Is Florence County, SC a radon risk area?

Florence County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. Nationally, Florence County ranks higher in radon potential than 27% of rated counties (the 27th percentile).

How Florence County compares

About 138,049 people live in Florence County, South Carolina, spread over 800.454 square miles. Averaged across its land area, Florence County runs about 172 people per square mile. Rank 176 by population within its EPA zone puts Florence County at the 83rd percentile among zone peers. Geologically, Florence County is grouped into EPA Region 4 alongside 735 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

A Zone 3 county like Florence County is predicted closer to the 0.4 pCi/L typical outdoors than to EPA's 4 pCi/L action level. Don't read Zone 3 as a pass for Florence County — EPA's guidance to test every home makes no exception for counties predicted low.

Testing and mitigation in Florence County

Nothing about Florence County's EPA zone changes the mitigation number: $800–$2,500 nationally (around $1,200 typical), set by the house's foundation rather than the county it sits in — and only relevant once a test actually clears 4 pCi/L.

Find South Carolina's state radon program

Florence County's test kit answers today; a Airthings radon monitor keeps answering for Florence County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

More on how this number was built

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.