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Air quality in Wyoming

EPA monitors report from 19 of Wyoming’s 23 counties. That is the honest limit of this page: the other 4 are not measured, not clean. In 2025 the most affected monitored county was Albany County, with 12 days above the moderate category.

19
Counties with monitors
4
Counties without
47
Days above moderate, 2025
Summed across monitored counties
10.2%
Adults with asthma
Population-weighted county estimate

County by county

Monitored Wyoming counties

GoodModerateUnhealthy for sensitive groupsUnhealthyVery unhealthyHazardous
County90th %ile AQIAbove moderateMax AQI2025 days by category
Albany County7712172
Platte County4712723
Sweetwater County648118
Sublette County645164
Weston County585136
Big Horn County512119
Campbell County622156
Laramie County641108
Carbon County33043
Converse County49063
Fremont County640100
Johnson County49084
Lincoln County26077
Natrona County54076
Park County28073
Sheridan County51075
Teton County54090
Uinta County19050
Washakie County26068

EPA Air Quality System annual summaries by county, 2025. The 90th percentile AQI describes a day worse than nine out of ten, which is a steadier measure than the annual maximum a single wildfire can set.

Not measured

4 counties without a monitor

No EPA monitor reported from these counties, so there is no air quality record to publish. Their radon zone is known, and radon is measured in the building rather than the air outside it.

Other states

Air quality elsewhere