What EPA's radon map says about Ionia County

Ionia County is mapped as Zone 2 - Moderate Potential by EPA — meaning the county-wide average indoor level is predicted between 2 and 4 pCi/L. That puts Ionia County in the 57th percentile nationally for radon potential — higher than 57% of the counties EPA has rated.

How Ionia County compares

About 66,250 people live in Ionia County, Michigan, spread over 571.32 square miles. That works out to roughly 116 people per square mile. Among counties sharing Ionia County's EPA zone, it outranks 73% of them by population. EPA's geology-based Region 5 groups Ionia County with 523 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Ionia County

Ionia County's Zone 2 prediction clears the 1.3 pCi/L national indoor average without reaching EPA's own 4 pCi/L point for recommending a fix. Ionia County's Zone 2 rating sits in the middle nationally; EPA's guidance is unchanged by that — test every home regardless of its zone.

Testing and mitigation in Ionia County

Mitigation cost doesn't depend on Ionia 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

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

Ionia County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. Whatever zone Ionia County carries, the zone explainer covers what it does and doesn't tell you about any one house.