Is Edgar County, IL a radon risk area?

Edgar County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Nationally, Edgar County ranks higher in radon potential than 80% of rated counties (the 80th percentile).

Where Edgar County sits nationally

About 16,398 people live in Edgar County, Illinois, spread over 623.324 square miles. Population density there runs about 26 people per square mile. Rank 633 by population within its EPA zone puts Edgar County at the 41st percentile among zone peers. EPA's geology-based Region 5 groups Edgar County with 523 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Edgar County

Edgar County's predicted average sits above EPA's own action level of 4 pCi/L — the concentration at which EPA recommends fixing a home — versus a national average around 1.3 pCi/L indoors and 0.4 pCi/L outdoors. Being in Zone 1 raises the odds Edgar 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.

Next steps for a home in Edgar County

Nothing about Edgar 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

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

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