SmogRank / Countries / United States / Montana
Most polluted cities in Montana, United States
6 measured cities ranked by PM2.5, last 7 days. Worst: Great Falls at 9.9 µg/m³, #538 in the world.
| # | City | µg/m³ | |
|---|---|---|---|
| 1 | Great Falls Montana | 9.9 | |
| 2 | Bozeman Montana | 6.0 | |
| 3 | Billings Montana | 4.9 | |
| 4 | Butte Montana | 3.9 | |
| 5 | Helena Montana | 3.5 | |
| 6 | Missoula Montana | 3.3 |
Good 0–9.0Moderate 9.1+Unhealthy for sensitive groups 35.5+Unhealthy 55.5+Very unhealthy 125.5+Hazardous 225.5+No data
Estimated: cities without a monitor
Montana cities we can't measure, with model estimates for the last 7 days. Listed by population, not ranked: estimates aren't precise enough to rank. Model estimates from the Copernicus Atmosphere Monitoring Service (CAMS), adjusted to measured cities nearby where there are any. Adjusted, a single day lands within ×1.5 of what a monitor would read about two times in three; unadjusted, it can be off by half or double. Treat them as a guide, not a measurement.
| City | 7-day estimate |
|---|---|
| Kalispell estimated | ≈ 5 µg/m³ |
Updated 2026-10-01 14:07 UTC. Values are PM2.5 in µg/m³ (fine particles), the median of each city's monitors.