What EPA's radon map says about McCormick County

McCormick 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 McCormick County lands in the 7th percentile for radon potential.

McCormick County by the numbers

About 9,983 people live in McCormick County, South Carolina, spread over 358.89 square miles. Averaged across its land area, McCormick County runs about 28 people per square mile. Among counties sharing McCormick County's EPA zone, it outranks 20% of them by population. Geologically, McCormick County is grouped into EPA Region 4 alongside 735 other counties that share its rock and soil setting.

Zone vs. an actual test

Well clear of both the 1.3 pCi/L national indoor average and EPA's 4 pCi/L action level, McCormick County's Zone 3 prediction is the low end of the scale. Don't read Zone 3 as a pass for McCormick County — EPA's guidance to test every home makes no exception for counties predicted low.

Next steps for a home in McCormick County

Mitigation cost doesn't depend on McCormick 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

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

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