Daily Air Quality Index summaries from EPA monitors in Salt Lake, Utah, 1980–2025.
33%
Good days in 2025
57
Median daily AQI, 2025
16
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 Salt Lake, Utah on 365 days. 121 of those days (33%) were in the Good range, and the median daily AQI was 57. That median is higher than 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 230 days. Across the years with fuller monitoring, the share of Good days held roughly steady: an average of 36% in 1980–1982 versus 38% in 2023–2025.
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
230
63%
Fine particles (PM2.5)
110
30%
Coarse particles (PM10)
15
4%
Nitrogen dioxide (NO₂)
10
3%
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
121
228
15
1
0
0
57
90
175
Ozone
2024
366
150
173
38
4
1
0
54
101
230
Ozone
2023
365
149
200
15
1
0
0
54
90
154
Ozone
2022
365
101
236
28
0
0
0
60
98
147
Ozone
2021
365
122
195
39
9
0
0
59
108
177
Ozone
2020
366
143
200
21
1
1
0
54
93
214
PM2.5
2019
365
132
216
17
0
0
0
58
90
136
Ozone
2018
365
117
207
39
2
0
0
61
101
169
Ozone
2017
365
131
190
43
1
0
0
60
104
156
Ozone
2016
366
165
174
23
4
0
0
53
90
158
Ozone
2015
365
163
175
25
2
0
0
54
92
154
Ozone
2014
365
201
142
20
2
0
0
49
81
155
Ozone
2013
365
169
146
42
8
0
0
52
122
163
Ozone
2012
366
151
198
16
1
0
0
54
90
151
Ozone
2011
365
171
164
27
3
0
0
51
99
160
Ozone
2010
365
166
176
15
7
0
1
52
90
501
Ozone
2009
365
113
215
32
5
0
0
58
101
164
PM2.5
2008
366
102
231
28
5
0
0
58
97
160
PM2.5
2007
365
93
209
51
12
0
0
64
115
177
PM2.5
2006
365
112
199
49
5
0
0
61
108
161
PM2.5
2005
365
121
184
53
7
0
0
58
116
187
PM2.5
2004
366
111
200
34
21
0
0
61
116
178
PM2.5
2003
365
126
200
32
6
1
0
58
101
296
Ozone
2002
365
112
187
51
15
0
0
60
122
177
PM2.5
2001
365
96
215
36
17
1
0
59
119
204
PM2.5
2000
366
109
205
39
12
1
0
60
112
206
Ozone
1999
365
95
234
33
2
1
0
59
100
206
Ozone
1998
365
154
167
26
17
1
0
53
105
203
Ozone
1997
365
196
153
15
1
0
0
49
77
151
NO2
1996
366
176
144
38
7
1
0
51
103
206
NO2
1995
365
194
154
13
4
0
0
49
81
187
PM10
1994
365
147
172
36
10
0
0
55
109
172
PM10
1993
365
150
197
16
2
0
0
56
88
172
NO2
1992
366
166
179
21
0
0
0
53
90
123
Ozone
1991
365
182
148
34
1
0
0
51
100
159
Ozone
1990
365
216
138
11
0
0
0
46
74
147
Ozone
1989
365
130
194
37
4
0
0
57
102
190
NO2
1988
366
128
198
32
8
0
0
58
105
177
NO2
1987
365
127
211
25
1
0
1
57
97
370
NO2
1986
365
143
157
60
5
0
0
57
115
197
NO2
1985
365
136
178
41
6
4
0
58
106
247
NO2
1984
366
154
163
41
6
2
0
57
103
209
NO2
1983
365
195
142
17
11
0
0
49
95
192
CO
1982
365
121
203
31
10
0
0
59
106
192
CO
1981
365
155
160
41
9
0
0
57
108
182
NO2
1980
366
120
159
66
15
6
0
68
126
238
Ozone
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
