Daily Air Quality Index summaries from EPA monitors in Nevada, California, 1990–2025.
80%
Good days in 2025
42
Median daily AQI, 2025
1
Days above 100 in 2025
362
Days with an AQI in 2025 (of 365)
In 2025, EPA reported a daily Air Quality Index (AQI) for Nevada, California on 362 days. 289 of those days (80%) were in the Good range, and the median daily AQI was 42. That median is lower than the typical monitored county in California (median 45.5 across 46 counties), and about the same as the typical monitored U.S. county (40). The main pollutant was ozone on 250 days. Across the years with fuller monitoring, the share of Good days rose: an average of 62% in 1990–1992 versus 81% 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
250
69%
Fine particles (PM2.5)
112
31%
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
362
289
72
1
0
0
0
42
58
108
Ozone
2024
365
313
50
2
0
0
0
36
55
132
PM2.5
2023
363
282
81
0
0
0
0
42
55
97
PM2.5
2022
365
185
161
11
3
5
0
50
87
293
Ozone
2021
365
183
129
34
13
4
2
50
115
326
Ozone
2020
366
223
111
15
11
6
0
46
91
277
PM2.5
2019
361
251
105
5
0
0
0
45
71
122
Ozone
2018
363
231
104
19
7
2
0
45
87
218
Ozone
2017
365
194
90
62
19
0
0
49
133
185
Ozone
2016
366
232
89
40
5
0
0
45
101
179
Ozone
2015
364
213
120
29
2
0
0
48
93
166
Ozone
2014
365
211
120
33
1
0
0
47
100
168
Ozone
2013
362
202
139
21
0
0
0
48
92
140
Ozone
2012
366
226
112
26
2
0
0
43
97
164
Ozone
2011
365
233
111
20
1
0
0
44
87
154
Ozone
2010
365
242
101
21
1
0
0
44
90
154
Ozone
2009
364
232
96
34
2
0
0
44
100
164
Ozone
2008
366
173
141
34
17
1
0
52
115
203
Ozone
2007
365
86
218
52
9
0
0
61
119
177
Ozone
2006
365
166
116
59
24
0
0
54
136
200
Ozone
2005
365
181
120
44
18
2
0
51
126
216
Ozone
2004
366
161
133
60
11
1
0
54
122
206
Ozone
2003
365
163
109
71
22
0
0
58
133
195
Ozone
2002
365
167
110
62
23
3
0
54
140
208
Ozone
2001
365
156
139
50
19
1
0
56
129
201
Ozone
2000
366
152
126
63
22
3
0
58
136
208
Ozone
1999
365
129
140
68
28
0
0
67
143
195
Ozone
1998
365
187
102
54
22
0
0
50
133
185
Ozone
1997
365
99
183
68
15
0
0
67
129
190
Ozone
1996
366
198
74
67
27
0
0
48
140
197
Ozone
1995
303
194
80
26
3
0
0
44
100
166
Ozone
1994
359
232
88
31
7
1
0
44
101
202
Ozone
1993
229
214
15
0
0
0
0
38
48
90
Ozone
1992
311
206
69
34
2
0
0
42
105
154
Ozone
1991
363
226
98
34
5
0
0
44
101
177
Ozone
1990
214
126
52
27
7
2
0
46
119
210
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
