What EPA's radon map says about Montgomery County

Montgomery County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Montgomery County sits at the 88th percentile nationally for radon potential — above 88 of every 100 rated counties.

Where Montgomery County sits nationally

About 38,633 people live in Montgomery County, Indiana, spread over 504.627 square miles. That works out to roughly 77 people per square mile. Among counties sharing Montgomery County's EPA zone, it outranks 64% of them by population. Geologically, Montgomery County is grouped into EPA Region 5 alongside 523 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Montgomery County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. Being in Zone 1 raises the odds Montgomery County homes test above the action level, but it does not mean any specific house does — EPA recommends every home be tested, in every zone, because the only way to know is to test.

If Montgomery County tests above the action level

Mitigation cost doesn't depend on Montgomery 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

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

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.