What EPA's radon map says about Copiah County

EPA's own radon map rates Copiah County zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. Nationally that's the 17th percentile for radon potential — Copiah County outranks 17% of every county EPA has rated.

Copiah County by the numbers

About 27,536 people live in Copiah County, Mississippi, spread over 777.285 square miles. Averaged across its land area, Copiah County runs about 35 people per square mile. Among counties sharing Copiah County's EPA zone, it outranks 50% of them by population. EPA's geology-based Region 4 groups Copiah County with 735 other counties nationally sharing its underlying rock and soil profile.

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, Copiah County's Zone 3 prediction is the low end of the scale. Don't read Zone 3 as a pass for Copiah County — EPA's guidance to test every home makes no exception for counties predicted low.

Next steps for a home in Copiah County

Mitigation cost doesn't depend on Copiah 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 Mississippi's state radon program

Copiah County's test kit answers today; a Airthings radon monitor keeps answering for Copiah County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

More on how this number was built

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