Is Montgomery County, IL a radon risk area?

Montgomery 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. Nationally, Montgomery County ranks higher in radon potential than 50% of rated counties (the 50th percentile).

Montgomery County by the numbers

About 27,615 people live in Montgomery County, Illinois, spread over 703.766 square miles. That works out to roughly 39 people per square mile. Rank 511 by population within its EPA zone puts Montgomery County at the 51st percentile among zone peers. EPA's geology-based Region 5 groups Montgomery County with 523 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

Montgomery 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. A Zone 2 rating is a moderate county-wide average, not a guarantee about any one house in Montgomery County — testing is the only way to know an individual home's actual level.

Next steps for a home in Montgomery County

Nothing about Montgomery 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 Illinois's state radon program

Montgomery County's test kit answers today; a Airthings radon monitor keeps answering for Montgomery 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 Montgomery County's numbers. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.