Sullivan County, IN radon potential

EPA places Sullivan 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. Rank it against the rest of the country and Sullivan County lands in the 46th percentile for radon potential.

Sullivan County by the numbers

Sullivan County, Indiana is home to about 20,768 people across 447.196 square miles. Population density there runs about 46 people per square mile. Within its own EPA zone, Sullivan County is bigger by population than 41% of the counties that share it. Geologically, Sullivan County is grouped into EPA Region 5 alongside 523 other counties that share its rock and soil setting.

Zone vs. an actual test

Sullivan 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. A county-wide moderate average, like Sullivan County's, can still hide a specific house well above or below it — testing is what actually answers the question.

Next steps for a home in Sullivan 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 Sullivan County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Sullivan County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. Code RADONZONE-10OFF takes 10% off at checkout.

Where Sullivan 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 Sullivan County carries, the zone explainer covers what it does and doesn't tell you about any one house.