Randolph County, IN radon potential
EPA places Randolph 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. Nationally that's the 83rd percentile for radon potential — Randolph County outranks 83% of every county EPA has rated.
Where Randolph County sits nationally
Randolph County, Indiana is home to about 24,337 people across 452.379 square miles. That works out to roughly 54 people per square mile. Within its own EPA zone, Randolph County is bigger by population than 51% of the counties that share it. Randolph County falls in EPA Radon Region 5, one of 524 counties nationally EPA assigns to that same geologic province.
What this actually means for a house in Randolph County
Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Randolph County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. That doesn't mean every Randolph County house tests high — a zone is a county-wide prediction, never a single-home reading — but it's a reason to test sooner rather than let it wait.
Testing and mitigation in Randolph 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 Randolph County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Randolph County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.
Where Randolph County's figures come from
The methodology guide shows exactly which EPA and Census sources feed Randolph County's numbers. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.