Barnwell County, SC radon potential

EPA's own radon map rates Barnwell County zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. Nationally, Barnwell County ranks higher in radon potential than 14% of rated counties (the 14th percentile).

How Barnwell County compares

Barnwell County, South Carolina is home to about 20,495 people across 548.383 square miles. Population density there runs about 37 people per square mile. Within its own EPA zone, Barnwell County is bigger by population than 41% of the counties that share it. Barnwell 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

Barnwell 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. Low doesn't mean zero: EPA's own data shows homes in Zone 3 counties like Barnwell County testing above the action level often enough that skipping a test isn't the safe assumption.

Next steps for a home in Barnwell County

A short-term test kit is the standard first step and typically costs far less than mitigation itself. If a test comes back at or above 4 pCi/L, a radon mitigation system for a typical home runs roughly $800–$2,500 (around $1,200 for a common single-family install), driven mainly by foundation type, not by county.

Find South Carolina's state radon program

For Barnwell County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Barnwell County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. Use code RADONZONE-10OFF at checkout for 10% off.

Where Barnwell County's figures come from

The methodology guide shows exactly which EPA and Census sources feed Barnwell County's numbers. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.