What EPA's radon map says about Shelby County

EPA places Shelby County in Zone 1 - Highest Potential — a predicted county-wide average indoor radon level above 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Shelby County sits at the 89th percentile nationally for radon potential — above 89 of every 100 rated counties.

Shelby County by the numbers

About 45,654 people live in Shelby County, Indiana, spread over 411.136 square miles. Population density there runs about 111 people per square mile. Among counties sharing Shelby County's EPA zone, it outranks 68% of them by population. EPA's geology-based Region 5 groups Shelby County with 523 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

Shelby County's predicted average sits above EPA's own action level of 4 pCi/L — the concentration at which EPA recommends fixing a home — versus a national average around 1.3 pCi/L indoors and 0.4 pCi/L outdoors. Being in Zone 1 raises the odds Shelby 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 Shelby County

Mitigation cost doesn't depend on Shelby County's zone — it depends on the house's foundation. A typical system runs $800–$2,500 (about $1,200 typical), and testing first is what tells you whether that's needed at all.

Find Indiana's state radon program

Shelby County's test kit answers today; a Airthings radon monitor keeps answering for Shelby County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. Code RADONZONE-10OFF takes 10% off at checkout.

More on how this number was built

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.