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

EPA places Knox 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 Knox County lands in the 52nd percentile for radon potential.

How Knox County compares

Knox County, Indiana is home to about 35,872 people across 515.831 square miles. Population density there runs about 70 people per square mile. By population, Knox County is the 434th largest of every county sharing its EPA zone — the 58th percentile by population within that zone. EPA's geology-based Region 5 groups Knox County with 523 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Knox County

Knox 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. Middle-of-the-pack doesn't mean risk-free for any one Knox County address — a moderate county average still leaves individual homes to test either side of it.

Next steps for a home in Knox County

For a Knox 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 Knox County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Knox 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 Knox 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. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.