What EPA's radon map says about Montgomery County

EPA places Montgomery County in Zone 1 - Highest Potential — a predicted county-wide average indoor radon level above 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Nationally, Montgomery County ranks higher in radon potential than 99% of rated counties (the 99th percentile).

How Montgomery County compares

About 537,443 people live in Montgomery County, Ohio, spread over 461.352 square miles. Averaged across its land area, Montgomery County runs about 1,165 people per square mile. Among counties sharing Montgomery County's EPA zone, it outranks 96% of them by population. EPA's geology-based Region 5 groups Montgomery County with 523 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

Montgomery County carries a Zone 1 label because its predicted average clears 4 pCi/L outright — three-plus times the 0.4 pCi/L typical outdoors and above the 1.3 pCi/L most homes see. Some Montgomery County homes will test comfortably under the action level despite the county's Zone 1 rating — the only way to know which kind of home you have is an actual test.

Next steps for a home in Montgomery County

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 Ohio'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. Code RADONZONE-10OFF takes 10% off at checkout.

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.