Worst Air Quality Days by County
The Air Quality Index on the county's dirtiest tenth of days. A place with clean air most of the year and a bad fire season shows it here rather than in the median.
See Worst Air Quality Days on the interactive map →
Highest counties
| County | Worst Air Quality Days |
|---|---|
| San Bernardino County, California | 185.0 |
| Riverside County, California | 174.0 |
| Los Angeles County, California | 164.0 |
| Tulare County, California | 147.0 |
| Kern County, California | 140.0 |
| Boise County, Idaho | 138.0 |
| Fresno County, California | 126.0 |
| Cameron County, Texas | 124.0 |
| Maricopa County, Arizona | 113.0 |
| El Paso County, Texas | 112.0 |
| Pinal County, Arizona | 111.0 |
| Cataño Municipio, Puerto Rico | 111.0 |
Lowest counties
| County | Worst Air Quality Days |
|---|---|
| Hopewell city, Virginia | 12.0 |
| Carroll County, Virginia | 14.0 |
| Karnes County, Texas | 16.0 |
| Uinta County, Wyoming | 17.0 |
| North Slope Borough, Alaska | 17.0 |
| Kenai Peninsula Borough, Alaska | 17.0 |
| Carbon County, Wyoming | 18.0 |
| Columbiana County, Ohio | 19.0 |
| San Juan County, Colorado | 19.0 |
| Wilson County, Texas | 20.0 |
| Navajo County, Arizona | 22.0 |
| Pacific County, Washington | 24.0 |