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3 active NWS alerts in MontanaWinter Weather Advisory · Special Weather Statement · Dense Fog Advisory
Read the alert →

Weather tools · Air quality

Air quality in Montana today

AQI, fine particulate and pollutant gas levels, with advice for going outdoors.

overcast clouds 35° overcast cloudsNow

Good

PM2.5 in Montana is currently 1.4 µg/m³, within the WHO guideline.

What should you do at this air quality level?

  • The air is clean. Enjoy exercise and outdoor activities.
  • A good time to open the windows and air out your home.

Pollutants compared with WHO guidelines

PM2.5Fine particles that reach deep into the lungs and blood
1.4µg/m³ · WHO 15
PM10Coarse dust from roads and construction
1.9µg/m³ · WHO 45
NO2Vehicle exhaust and fuel burning
4.4µg/m³ · WHO 25
O3Ground-level ozone, higher in strong sunshine
46.5µg/m³ · WHO 100
SO2Coal and oil burning in industry
0µg/m³ · WHO 40
COIncomplete combustion, vehicle smoke
147µg/m³ · WHO 4000

The vertical line marks the World Health Organization guideline (WHO, 2021). Figures are instantaneous concentrations from the OpenWeather model and are for reference only; for official monitoring and wildfire smoke forecasts, see AirNow.gov (US EPA) and your state air agency.

Air quality ranking by state

Most polluted first
  1. 1 Michigan 70 Moderate
  2. 2 Georgia 69 Moderate
  3. 3 West Virginia 69 Moderate
  4. 4 Vermont 65 Moderate
  5. 5 Indiana 62 Moderate
  6. 6 Alabama 60 Moderate
  7. 7 Arizona 60 Moderate
  8. 8 Tennessee 60 Moderate
  9. 9 Ohio 58 Moderate
  10. 10 Kentucky 57 Moderate
  11. 11 Florida 56 Moderate
  12. 12 Illinois 54 Moderate

See temperatures nationwide →

What is the AQI?

The AQI (Air Quality Index) turns pollutant concentrations into an easy-to-read 0–500 scale: the higher the number, the more polluted the air. This page calculates the AQI on the US Environmental Protection Agency scale (US EPA, 2024 update) from PM2.5, the pollutant with the greatest health impact, the same scale used by AirNow.gov.

Fine particles tend to build up on calm mornings and evenings, during temperature inversions in winter valleys and during heavy traffic. In summer and fall, smoke from wildfires — sometimes hundreds of miles away — can push the AQI into unhealthy levels. Ground-level ozone peaks on hot, sunny afternoons. After rain or a cold front, the air is usually noticeably cleaner.

More forecasts for Montana

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