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

Fremont County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. That puts Fremont County in the 72nd percentile nationally for radon potential — higher than 72% of the counties EPA has rated.

How Fremont County compares

Fremont County, Iowa is home to about 6,494 people across 511.168 square miles. That works out to roughly 13 people per square mile. By population, Fremont County is the 867th largest of every county sharing its EPA zone — the 19th percentile by population within that zone. EPA's geology-based Region 7 groups Fremont County with 411 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

Fremont 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. EPA's guidance doesn't change because of a Zone 1 label: test the house. What changes is the reason to not put it off in Fremont County specifically.

If Fremont County tests above the action level

For a Fremont 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 Fremont County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Fremont County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

Where Fremont County's figures come from

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