Gibson County, IN: EPA's radon zone, explained

EPA places Gibson County in Zone 2 - Moderate Potential — a predicted county-wide average indoor radon level between 2 and 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Nationally that's the 51st percentile for radon potential — Gibson County outranks 51% of every county EPA has rated.

Gibson County by the numbers

Gibson County, Indiana is home to about 33,038 people across 487.378 square miles. Population density there runs about 68 people per square mile. By population, Gibson County is the 461st largest of every county sharing its EPA zone — the 55th percentile by population within that zone. Gibson County falls in EPA Radon Region 5, one of 524 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

Gibson County's Zone 2 prediction clears the 1.3 pCi/L national indoor average without reaching EPA's own 4 pCi/L point for recommending a fix. Nothing about a Zone 2 label lowers the case for testing in Gibson County — EPA recommends it in every zone, moderate included.

If Gibson County tests above the action level

For a Gibson 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 Indiana's state radon program

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

Where Gibson 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. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.