Lancaster County, SC radon potential

EPA's own radon map rates Lancaster County zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. Nationally, Lancaster County ranks higher in radon potential than 26% of rated counties (the 26th percentile).

Lancaster County by the numbers

Lancaster County, South Carolina is home to about 111,652 people across 549.172 square miles. That works out to roughly 203 people per square mile. Within its own EPA zone, Lancaster County is bigger by population than 80% of the counties that share it. EPA's geology-based Region 4 groups Lancaster County with 735 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

At Zone 3, Lancaster County's predicted county average is under the national indoor average (~1.3 pCi/L) and well below EPA's 4 pCi/L action level — outdoor air nationally runs about 0.4 pCi/L for comparison. Low doesn't mean zero: EPA's own data shows homes in Zone 3 counties like Lancaster County testing above the action level often enough that skipping a test isn't the safe assumption.

If Lancaster County tests above the action level

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 Lancaster County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Lancaster 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 Lancaster County's figures come from

The methodology guide shows exactly which EPA and Census sources feed Lancaster County's numbers. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.