Cass County, IN: EPA's radon zone, explained

EPA's own radon map rates Cass County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Cass County sits at the 87th percentile nationally for radon potential — above 87 of every 100 rated counties.

Cass County by the numbers

Cass County, Indiana is home to about 37,559 people across 412.144 square miles. Averaged across its land area, Cass County runs about 91 people per square mile. By population, Cass County is the 401st largest of every county sharing its EPA zone — the 62nd percentile by population within that zone. Geologically, Cass 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 Cass County

Where the national indoor average runs about 1.3 pCi/L, Cass County's Zone 1 rating puts its predicted county average above EPA's 4 pCi/L action level itself. Some Cass 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.

If Cass County tests above the action level

For a Cass County homeowner, the order is simple: test first, since a kit costs a small fraction of what mitigation would. Only if the result clears 4 pCi/L does a system — typically $800–$2,500, about $1,200 for a common install — become worth pricing out.

Find Indiana's state radon program

For Cass County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Cass County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. Code RADONZONE-10OFF takes 10% off at checkout.

Where Cass County's figures come from

The methodology guide shows exactly which EPA and Census sources feed Cass County's numbers. Whatever zone Cass County carries, the zone explainer covers what it does and doesn't tell you about any one house.