Daily Air Quality Index summaries from EPA monitors in Laramie, Wyoming, 1984–2025.
75%
Good days in 2025
45
Median daily AQI, 2025
1
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 Laramie, Wyoming on 365 days. 274 of those days (75%) were in the Good range, and the median daily AQI was 45. 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 345 days. Across the years with fuller monitoring, the share of Good days fell: an average of 97% in 2008–2010 versus 75% in 2023–2025.
Years with fewer than 120 monitored days (2002, 2003, 2004, 2005, 2006, 2007…) 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
345
95%
Fine particles (PM2.5)
19
5%
Nitrogen dioxide (NO₂)
1
<1%
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
274
90
1
0
0
0
45
64
108
Ozone
2024
366
271
91
3
1
0
0
45
67
151
Ozone
2023
365
275
85
4
1
0
0
45
61
156
Ozone
2022
363
297
66
0
0
0
0
42
58
90
Ozone
2021
364
261
92
11
0
0
0
44
77
126
Ozone
2020
366
313
48
3
2
0
0
39
58
159
Ozone
2019
365
296
69
0
0
0
0
43
58
74
Ozone
2018
365
288
76
1
0
0
0
43
61
109
Ozone
2017
365
267
95
1
2
0
0
45
64
163
Ozone
2016
366
305
61
0
0
0
0
43
54
87
Ozone
2015
365
302
62
0
1
0
0
43
61
152
Ozone
2014
365
284
81
0
0
0
0
44
61
97
Ozone
2013
365
271
91
3
0
0
0
43
67
115
Ozone
2012
366
225
139
2
0
0
0
47
74
108
Ozone
2011
365
256
108
1
0
0
0
44
67
101
Ozone
2010
121
119
2
0
0
0
0
23
38
54
PM2.5
2009
121
120
1
0
0
0
0
19
35
68
PM2.5
2008
120
113
7
0
0
0
0
22
43
71
PM2.5
2007
118
115
3
0
0
0
0
22
39
60
PM2.5
2006
119
112
7
0
0
0
0
21
38
62
PM2.5
2005
111
108
3
0
0
0
0
21
39
53
PM2.5
2004
118
110
8
0
0
0
0
23
43
84
PM2.5
2003
117
108
9
0
0
0
0
24
44
68
PM2.5
2002
115
103
12
0
0
0
0
22
52
62
PM2.5
2001
113
106
7
0
0
0
0
25
44
59
PM2.5
2000
116
105
11
0
0
0
0
28
49
62
PM2.5
1999
109
100
9
0
0
0
0
29
49
69
PM2.5
1998
62
61
1
0
0
0
0
17
31
52
PM10
1997
51
51
0
0
0
0
0
12
19
25
PM10
1996
57
57
0
0
0
0
0
14
23
31
PM10
1995
45
45
0
0
0
0
0
11
24
37
PM10
1994
49
49
0
0
0
0
0
15
26
46
PM10
1993
57
57
0
0
0
0
0
13
22
33
PM10
1992
58
58
0
0
0
0
0
15
23
32
PM10
1991
77
76
1
0
0
0
0
18
28
52
PM10
1988
54
53
1
0
0
0
0
16
26
52
PM10
1987
50
50
0
0
0
0
0
29
36
45
PM10
1986
61
61
0
0
0
0
0
14
26
35
PM10
1985
57
56
1
0
0
0
0
22
34
56
PM10
1984
5
5
0
0
0
0
0
18
28
28
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
