Daily Air Quality Index summaries from EPA monitors in Tooele, Utah, 1993–2025.
74%
Good days in 2025
44
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 Tooele, Utah on 365 days. 271 of those days (74%) were in the Good range, and the median daily AQI was 44. That median is about the same as the typical monitored county in Utah (median 45 across 15 counties), and higher than the typical monitored U.S. county (40). The main pollutant was ozone on 301 days. Across the years with fuller monitoring, the share of Good days fell: an average of 89% in 1993–2002 versus 68% in 2023–2025.
Years with fewer than 120 monitored days (1997, 1999, 2000, 2001, 2003, 2005…) 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
301
82%
Fine particles (PM2.5)
64
18%
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
271
93
1
0
0
0
44
64
101
Ozone
2024
366
227
127
12
0
0
0
46
77
143
Ozone
2023
365
248
117
0
0
0
0
45
71
97
Ozone
2022
365
248
111
6
0
0
0
44
72
119
Ozone
2021
365
229
120
14
2
0
0
43
77
157
Ozone
2020
366
253
108
4
1
0
0
43
70
162
Ozone
2019
365
286
77
2
0
0
0
44
61
117
Ozone
2018
365
204
151
10
0
0
0
47
81
138
Ozone
2017
365
209
139
17
0
0
0
48
80
147
Ozone
2016
366
252
107
6
1
0
0
44
67
166
Ozone
2015
365
299
62
4
0
0
0
33
58
143
PM2.5
2014
365
289
75
1
0
0
0
39
61
105
PM2.5
2013
343
210
118
15
0
0
0
47
77
147
PM2.5
2012
366
225
134
6
1
0
0
46
71
169
PM2.5
2011
364
231
126
7
0
0
0
47
74
119
PM2.5
2010
365
174
181
8
2
0
0
51
76
162
PM2.5
2009
365
104
251
9
1
0
0
54
76
163
PM2.5
2008
357
149
203
5
0
0
0
52
71
129
PM2.5
2007
281
143
126
12
0
0
0
50
84
122
PM2.5
2006
213
103
98
12
0
0
0
51
90
143
Ozone
2005
111
61
38
10
2
0
0
49
101
159
Ozone
2003
60
50
9
1
0
0
0
25
62
122
PM2.5
2002
120
91
24
3
2
0
0
34
71
156
PM2.5
2001
114
85
27
2
0
0
0
30
67
142
PM2.5
2000
112
86
26
0
0
0
0
26
63
98
PM2.5
1999
100
88
12
0
0
0
0
28
54
90
PM2.5
1997
58
58
0
0
0
0
0
14
25
42
PM10
1996
48
47
1
0
0
0
0
17
31
59
PM10
1995
61
60
1
0
0
0
0
19
35
51
PM10
1994
311
295
16
0
0
0
0
22
41
90
PM10
1993
225
214
10
1
0
0
0
22
39
116
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 Utah with a similar median AQI in 2025
