Greenville County, SC radon potential

EPA's own radon map rates Greenville County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Nationally, Greenville County ranks higher in radon potential than 99% of rated counties (the 99th percentile).

Where Greenville County sits nationally

Greenville County, South Carolina is home to about 570,745 people across 785.944 square miles. Averaged across its land area, Greenville County runs about 726 people per square mile. Within its own EPA zone, Greenville County is bigger by population than 97% of the counties that share it. EPA's geology-based Region 4 groups Greenville County with 735 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

Greenville County's predicted average sits above EPA's own action level of 4 pCi/L — the concentration at which EPA recommends fixing a home — versus a national average around 1.3 pCi/L indoors and 0.4 pCi/L outdoors. That doesn't mean every Greenville County house tests high — a zone is a county-wide prediction, never a single-home reading — but it's a reason to test sooner rather than let it wait.

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

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. Whatever zone Greenville County carries, the zone explainer covers what it does and doesn't tell you about any one house.