Downtown Los Angeles skyline looking northeast. Los Angeles Almanac Photo.
As bad a reputation as Los Angeles County has had with air pollution (not undeserved in light of its history), it ranked in 2023 behind two dozen other U.S. counties with a higher number of unhealthy air quality days. These include Bannock County in Idaho, Riverside and San Bernardino Counties in California, and Uintah and Duchesne Counties in Utah.
The Air Quality Index Summary Report displays an annual summary of Air Quality Index (AQI) values for all U.S. counties. 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), as in all counties, measure some, but not all, of the pollutants.
COLUMN DESCRIPTIONS FOR TABLE 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.
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 |
---|---|---|---|---|---|---|
2023 | 92 | 186 | 52 | 32 | 3 | 87 |
2022 | 40 | 231 | 65 | 28 | 1 | 94 |
2021 | 41 | 228 | 70 | 26 | - | 96 |
2020† | 60 | 169 | 77 | 44 | 16 | 137 |
2019 | 66 | 213 | 57 | 28 | 1 | 86 |
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 |
2018 | 35 | 222 | 89 | 18 | 1 | 108 |
2017 | 38 | 207 | 74 | 38 | 8 | 120 |
2016† | 32 | 230 | 81 | 19 | 4 | 104 |
2015 | 26 | 207 | 95 | 36 | 1 | 132 |
2014 | 23 | 234 | 80 | 26 | 2 | 108 |
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 |
2013 | 22 | 243 | 75 | 25 | 0 | 100 |
2012† | 33 | 203 | 93 | 35 | 2 | 130 |
2011 | 17 | 227 | 82 | 36 | 3 | 121 |
2010 | 32 | 219 | 99 | 15 | 0 | 114 |
2009 | 34 | 213 | 71 | 43 | 4 | 118 |
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 |
2008† | 31 | 213 | 68 | 46 | 8 | 122 |
2007 | 45 | 193 | 91 | 30 | 6 | 127 |
2006 | 64 | 172 | 79 | 39 | 11 | 129 |
2005 | 57 | 170 | 77 | 49 | 12 | 138 |
2004† | 29 | 179 | 87 | 67 | 4 | 158 |
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 |
2003 | 41 | 154 | 83 | 57 | 30 | 170 |
2002 | 34 | 152 | 104 | 53 | 22 | 179 |
2001 | 20 | 159 | 127 | 48 | 11 | 186 |
2000† | 27 | 164 | 114 | 51 | 10 | 175 |
1999 | 17 | 180 | 140 | 27 | 1 | 168 |
Table continues after image below...
Smoggy versus clean air over Downtown Los Angeles. Undated photos. From The History of the California Environmental Protection Agency, courtesy of the California Environmental Protection Agency.
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 |
---|---|---|---|---|---|---|
1998 | 54 | 193 | 72 | 22 | 24 | 118 |
1997 | 33 | 171 | 116 | 32 | 13 | 161 |
1996† | 42 | 154 | 91 | 47 | 32 | 170 |
1995 | 43 | 108 | 109 | 45 | 60 | 214 |
1994 | 22 | 124 | 96 | 41 | 82 | 219 |
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 |
1993 | 29 | 108 | 111 | 45 | 72 | 228 |
1992† | 22 | 104 | 92 | 59 | 89 | 240 |
1991 | 16 | 117 | 96 | 51 | 85 | 232 |
1990 | 17 | 118 | 84 | 57 | 89 | 230 |
1989 | 10 | 69 | 110 | 63 | 113 | 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 |
1988† | 9 | 65 | 84 | 63 | 145 | 292 |
1987 | 6 | 91 | 87 | 52 | 129 | 268 |
1986 | 7 | 72 | 92 | 54 | 140 | 286 |
1985 | 10 | 82 | 91 | 43 | 139 | 273 |
1984† | 5 | 71 | 101 | 52 | 137 | 290 |
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 |
1983 | 11 | 102 | 80 | 37 | 135 | 252 |
1982 | 8 | 83 | 91 | 54 | 129 | 274 |
1981 | 4 | 56 | 99 | 46 | 160 | 305 |
1980† | 6 | 74 | 80 | 47 | 159 | 286 |
* Non-final statistics. Preliminary until May of following year.
† Leap year with 366 days.
Source: Air Quality Reports, U.S. Environmental Protection Agency