Is Miami County, IN a radon risk area?

EPA places Miami 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. Rank it against the rest of the country and Miami County lands in the 87th percentile for radon potential.

Miami County by the numbers

About 35,613 people live in Miami County, Indiana, spread over 373.842 square miles. Population density there runs about 95 people per square mile. Rank 419 by population within its EPA zone puts Miami County at the 61st percentile among zone peers. Geologically, Miami County is grouped into EPA Region 5 alongside 523 other counties that share its rock and soil setting.

What this actually means for a house in Miami County

Where the national indoor average runs about 1.3 pCi/L, Miami County's Zone 1 rating puts its predicted county average above EPA's 4 pCi/L action level itself. A Zone 1 rating means testing is worth doing sooner rather than later, but it is still county-wide average, not a reading for any single house — some homes in Miami County will test well under the action level, and EPA's guidance is to test regardless of zone.

Next steps for a home in Miami County

Nothing about Miami County's EPA zone changes the mitigation number: $800–$2,500 nationally (around $1,200 typical), set by the house's foundation rather than the county it sits in — and only relevant once a test actually clears 4 pCi/L.

Find Indiana's state radon program

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

The methodology guide shows exactly which EPA and Census sources feed Miami County's numbers. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.