SmogRank / World / United States / Montana / April 2024

Most unhealthy days in Montana, United States, April 2024

11 cities in Montana, United States ranked by their share of unhealthy days over the 30 days. The most unhealthy days: Great Falls, United States, 0 of 30 measured days. A city needs measurements on 70% of the days to be ranked.

Ranked by unhealthy days: the share of each city's measured days with a daily mean over 35.4 µg/m³ (US AQI 101+), Unhealthy for Sensitive Groups or worse on the US EPA's scale. Ties go to the higher average.

← Great Falls 0% 0.75%0
Every city in Montana, United States ranked for April 2024, one column each, ranked by unhealthy days: height is the share of its measured days that were unhealthy, colour its average. Point at it to read a city; tap to open it.
  1. 1Great Falls
    0 of 30
  2. 1Helena Valley West Central
    0 of 30
  3. 3Columbia Falls
    0 of 30
  4. 4Butte
    0 of 30
  5. 5Miles City
    0 of 30
  6. 6Lockwood
    0 of 30
  7. 7Bozeman
    0 of 30
  8. 8Glendive
    0 of 30
  9. 9Lewistown
    0 of 30
  10. 10Havre
    0 of 29
  11. 11Missoula
    0 of 30
Good0–50
Moderate51–100
Sensitive groups101–150
Unhealthy151–200
Very unhealthy201–300
Hazardous301+

The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales

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SmogRank, most polluted cities in Montana, United States, by unhealthy days, PM2.5, April 2024, smogrank.com/us/region/montana/history/2024-04?by=days (accessed 8 Oct 2026).

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