Indiana Radon Risk by County
The EPA divides Indiana counties into radon zones based on predicted average indoor radon levels. Zone 1 counties have the highest risk — roughly 1 in 3 homes tests above the EPA action level of 4 pCi/L.
0
Zone 1 — High Risk
>4 pCi/L avg
0
Zone 2 — Moderate
2–4 pCi/L avg
0
Zone 3 — Low
<2 pCi/L avg
Important: EPA zone levels are predicted averages based on geology. Individual homes can test high even in Zone 2 or Zone 3 counties. The only way to know your home's radon level is to test it. The EPA recommends testing all homes regardless of zone.
Source: EPA Map of Radon Zones
County zones are determined by the EPA's Map of Radon Zones, based on indoor radon measurements, geology, aerial radioactivity, soil parameters, and foundation type. See EPA Radon Zone documentation.