathead, Montana	40	43	PM2.5	Stable	C
16	Powder River, Montana	41	44	Ozone	Worsening	C
17	Lewis and Clark, Montana	44	45	Ozone	Stable	C
18	Lincoln, Montana	52	53	PM2.5	Worsening	C
19	Missoula, Montana	54	53	PM2.5	Improving	C

Air quality data for Montana is sourced from the EPA Air Quality System (AQS), which monitors outdoor air quality at thousands of stations nationwide.
— EPA Air Quality System

Frequently Asked Questions

Lake, Montana has the best air quality in Montana with a 5-year average AQI of 10 and a grade of B.

Montana has 19 cities with EPA air quality monitoring data in our database, covering multiple years of AQI measurements.

The Air Quality Index (AQI) measures five major pollutants: ground-level ozone, particulate matter (PM2.5 and PM10), carbon monoxide, sulfur dioxide, and nitrogen dioxide. Lower AQI values indicate cleaner air — 0-50 is "Good," while 150+ is "Unhealthy."

Sources: EPA Air Quality System (AQS)

Cities ranked by 5-year average AQI (lower is better). Grades factor in average AQI, trend direction, unhealthy days, and dominant pollutant.

Cleanest Cities Nationwide →All Air Quality in Montana →