Jefferson County, IN radon potential

EPA's own radon map rates Jefferson County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. Nationally that's the 51st percentile for radon potential — Jefferson County outranks 51% of every county EPA has rated.

Jefferson County by the numbers

Jefferson County, Indiana is home to about 32,921 people across 360.699 square miles. Population density there runs about 91 people per square mile. Within its own EPA zone, Jefferson County is bigger by population than 55% of the counties that share it. Geologically, Jefferson County is grouped into EPA Region 5 alongside 523 other counties that share its rock and soil setting.

What this actually means for a house in Jefferson County

EPA's Zone 2 rating for Jefferson County sits below its own 4 pCi/L action level but above the national indoor average of about 1.3 pCi/L. A Zone 2 rating is a moderate county-wide average, not a guarantee about any one house in Jefferson County — testing is the only way to know an individual home's actual level.

Next steps for a home in Jefferson County

A short-term test kit is the standard first step and typically costs far less than mitigation itself. If a test comes back at or above 4 pCi/L, a radon mitigation system for a typical home runs roughly $800–$2,500 (around $1,200 for a common single-family install), driven mainly by foundation type, not by county.

Find Indiana's state radon program

For Jefferson County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Jefferson 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 Jefferson County's figures come from

The methodology guide shows exactly which EPA and Census sources feed Jefferson County's numbers. Whatever zone Jefferson County carries, the zone explainer covers what it does and doesn't tell you about any one house.