What EPA's radon map says about Jo Daviess County

EPA places Jo Daviess County in Zone 1 - Highest Potential — a predicted county-wide average indoor radon level above 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. That puts Jo Daviess County in the 83rd percentile nationally for radon potential — higher than 83% of the counties EPA has rated.

Jo Daviess County by the numbers

About 21,528 people live in Jo Daviess County, Illinois, spread over 600.924 square miles. Averaged across its land area, Jo Daviess County runs about 36 people per square mile. Among counties sharing Jo Daviess County's EPA zone, it outranks 49% of them by population. EPA's geology-based Region 5 groups Jo Daviess County with 523 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Jo Daviess County

Where the national indoor average runs about 1.3 pCi/L, Jo Daviess County's Zone 1 rating puts its predicted county average above EPA's 4 pCi/L action level itself. Some Jo Daviess County homes will test comfortably under the action level despite the county's Zone 1 rating — the only way to know which kind of home you have is an actual test.

Next steps for a home in Jo Daviess County

Mitigation cost doesn't depend on Jo Daviess 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

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

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. Whatever zone Jo Daviess County carries, the zone explainer covers what it does and doesn't tell you about any one house.