What EPA's radon map says about Menard County

Menard County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. That puts Menard County in the 77th percentile nationally for radon potential — higher than 77% of the counties EPA has rated.

How Menard County compares

About 11,963 people live in Menard County, Illinois, spread over 314.391 square miles. Population density there runs about 38 people per square mile. Among counties sharing Menard County's EPA zone, it outranks 32% of them by population. Menard County falls in EPA Radon Region 5, one of 524 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

Menard 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. That doesn't mean every Menard County house tests high — a zone is a county-wide prediction, never a single-home reading — but it's a reason to test sooner rather than let it wait.

If Menard County tests above the action level

Mitigation cost doesn't depend on Menard 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 Illinois's state radon program

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

More on how this number was built

Menard County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.