Air quality in United States

Air quality in Montana today

Updated Sun, 25 Oct 2026 17:13:57 GMT

Good: average US AQI 41 across 6 cities in Montana Worst now: Butte (53); cleanest: Billings (26).

Live US AQI, PM2.5 and ozone for cities across Montana, compared with the United States average.

Right now the modelled air quality in Montana averages a US AQI of 41 (Good) across the 6 cities we track. By category: 4 Good, 2 Moderate (of 6).

That is 7 points cleaner than the United States average of 48, ranking 27 of 51 states from cleanest to most polluted.

Butte has the worst air at 53 (PM2.5 9.2 µg/m³), and Billings the cleanest at 26. No tracked city is above 100, so no group needs to change plans.

Montana cities by AQI (most polluted first)

City	US AQI	Category	PM2.5 µg/m³	PM10 µg/m³	Ozone µg/m³
Butte	53	Moderate	9.2	11	92
Helena	51	Moderate	6.2	8	83
Bozeman	44	Good	7.5	9	70
Kalispell	39	Good	1.8	2	66
Great Falls	31	Good	3.6	5	53
Billings	26	Good	3.4	5	60

US AQI	Category	What it means
0-50	Good	Air quality is satisfactory and poses little or no risk; a good time for outdoor activity.
51-100	Moderate	Acceptable for most people. Unusually sensitive people should consider shortening long or heavy exertion outdoors.
101-150	Unhealthy for Sensitive Groups	People with heart or lung disease, older adults, children and teens should cut back on prolonged or heavy exertion outdoors.
151-200	Unhealthy	Everyone should reduce prolonged or heavy exertion outdoors; sensitive groups should avoid it and keep windows closed.
201-300	Very Unhealthy	Health alert: everyone should avoid prolonged or heavy exertion outdoors, and sensitive groups should stay indoors.
301-500	Hazardous	Emergency conditions: everyone should avoid all outdoor physical activity and stay indoors with filtered air if possible. The scale tops out at 500; heavier dust or smoke is shown as 500.

Modelled by CAMS (Copernicus) via Open-Meteo, refreshed twice a day; read hour by hour from the forecast.