Is Calhoun County, MI a radon risk area?

Calhoun County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Rank it against the rest of the country and Calhoun County lands in the 95th percentile for radon potential.

Calhoun County by the numbers

About 133,785 people live in Calhoun County, Michigan, spread over 706.259 square miles. Averaged across its land area, Calhoun County runs about 189 people per square mile. Rank 150 by population within its EPA zone puts Calhoun County at the 86th percentile among zone peers. EPA's geology-based Region 5 groups Calhoun County with 523 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

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

Testing and mitigation in Calhoun County

Nothing about Calhoun 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 Michigan's state radon program

Calhoun County's test kit answers today; a Airthings radon monitor keeps answering for Calhoun County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

More on how this number was built

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