Daily Air Quality Index summaries from EPA monitors in Fremont, Wyoming, 1985–2025.
70%
Good days in 2025
47
Median daily AQI, 2025
0
Days above 100 in 2025
365
Days with an AQI in 2025 (of 365)
In 2025, EPA reported a daily Air Quality Index (AQI) for Fremont, Wyoming on 365 days. 254 of those days (70%) were in the Good range, and the median daily AQI was 47. That median is higher than the typical monitored county in Wyoming (median 41 across 17 counties), and higher than the typical monitored U.S. county (40). The main pollutant was ozone on 309 days. Across the years with fuller monitoring, the share of Good days fell: an average of 86% in 1988–1990 versus 62% in 2023–2025.
Years with fewer than 120 monitored days (1985, 1986, 1987) are shown in the table but left out of comparisons and trend statements.
How the days broke down each year
Each bar is one year. The colored segments show the share of monitored days that fell in each AQI category.
Good
Moderate
Unhealthy for Sensitive Groups
Unhealthy
Very Unhealthy
Hazardous
Typical and high-end AQI over time
The median is the middle day of the year. The 90th percentile is the level that only the highest 10% of days exceeded.
Median daily AQI
90th-percentile daily AQI
Main pollutant by day, 2025
On each monitored day, the AQI reflects whichever measured pollutant had the highest index. This counts how many days each pollutant set the AQI. A pollutant that was not measured here cannot appear.
Pollutant
Days as main pollutant
Share of monitored days
Ozone
309
85%
Fine particles (PM2.5)
56
15%
Year-by-year data
Annual AQI summary by year
Year
Days with AQI
Good
Moderate
Unhealthy for Sensitive Groups
Unhealthy
Very Unhealthy
Hazardous
Median AQI
90th pct.
Max AQI
Main pollutant
2025
365
254
111
0
0
0
0
47
64
100
Ozone
2024
366
210
151
5
0
0
0
49
74
139
Ozone
2023
365
215
147
3
0
0
0
49
65
110
Ozone
2022
365
254
111
0
0
0
0
46
61
100
Ozone
2021
365
240
117
8
0
0
0
46
77
141
Ozone
2020
366
282
78
5
1
0
0
45
60
161
Ozone
2019
365
291
73
1
0
0
0
45
60
122
Ozone
2018
365
250
115
0
0
0
0
46
67
97
Ozone
2017
365
249
114
2
0
0
0
47
66
118
Ozone
2016
366
298
68
0
0
0
0
44
61
84
Ozone
2015
365
276
89
0
0
0
0
45
60
97
Ozone
2014
365
294
70
1
0
0
0
45
57
105
Ozone
2013
365
259
106
0
0
0
0
46
61
100
Ozone
2012
366
214
147
5
0
0
0
47
75
117
Ozone
2011
365
201
162
2
0
0
0
49
77
136
Ozone
2010
365
228
136
1
0
0
0
48
71
112
Ozone
2009
364
250
104
8
2
0
0
46
72
169
Ozone
2008
365
240
124
1
0
0
0
44
71
101
Ozone
2007
316
217
93
6
0
0
0
45
74
140
Ozone
2006
122
85
37
0
0
0
0
32
61
80
PM2.5
2005
123
94
28
1
0
0
0
26
69
105
PM2.5
2004
121
87
30
4
0
0
0
27
83
126
PM2.5
2003
122
89
32
1
0
0
0
28
69
102
PM2.5
2002
122
79
43
0
0
0
0
31
74
100
PM2.5
2001
122
80
35
6
1
0
0
38
84
151
PM2.5
2000
125
88
35
2
0
0
0
33
77
109
PM2.5
1999
178
175
3
0
0
0
0
18
33
80
PM10
1998
230
214
16
0
0
0
0
21
48
69
PM10
1997
233
219
14
0
0
0
0
20
43
74
PM10
1996
251
242
9
0
0
0
0
20
40
63
PM10
1995
262
224
38
0
0
0
0
20
54
70
PM10
1994
219
179
40
0
0
0
0
23
62
88
PM10
1993
177
135
42
0
0
0
0
21
63
91
PM10
1992
180
140
40
0
0
0
0
22
65
85
PM10
1991
173
134
39
0
0
0
0
24
63
89
PM10
1990
142
127
15
0
0
0
0
18
54
88
PM10
1989
165
141
24
0
0
0
0
21
57
81
PM10
1988
170
139
31
0
0
0
0
31
64
83
PM10
1987
91
68
23
0
0
0
0
37
67
97
PM10
1986
54
42
9
3
0
0
0
23
77
108
PM10
1985
53
41
12
0
0
0
0
31
78
90
PM10
What this data can and can’t tell you
It is a county-level summary. EPA reports one AQI per day for the county, based on the monitors operating there. Air at a particular street, school or home can differ, especially near roads, industry or wildfire smoke.
It is not a health assessment. The AQI is EPA’s scale for communicating daily air quality. A county’s history can’t tell you what the health risk is for any particular person. For daily conditions and health guidance, see AirNow.
Rules change over time. EPA has revised AQI breakpoints, most recently for fine particles in 2024, so some year-to-year change can reflect the scale rather than the air.
Counties in Wyoming with a similar median AQI in 2025
