Fulton County, IL: EPA's radon zone, explained

EPA's own radon map rates Fulton County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. That puts Fulton County in the 86th percentile nationally for radon potential — higher than 86% of the counties EPA has rated.

Where Fulton County sits nationally

Fulton County, Illinois is home to about 32,510 people across 865.694 square miles. Population density there runs about 38 people per square mile. By population, Fulton County is the 446th largest of every county sharing its EPA zone — the 58th percentile by population within that zone. Fulton County falls in EPA Radon Region 5, one of 524 counties nationally EPA assigns to that same geologic province.

What this actually means for a house in Fulton County

Where the national indoor average runs about 1.3 pCi/L, Fulton County's Zone 1 rating puts its predicted county average above EPA's 4 pCi/L action level itself. Being in Zone 1 raises the odds Fulton 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.

Testing and mitigation in Fulton County

For a Fulton County homeowner, the order is simple: test first, since a kit costs a small fraction of what mitigation would. Only if the result clears 4 pCi/L does a system — typically $800–$2,500, about $1,200 for a common install — become worth pricing out.

Find Illinois's state radon program

For Fulton County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Fulton County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

Where Fulton County's figures come from

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