Poweshiek County, IA: EPA's radon zone, explained

EPA places Poweshiek 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. That puts Poweshiek County in the 81st percentile nationally for radon potential — higher than 81% of the counties EPA has rated.

Where Poweshiek County sits nationally

Poweshiek County, Iowa is home to about 18,454 people across 584.932 square miles. Population density there runs about 32 people per square mile. By population, Poweshiek County is the 593rd largest of every county sharing its EPA zone — the 44th percentile by population within that zone. Poweshiek County falls in EPA Radon Region 7, one of 412 counties nationally EPA assigns to that same geologic province.

Why the zone isn't the answer by itself

Poweshiek County carries a Zone 1 label because its predicted average clears 4 pCi/L outright — three-plus times the 0.4 pCi/L typical outdoors and above the 1.3 pCi/L most homes see. That doesn't mean every Poweshiek 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 Poweshiek County

For a Poweshiek 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 Iowa's state radon program

For Poweshiek County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Poweshiek 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 Poweshiek County's figures come from

The methodology guide shows exactly which EPA and Census sources feed Poweshiek County's numbers. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.