Daily Air Quality Index summaries from EPA monitors in Riverside, California, 1980–2025.
11%
Good days in 2025
80
Median daily AQI, 2025
109
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 Riverside, California on 365 days. 39 of those days (11%) were in the Good range, and the median daily AQI was 80. That median is higher than the typical monitored county in California (median 45.5 across 46 counties), and higher than the typical monitored U.S. county (40). The main pollutant was ozone on 207 days. Across the years with fuller monitoring, the share of Good days held roughly steady: an average of 13% in 1980–1982 versus 13% 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
207
57%
Fine particles (PM2.5)
121
33%
Coarse particles (PM10)
37
10%
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
39
217
75
33
0
1
80
150
365
Ozone
2024
366
43
176
80
60
7
0
87
174
213
Ozone
2023
365
62
189
73
31
6
4
77
154
660
Ozone
2022
365
41
198
86
31
2
7
77
151
1683
Ozone
2021
365
19
210
89
44
2
1
89
158
329
Ozone
2020
366
42
179
98
36
9
2
87
159
584
Ozone
2019
365
53
192
91
29
0
0
77
147
185
Ozone
2018
365
32
193
102
32
6
0
87
153
296
Ozone
2017
365
26
188
100
43
6
2
87
161
359
Ozone
2016
366
23
214
86
37
4
2
83
154
379
Ozone
2015
365
19
206
106
32
2
0
88
150
238
Ozone
2014
365
11
198
122
32
1
1
93
150
541
Ozone
2013
365
19
210
98
36
0
2
88
151
450
Ozone
2012
366
10
189
113
53
1
0
94
156
233
Ozone
2011
365
15
195
96
50
8
1
93
164
318
Ozone
2010
365
11
208
95
48
3
0
87
156
217
Ozone
2009
365
12
205
90
56
2
0
87
164
204
Ozone
2008
366
23
189
90
49
14
1
92
179
320
Ozone
2007
365
46
136
115
60
7
1
101
163
1176
Ozone
2006
365
57
164
79
54
11
0
84
174
218
Ozone
2005
365
49
159
89
53
15
0
91
172
228
Ozone
2004
366
45
144
93
67
17
0
99
175
212
Ozone
2003
365
32
167
68
70
28
0
97
195
243
Ozone
2002
365
32
149
87
74
23
0
101
185
226
Ozone
2001
365
30
134
99
77
24
1
110
187
500
PM2.5
2000
366
39
138
101
76
12
0
103
174
222
Ozone
1999
365
51
145
101
62
6
0
96
166
219
Ozone
1998
365
97
133
69
33
33
0
77
197
267
Ozone
1997
365
87
114
62
70
32
0
89
200
245
Ozone
1996
366
88
126
65
47
40
0
87
203
260
Ozone
1995
365
82
112
71
47
53
0
93
206
259
Ozone
1994
365
78
113
52
53
69
0
97
214
263
Ozone
1993
365
88
101
50
55
71
0
100
222
295
Ozone
1992
366
82
87
59
56
82
0
105
222
293
Ozone
1991
365
63
104
62
62
74
0
105
227
296
Ozone
1990
365
60
112
66
48
78
1
103
223
407
Ozone
1989
365
47
97
66
48
105
2
126
229
620
Ozone
1988
366
72
84
58
52
100
0
119
232
293
Ozone
1987
365
77
96
43
47
102
0
105
235
285
Ozone
1986
365
63
116
41
52
93
0
103
233
284
Ozone
1985
365
80
85
44
40
116
0
108
253
300
Ozone
1984
366
52
116
40
52
106
0
110
243
300
Ozone
1983
365
83
110
35
31
106
0
100
249
296
Ozone
1982
365
74
103
48
41
99
0
103
238
300
Ozone
1981
365
35
82
80
40
128
0
136
253
300
Ozone
1980
366
37
115
58
31
125
0
114
269
300
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 California with a similar median AQI in 2025
