What EPA's radon map says about Warren County

EPA's own radon map rates Warren County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Nationally that's the 74th percentile for radon potential — Warren County outranks 74% of every county EPA has rated.

Where Warren County sits nationally

About 8,451 people live in Warren County, Indiana, spread over 364.685 square miles. Population density there runs about 23 people per square mile. Among counties sharing Warren County's EPA zone, it outranks 24% of them by population. EPA's geology-based Region 5 groups Warren County with 523 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

Fixing a home becomes an EPA recommendation past 4 pCi/L, and that is precisely the side of the line Warren County's Zone 1 prediction lands on, well above the roughly 1.3 pCi/L most US homes average. That doesn't mean every Warren 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 Warren County tests above the action level

Mitigation cost doesn't depend on Warren 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 Indiana's state radon program

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

Warren County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.