What EPA's radon map says about Dillon County

Dillon County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. Nationally, Dillon County ranks higher in radon potential than 17% of rated counties (the 17th percentile).

Where Dillon County sits nationally

About 27,577 people live in Dillon County, South Carolina, spread over 405.076 square miles. Averaged across its land area, Dillon County runs about 68 people per square mile. Among counties sharing Dillon County's EPA zone, it outranks 51% of them by population. Geologically, Dillon 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

Dillon County's Zone 3 prediction undercuts the roughly 1.3 pCi/L most US homes average, nowhere near EPA's 4 pCi/L threshold for recommending mitigation. A Zone 3 rating means Dillon County's county-wide average is predicted low, but EPA is explicit that a meaningful share of homes in low-potential zones still test above the action level — a low zone is not a reason to skip testing.

Next steps for a home in Dillon County

Mitigation cost doesn't depend on Dillon County's zone — it depends on the house's foundation. A typical system runs $800–$2,500 (about $1,200 typical), and testing first is what tells you whether that's needed at all.

Find South Carolina's state radon program

Dillon County's test kit answers today; a Airthings radon monitor keeps answering for Dillon 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

Dillon County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. Whatever zone Dillon County carries, the zone explainer covers what it does and doesn't tell you about any one house.