Smoke: keep one room clean
Shut the windows and run an air purifier sized for the room.
Wildfire smoke guide →Air quality in Wyoming, county by county
18 Wyoming counties have enough EPA monitor data to count bad-air days. Weighted by population, they averaged about 4 days a year from 2021 to 2025 when the air was unhealthy for sensitive groups or worse.
CDC's model, which estimates every county from monitors and satellites, gives the average Wyoming county, weighted by population, about 2 smoky days (fine particles over 35.4 µg/m³, mostly wildfire smoke) and about 1 high-ozone day a year at its worst spot (2018 to 2022). See every county on the map.
Every Wyoming county with monitors
Most bad-air days first. 11 have a full report. Compare with the worst and the cleanest counties in the US.
| County | Bad-air days a year | |
|---|---|---|
| Platte CountyDust | 10.2 | |
| Albany CountyOzone and particles | 9.4 | |
| Campbell CountyGilletteOzone and particles | 7.8 | |
| Sweetwater CountyRock SpringsOzone and particles | 7.8 | |
| Sheridan CountySheridanOzone and particles | 5.2 | |
| Sublette CountyOzone | 5.2 | |
| Laramie CountyCheyenneOzone and particles | 4.2 | |
| Fremont CountyRivertonOzone and particles | 3.2 | |
| Natrona CountyCasperOzone and particles | 2.6 | |
| Teton CountyJacksonSummer smoke | 2.4 | |
| Johnson CountyOzoneparticles not measured | 1.8 | |
| Converse CountyOzoneparticles not measured | 1.6 | |
| Lincoln CountyOzone and particles | 1.4 | |
| Weston CountyOzoneparticles not measured | 1.2 | |
| Big Horn CountyOzoneparticles not measured | 0.8 | |
| Park CountyCodyRarely badozone not measured | 0.2 | |
| Carbon CountyRarely bad | 0.0 | |
| Uinta CountyEvanstonRarely bad | 0.0 | |
| No Wyoming county with a monitor matches “”. Counties without a monitor aren't listed; a neighbor's numbers are a fair guide, or find it on the map. | ||
Counties without a monitor aren't listed. Air doesn't stop at the county line, so a neighbor's numbers are a fair guide.
What helps on a bad-air day
Check AirNow for today's reading and tomorrow's forecast, then match the step to the pollutant.
Upgrade the furnace filter
MERV 13 catches far more smoke than thin fiberglass filters.
Furnace filters →Questions people ask about air quality in Wyoming
Which county in Wyoming has the worst air?
Among Wyoming counties with EPA monitors, Platte County had the most bad-air days from 2021 to 2025: about 10 bad-air days a year with an AQI over 100. That's about 1 day in 36.
How often is the air bad in Wyoming?
Weighted by population, Wyoming counties with monitors averaged about 4 bad-air days a year from 2021 to 2025 with an AQI over 100, when children, older adults and people with asthma should cut back outdoors. That's about 1 day in 88.
Which county in Wyoming has the cleanest air?
2 of the 18 counties with enough monitor data had no bad-air days at all from 2021 to 2025, including Uinta County and Carbon County. Counties without monitors aren't ranked.
Where can I check today's air quality in Wyoming?
AirNow, run by the EPA and its partners, shows current readings and forecasts by ZIP code, and its fire and smoke map adds smoke plumes and low-cost sensors.
Sources: EPA AirData county AQI summaries, 2021 to 2025; CDC Environmental Public Health Tracking Network modeled PM2.5 and ozone, 2018 to 2022. Updated November 8, 2026.