Los Angeles County, California air quality history
Daily Air Quality Index summaries from EPA monitors in Los Angeles, California, 1980–2025.
11%
Good days in 2025
74
Median daily AQI, 2025
98
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 Los Angeles, California on 365 days. 39 of those days (11%) were in the Good range, and the median daily AQI was 74. 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 193 days. Across the years with fuller monitoring, the share of Good days rose: an average of 2% in 1980–1982 versus 11% 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
193
53%
Fine particles (PM2.5)
151
41%
Coarse particles (PM10)
15
4%
Nitrogen dioxide (NO₂)
6
2%
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
228
66
31
1
0
74
147
201
Ozone
2024
366
38
195
78
46
9
0
80
164
230
Ozone
2023
365
41
237
52
32
3
0
67
147
210
PM2.5
2022
365
17
254
65
28
1
0
74
140
209
Ozone
2021
365
9
259
70
26
1
0
79
143
281
PM2.5
2020
366
35
194
77
43
17
0
85
166
250
Ozone
2019
365
34
245
57
28
1
0
72
136
201
PM2.5
2018
365
7
250
89
18
1
0
78
130
201
PM2.5
2017
365
9
237
73
38
8
0
79
156
224
PM2.5
2016
366
7
255
81
19
4
0
77
134
226
PM2.5
2015
365
3
230
95
36
1
0
80
151
203
PM2.5
2014
365
8
250
79
26
2
0
82
143
205
PM2.5
2013
365
8
257
75
25
0
0
79
140
197
PM2.5
2012
366
14
222
93
35
2
0
84
151
207
PM2.5
2011
365
2
242
82
36
3
0
80
151
218
PM2.5
2010
365
14
237
99
15
0
0
78
138
200
PM2.5
2009
365
19
228
71
43
4
0
80
156
218
PM2.5
2008
366
12
233
67
46
8
0
84
172
227
PM2.5
2007
365
24
214
91
30
6
0
82
150
213
PM2.5
2006
365
32
204
79
39
11
0
83
163
224
Ozone
2005
365
36
191
77
48
13
0
84
166
238
Ozone
2004
366
15
193
87
67
4
0
90
169
229
PM2.5
2003
365
22
173
83
57
30
0
96
197
249
Ozone
2002
365
22
164
104
53
22
0
99
179
241
PM2.5
2001
365
13
166
127
48
11
0
101
163
230
PM2.5
2000
366
15
176
114
51
10
0
99
161
243
PM2.5
1999
365
17
180
140
27
1
0
97
140
203
NO2
1998
365
54
193
72
22
24
0
77
172
269
NO2
1997
365
33
171
116
32
13
0
95
154
226
Ozone
1996
366
42
154
91
47
32
0
96
192
247
Ozone
1995
365
44
107
109
45
60
0
107
212
256
Ozone
1994
365
22
124
96
41
82
0
107
221
292
Ozone
1993
365
29
108
111
45
72
0
108
221
284
Ozone
1992
366
22
104
92
59
89
0
122
232
300
Ozone
1991
365
16
118
95
51
84
1
116
233
696
Ozone
1990
365
17
119
84
56
89
0
116
229
276
Ozone
1989
365
10
69
110
63
113
0
150
248
295
Ozone
1988
366
9
65
84
63
145
0
168
255
298
Ozone
1987
365
6
92
86
52
129
0
150
247
293
Ozone
1986
365
7
72
92
54
140
0
156
268
300
Ozone
1985
365
10
82
91
43
139
0
150
268
298
Ozone
1984
366
5
71
101
52
137
0
154
263
300
Ozone
1983
365
11
103
79
37
135
0
143
280
300
Ozone
1982
365
8
83
91
54
129
0
151
265
300
Ozone
1981
365
4
56
99
46
160
0
176
268
300
Ozone
1980
366
6
73
81
47
156
3
168
278
386
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
