What EPA's radon map says about Allendale County

Allendale County is mapped as Zone 3 - Low Potential by EPA — meaning the county-wide average indoor level is predicted below 2 pCi/L. Rank it against the rest of the country and Allendale County lands in the 5th percentile for radon potential.

How Allendale County compares

About 7,551 people live in Allendale County, South Carolina, spread over 408.095 square miles. That works out to roughly 19 people per square mile. Among counties sharing Allendale County's EPA zone, it outranks 14% of them by population. Allendale County falls in EPA Radon Region 4, one of 736 counties nationally EPA assigns to that same geologic province.

Why the zone isn't the answer by itself

Well clear of both the 1.3 pCi/L national indoor average and EPA's 4 pCi/L action level, Allendale County's Zone 3 prediction is the low end of the scale. Low doesn't mean zero: EPA's own data shows homes in Zone 3 counties like Allendale County testing above the action level often enough that skipping a test isn't the safe assumption.

Testing and mitigation in Allendale County

Mitigation cost doesn't depend on Allendale 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

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

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