Downtown Los Angeles skyline looking northeast. Los Angeles Almanac Photo.
During 2025, Los Angeles County ranked third among U.S. counties for number of unhealthy air quality days with air pollution. The neighboring California counties of San Bernardino and Riverside ranked first and second in the country.
The Air Quality Index Daily Values Report provides a daily summary of Air Quality Index (AQI) values for Los Angeles County (summarized in the table below by month). The Air Quality Index Summary Report summarizes the same for the county each year. The AQI is an indicator of overall air quality, taking into account all criteria air pollutants (such as ozone, NO2, PM2.5 and PM10) measured within the county. Although the AQI includes all available pollutant measurements, each of the 11 monitoring stations in Los Angeles County (located in Azusa, Compton, Glendora, Lancaster, LAX, Long Beach, Downtown Los Angeles, Pasadena, Reseda and Santa Clarita) measure some, but not all, of the pollutants.
COLUMN DESCRIPTIONS FOR TABLES BELOW:
Good Quality Air Days - Number of days in the year when the Air Quality Index (AQI) value is 0 through 50. Air quality is considered satisfactory, and air pollution poses little or no risk.
Moderate Quality Air Days - Number of days in the year when the Air Quality Index (AQI) value is 51 through 100. Air quality is acceptable; however, for some pollutants there may be a moderate health concern for a very small number of people who are unusually sensitive to air pollution.
Unhealthy Air for Sensitive Groups - Number of days in the year when the Air Quality Index (AQI) value is 100 through 150. Members of sensitive groups may experience health effects. The general public is not likely to be affected.
Unhealthy Air Days - Number of days in the year when the Air Quality Index (AQI) value is 151 through 150. Everyone may begin to experience health effects; members of sensitive groups may experience more serious health effects.
Very Unhealthy or Hazardous Air Days - Number of days in the year when the Air Quality Index (AQI) value is 201 or higher. A health alert is issued for the day. Everyone may experience more serious health effects. When the AQI exceeds 300, the air situation is considered hazardous, meriting a health emergency. The entire population is more likely to be affected.
Data for 2026 are considered preliminary until May 1, 2027. Data for 2025 are considered preliminary until May 1, 2026.
| Month | Good Quality Air Days | Moderate Quality Air Days | Unhealthy Air for Sensitive Groups | Unhealthy Air Days | Very Unhealthy or Hazardous Air Days | Total Unhealthy/ Hazardous Air Days |
|---|---|---|---|---|---|---|
| Feb 2026 | 6 | 21 | 1 | 0 | 0 | 1 |
| Jan 2026 | 3 | 28 | 0 | 0 | 0 | 0 |
| Dec 2025 | 3 | 25 | 3 | 0 | 0 | 3 |
| Nov 2025 | 3 | 25 | 1 | 0 | 0 | 1 |
| Oct 2025 | 4 | 27 | 0 | 0 | 0 | 0 |
| Month | Good Quality Air Days | Moderate Quality Air Days | Unhealthy Air for Sensitive Groups | Very Unhealthy or Hazardous Air Days | Very Unhealthy Air Days | Total Unhealthy/ Hazardous Air Days |
| Sep 2025 | 5 | 18 | 6 | 1 | 0 | 7 |
| Aug 2025 | 0 | 7 | 16 | 8 | 0 | 24 |
| Jul 2025 | 0 | 14 | 12 | 5 | 0 | 17 |
| Jun 2025 | 0 | 13 | 8 | 8 | 1 | 17 |
| May 2025 | 1 | 18 | 9 | 3 | 0 | 12 |
| Month | Good Quality Air Days | Moderate Quality Air Days | Unhealthy Air for Sensitive Groups | Unhealthy Air Days | Very Unhealthy or Hazardous Air Days | Total Unhealthy/ Hazardous Air Days |
| Apr 2025 | 5 | 21 | 4 | 0 | 0 | 4 |
| Mar 2025 | 9 | 22 | 0 | 0 | 0 | 0 |
| Feb 2025 | 6 | 21 | 1 | 0 | 0 | 1 |
Source: Air Quality Index Daily Values Report at U.S. Environmental Protection Agency
All years were measured over 365 days, except Leap Years (marked with obelus "†"), measured over 366 days.
| Year | Good Quality Air Days | Moderate Quality Air Days | Unhealthy Air for Sensitive Groups | Unhealthy Air Days | Very Unhealthy or Hazardous Air Days | Total Unhealthy/ Hazardous Air Days |
|---|---|---|---|---|---|---|
| 2025 | 39 | 233 | 63 | 29 | 1 | 93 |
| 2024† | 38 | 195 | 78 | 46 | 9 | 133 |
| 2023 | 41 | 237 | 52 | 32 | 3 | 87 |
| 2022 | 17 | 254 | 65 | 28 | 1 | 94 |
| 2021 | 9 | 259 | 70 | 26 | 1 | 97 |
| Year | Good Quality Air Days | Moderate Quality Air Days | Unhealthy Air for Sensitive Groups | Very Unhealthy or Hazardous Air Days | Very Unhealthy Air Days | Total Unhealthy/ Hazardous Air Days |
| 2020† | 35 | 194 | 77 | 43 | 17 | 137 |
| 2019 | 34 | 245 | 57 | 28 | 1 | 86 |
| 2018 | 7 | 250 | 89 | 18 | 1 | 108 |
| 2017 | 9 | 237 | 73 | 38 | 8 | 119 |
| 2016† | 7 | 255 | 81 | 19 | 4 | 104 |
| Year | Good Quality Air Days | Moderate Quality Air Days | Unhealthy Air for Sensitive Groups | Unhealthy Air Days | Very Unhealthy or Hazardous Air Days | Total Unhealthy/ Hazardous Air Days |
| 2015 | 3 | 230 | 95 | 36 | 1 | 132 |
| 2014 | 8 | 250 | 79 | 26 | 2 | 107 |
| 2013 | 8 | 257 | 75 | 25 | 0 | 100 |
| 2012† | 14 | 222 | 93 | 35 | 2 | 130 |
| 2011 | 2 | 242 | 82 | 36 | 3 | 121 |
| Year | Good Quality Air Days | Moderate Quality Air Days | Unhealthy Air for Sensitive Groups | Unhealthy Air Days | Very Unhealthy or Hazardous Air Days | Total Unhealthy/ Hazardous Air Days |
| 2010 | 14 | 237 | 99 | 15 | 0 | 114 |
| 2009 | 19 | 228 | 71 | 43 | 4 | 118 |
| 2008† | 12 | 233 | 67 | 46 | 8 | 121 |
| 2007 | 24 | 214 | 91 | 30 | 6 | 127 |
| 2006 | 32 | 204 | 79 | 39 | 11 | 129 |
| Year | Good Quality Air Days | Moderate Quality Air Days | Unhealthy Air for Sensitive Groups | Unhealthy Air Days | Very Unhealthy or Hazardous Air Days | Total Unhealthy/ Hazardous Air Days |
| 2005 | 36 | 191 | 77 | 48 | 13 | 138 |
| 2004† | 15 | 193 | 87 | 67 | 4 | 158 |
| 2003 | 22 | 173 | 83 | 57 | 30 | 170 |
| 2002 | 22 | 164 | 104 | 53 | 22 | 179 |
| 2001 | 13 | 166 | 127 | 48 | 11 | 186 |
| Year | Good Quality Air Days | Moderate Quality Air Days | Unhealthy Air for Sensitive Groups | Unhealthy Air Days | Very Unhealthy or Hazardous Air Days | Total Unhealthy/ Hazardous Air Days |
| 2000† | 15 | 176 | 114 | 51 | 10 | 175 |
| 1999 | 17 | 180 | 140 | 27 | 1 | 168 |
| 1998 | 54 | 193 | 72 | 22 | 24 | 118 |
| 1997 | 33 | 171 | 116 | 32 | 13 | 161 |
| 1996† | 42 | 154 | 91 | 47 | 32 | 170 |
| Year | Good Quality Air Days | Moderate Quality Air Days | Unhealthy Air for Sensitive Groups | Unhealthy Air Days | Very Unhealthy or Hazardous Air Days | Total Unhealthy/ Hazardous Air Days |
| 1995 | 44 | 107 | 109 | 45 | 60 | 214 |
| 1994 | 22 | 124 | 96 | 41 | 82 | 219 |
| 1993 | 29 | 108 | 111 | 45 | 72 | 228 |
| 1992† | 22 | 104 | 92 | 59 | 89 | 240 |
| 1991 | 16 | 118 | 95 | 51 | 85 | 231 |
| Year | Good Quality Air Days | Moderate Quality Air Days | Unhealthy Air for Sensitive Groups | Unhealthy Air Days | Very Unhealthy or Hazardous Air Days | Total Unhealthy/ Hazardous Air Days |
| 1990 | 17 | 119 | 84 | 56 | 89 | 229 |
| 1989 | 10 | 69 | 110 | 63 | 113 | 286 |
| 1988† | 9 | 65 | 84 | 63 | 145 | 292 |
| 1987 | 6 | 92 | 86 | 52 | 129 | 267 |
| 1986 | 7 | 72 | 92 | 54 | 140 | 286 |
| Year | Good Quality Air Days | Moderate Quality Air Days | Unhealthy Air for Sensitive Groups | Unhealthy Air Days | Very Unhealthy or Hazardous Air Days | Total Unhealthy/ Hazardous Air Days |
| 1985 | 10 | 82 | 91 | 43 | 139 | 273 |
| 1984† | 5 | 71 | 101 | 52 | 137 | 290 |
| 1983 | 11 | 103 | 79 | 37 | 135 | 251 |
| 1982 | 8 | 83 | 91 | 54 | 129 | 274 |
| 1981 | 4 | 56 | 99 | 46 | 160 | 305 |
| 1980† | 6 | 73 | 81 | 47 | 159 | 287 |
† Leap year with 366 days.
** Data posted for this year are considered preliminary until final report on May 1 of the following year. Until then, comparing reported values for this year with previous years may not be valid.
Source: Air Quality Reports, U.S. Environmental Protection Agency
