What EPA's radon map says about Putnam County

EPA's own radon map rates Putnam County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Nationally, Putnam County ranks higher in radon potential than 87% of rated counties (the 87th percentile).

Putnam County by the numbers

About 37,804 people live in Putnam County, Indiana, spread over 480.536 square miles. That works out to roughly 79 people per square mile. Among counties sharing Putnam County's EPA zone, it outranks 63% of them by population. EPA's geology-based Region 5 groups Putnam County with 523 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Putnam County

Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Putnam County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. A Zone 1 rating means testing is worth doing sooner rather than later, but it is still county-wide average, not a reading for any single house — some homes in Putnam County will test well under the action level, and EPA's guidance is to test regardless of zone.

Testing and mitigation in Putnam County

Mitigation cost doesn't depend on Putnam 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

Putnam County's test kit answers today; a Airthings radon monitor keeps answering for Putnam 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

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