What EPA's radon map says about Hancock County

Hancock 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 Hancock County in the 80th percentile nationally for radon potential — higher than 80% of the counties EPA has rated.

How Hancock County compares

About 17,008 people live in Hancock County, Illinois, spread over 793.748 square miles. Averaged across its land area, Hancock County runs about 21 people per square mile. Among counties sharing Hancock County's EPA zone, it outranks 42% of them by population. Geologically, Hancock County is grouped into EPA Region 5 alongside 523 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

Hancock 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. A Zone 1 rating means testing is worth doing sooner rather than later, but it is still county-wide average, not a reading for any single house — some homes in Hancock County will test well under the action level, and EPA's guidance is to test regardless of zone.

If Hancock County tests above the action level

Mitigation cost doesn't depend on Hancock 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

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

Hancock 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.