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

under 1 bad air day a year

Fewer bad air days than most monitored US counties. Ranked 739 of 996 monitored counties, where 1 is worst.

What makes them bad: mostly particles: smoke and dust (100% particle days).

When the bad days come in Park

Most bad days here fall in August and September. Averaged over 2016 to 2025.

Is a purifier worth it 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 2020, with 2 bad days on 122 monitored days.

Date	AQI	Main pollutant
2018-08-19	136	PM2.5
2023-09-05	122	PM2.5
2020-09-18	113	PM2.5
2020-08-22	111	PM2.5
2018-08-20	101	PM2.5

Most days, not the worst ones

Across 2,449 monitored days from 2016 to 2025, the air in Park County rated Good on 93% of them, more often than the 72% typical of monitored counties, and Moderate on 7%. The median day sat at AQI 19; one day in ten went above 42.

The pollutant setting the AQI on an ordinary day here:

fine particles (PM2.5)82%2,017 days
ozone15%374 days
coarse dust (PM10)2%55 days

Every recent year on file

Year	Days monitored	Good	Moderate	Over 100	Median AQI	Highest AQI
2025*	355	348	7	0	13	73
2024	355	322	33	0	13	88
2023	360	343	16	1	14	122
2022	344	314	30	0	20	83
2021	152	129	23	0	14	98
2020	122	112	8	2	15	113
2019	307	292	15	0	38	80
2018	212	194	16	2	31	136
2017	121	106	15	0	18	87
2016	121	115	6	0	16	87
2015	126	118	8	0	18	84
2014	122	113	9	0	16	59
2013	124	118	6	0	20	63
2012	123	106	17	0	21	93
2011	122	113	9	0	21	79
2010	121	113	8	0	21	58

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

Elsewhere in Wyoming

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.