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Annual Air Quality
Los Angeles County

Air Quality Days by Year, 1980 - 2019

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

Downtown Los Angeles slyline looking northeast. Los Angeles Almanac Photo.


Also see: U.S. Counties with Highest Number of Unhealthy Air Quality Days


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.

All years measured over 365 days, except Leap Years (marked with asterisk in table), measured over 366 days.

Year Good Quality Air Days Moderate Quality Air Days Unhealthy Air for Sensitive Groups Unhealthy Air Days Very Unhealthy Air Days
2019 66 213 57 28 1
2018 35 222 89 18 1
2017 38 207 74 38 8
2016* 32 230 81 19 4
2015 26 207 95 36 1
2014 23 234 80 26 2
2013 22 243 75 25 0
2012* 33 203 93 35 2
Year Good Quality Air Days Moderate Quality Air Days Unhealthy Air for Sensitive Groups Unhealthy Air Days Very Unhealthy Air Days
2011 17 227 82 36 3
2010 32 219 99 15 0
2009 34 213 71 43 4
2008* 31 213 68 46 8
2007 45 193 91 30 6
2006 64 172 79 39 11
2005 57 170 77 49 12
2004* 29 179 87 67 4
Year Good Quality Air Days Moderate Quality Air Days Unhealthy Air for Sensitive Groups Unhealthy Air Days Very Unhealthy Air Days
2003 41 154 83 57 30
2002 34 152 104 53 22
2001 20 159 127 48 11
2000* 27 164 114 51 10
1999 17 180 140 27 1
1998 54 193 72 22 24
1997 33 171 116 32 13
1996* 42 154 91 47 32
Year Good Quality Air Days Moderate Quality Air Days Unhealthy Air for Sensitive Groups Unhealthy Air Days Very Unhealthy Air Days
1995 43 108 109 45 60
1994 22 124 96 41 82
1993 29 108 111 45 72
1992* 22 104 92 59 89
1991 16 117 96 51 85
1990 17 118 84 57 89
1989 10 69 110 63 113
Year Good Quality Air Days Moderate Quality Air Days Unhealthy Air for Sensitive Groups Unhealthy Air Days Very Unhealthy Air Days
1988* 9 65 84 63 145
1987 6 91 87 52 129
1986 7 72 92 54 140
1985 10 82 91 43 139
1984* 5 71 101 52 137
1983 11 102 80 37 135
1982 8 83 91 54 129
1981 4 56 99 46 160
1980* 6 74 80 47 159

* Leap year with 366 days.

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 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 Air Days - Number of days in the year when the Air Quality Index (AQI) value is 201 or higher.Health alert: 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.

Source: U.S. Environmental Protection Agency