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Air quality in South Carolina

EPA monitors report from 14 of South Carolina’s 46 counties. That is the honest limit of this page: the other 32 are not measured, not clean. In 2025 the most affected monitored county was Horry County, with 3 days above the moderate category.

14
Counties with monitors
32
Counties without
6
Days above moderate, 2025
Summed across monitored counties
9.6%
Adults with asthma
Population-weighted county estimate

County by county

Monitored South Carolina counties

GoodModerateUnhealthy for sensitive groupsUnhealthyVery unhealthyHazardous
County90th %ile AQIAbove moderateMax AQI2025 days by category
Horry County553170
Charleston County591105
Chesterfield County581103
Florence County581108
Aiken County50071
Anderson County50084
Berkeley County48084
Darlington County51097
Edgefield County60098
Greenville County64093
Lexington County58077
Richland County61089
Spartanburg County62093
York County58093

EPA Air Quality System annual summaries by county, 2025. The 90th percentile AQI describes a day worse than nine out of ten, which is a steadier measure than the annual maximum a single wildfire can set.

Not measured

32 counties without a monitor

No EPA monitor reported from these counties, so there is no air quality record to publish. Their radon zone is known, and radon is measured in the building rather than the air outside it.

Other states

Air quality elsewhere