Bad Air Days in Carbon County, Wyoming: under 1 a Year

under 1 bad air days a year

Rare: among the cleanest-air counties EPA monitors. Ranked 942 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly ozone: summer smog (0% particle days).

Which months to watch

Most bad days here fall in March. Averaged over 2016 to 2025.

What actually helps here

Bad air days are rare here. A standard furnace filter is enough; no purifier needed for outdoor air.
On the odd bad day, check AirNow and keep windows shut.

Better or worse than it was

The worst recent year was 2019, with 1 bad day on 364 monitored days.

Date	AQI	Main pollutant
2019-03-21	112	Ozone
2019-03-19	100	Ozone
2018-08-02	90	Ozone
2018-06-11	87	Ozone
2018-07-13	87	Ozone

Most days, not the worst ones

Across 3,553 monitored days from 2016 to 2025, the air in Carbon County rated Good on 94% of them, more often than the 72% typical of monitored counties, and Moderate on 6%. The median day sat at AQI 22; one day in ten went above 35.

The pollutant setting the AQI on an ordinary day here:

nitrogen dioxide60%2,118 days
ozone40%1,430 days

Carbon County by year

Year	Days monitored	Good	Moderate	Over 100	Median AQI	Highest AQI
2025*	362	362	0	0	8	43
2024	356	356	0	0	8	35
2023	362	362	0	0	8	33
2022	361	361	0	0	9	27
2021	348	348	0	0	10	37
2020	304	304	0	0	8	31
2019	364	325	38	1	43	112
2018	365	292	73	0	42	90
2017	365	311	54	0	43	80
2016	366	335	31	0	42	84
2015	365	326	38	1	42	105
2014	365	327	38	0	42	80
2013	360	347	13	0	38	71
2012	354	270	84	0	43	97
2011	358	279	79	0	44	80
2010	349	264	84	1	45	112

*2025 may be a partial year in EPA's file.

Wyoming compared

How this is counted

A bad air day is a day the county's daily AQI from EPA AirData went above 100, the level where EPA tells children, older adults and people with asthma or heart disease to cut back outdoors. Monitors do not run every day, so yearly counts are scaled to 365 days. This is the record, not today's air: for that, check AirNow. More on the method in how the county numbers are made, on the AQI 100 line in what counts as a bad air day, and on why a purifier does not touch ozone in smoke vs ozone.