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Annual Air Quality
Los Angeles County

Air Quality Days by Year, 1980 - 2023

Downtown Los Angeles Skyline as Seen From First AME Church, 2019

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...


Air Quality, Los Angeles

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.


Table continues from above...
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