Days with unhealthy air (% of days measured) by US counties, 2026
Unhealthy air days — Environment, a map app on Mappit.
Highest: Los Angeles County, CA 15.0%, Riverside County, CA 15.0%, San Bernardino County, CA 14.0%, Imperial County, CA 12.1%, El Paso County, TX 11.0%.
Lowest: San Juan Municipio, PR 0.0%, Ponce Municipio, PR 0.0%, Guaynabo Municipio, PR 0.0%, Guayama Municipio, PR 0.0%, Fajardo Municipio, PR 0.0%.
Biggest rises since 2025: Coffee County, GA +5.8 pts (0.0% to 5.8%), Bibb County, GA +5.5 pts (0.3% to 5.8%), Harrison County, TX +4.4 pts (0.0% to 4.4%).
Biggest falls since 2025: San Bernardino County, CA -16.1 pts (30.1% to 14.0%), Riverside County, CA -14.9 pts (29.9% to 15.0%), Los Angeles County, CA -11.8 pts (26.8% to 15.0%).
1,015 US counties with data; median 0.0%. 226 show their latest earlier value (up to five years old). 789 values preliminary.
Source: US Environmental Protection Agency, AirData annual AQI by county (Public domain (US federal work)). Figures updated 23 October 2026.
More from Environment.