US counties by share of days unhealthy for sensitive groups or worse (US EPA AQI), 2015
Alpine County 51.6%, the highest of 1021 counties, 2015
- Under 0.3
- 0.3 to 0.8
- 0.8 to 1.7
- 1.7 and over
- No data
Boundaries: U.S. Census Bureau cartographic boundary files.