Is Calhoun County, SC a radon risk area?

Calhoun County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. That puts Calhoun County in the 10th percentile nationally for radon potential — higher than 10% of the counties EPA has rated.

Calhoun County by the numbers

About 14,249 people live in Calhoun County, South Carolina, spread over 381.146 square miles. Population density there runs about 37 people per square mile. Rank 725 by population within its EPA zone puts Calhoun County at the 30th percentile among zone peers. Geologically, Calhoun County is grouped into EPA Region 4 alongside 735 other counties that share its rock and soil setting.

Zone vs. an actual test

Well clear of both the 1.3 pCi/L national indoor average and EPA's 4 pCi/L action level, Calhoun County's Zone 3 prediction is the low end of the scale. Even at Zone 3, Calhoun County homes are not guaranteed a low reading — zone is a county-wide average, and EPA recommends testing every home regardless of zone.

If Calhoun County tests above the action level

Nothing about Calhoun 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

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

More on how this number was built

Calhoun County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.