Median Air Quality Index by County
The middle day of the year on the EPA's Air Quality Index. Below 50 is the range the EPA calls good; above 100 is unhealthy for sensitive groups.
See Median Air Quality Index on the interactive map →
Highest counties
| County | Median Air Quality Index |
|---|---|
| Riverside County, California | 87.0 |
| San Bernardino County, California | 87.0 |
| Los Angeles County, California | 80.0 |
| Maricopa County, Arizona | 77.0 |
| Pinal County, Arizona | 77.0 |
| Kern County, California | 72.0 |
| San Diego County, California | 71.0 |
| Tulare County, California | 71.0 |
| Fresno County, California | 67.0 |
| El Paso County, Texas | 67.0 |
| Clark County, Nevada | 64.0 |
| Imperial County, California | 63.0 |
Lowest counties
| County | Median Air Quality Index |
|---|---|
| Ponce Municipio, Puerto Rico | 3.0 |
| Caguas Municipio, Puerto Rico | 3.0 |
| Rosebud County, Montana | 4.0 |
| North Slope Borough, Alaska | 5.0 |
| Hopewell city, Virginia | 6.0 |
| Custer County, Idaho | 6.0 |
| Uinta County, Wyoming | 7.0 |
| Carroll County, Virginia | 7.0 |
| Wilson County, Texas | 7.0 |
| Karnes County, Texas | 7.0 |
| Washakie County, Wyoming | 8.0 |
| Carbon County, Wyoming | 8.0 |