What EPA's radon map says about Cass County

Cass County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Nationally that's the 90th percentile for radon potential — Cass County outranks 90% of every county EPA has rated.

How Cass County compares

About 51,550 people live in Cass County, Michigan, spread over 490.129 square miles. That works out to roughly 105 people per square mile. Among counties sharing Cass County's EPA zone, it outranks 71% of them by population. EPA's geology-based Region 5 groups Cass County with 523 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Cass County

Cass 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 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

Mitigation cost doesn't depend on Cass 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 Michigan's state radon program

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

The methodology guide shows exactly which EPA and Census sources feed Cass County's numbers. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.