What EPA's radon map says about Hardin County

Hardin County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Nationally, Hardin County ranks higher in radon potential than 80% of rated counties (the 80th percentile).

Hardin County by the numbers

About 16,464 people live in Hardin County, Iowa, spread over 569.307 square miles. Population density there runs about 29 people per square mile. Among counties sharing Hardin County's EPA zone, it outranks 41% of them by population. Hardin County falls in EPA Radon Region 7, one of 412 counties nationally EPA assigns to that same geologic province.

What this actually means for a house in Hardin County

Fixing a home becomes an EPA recommendation past 4 pCi/L, and that is precisely the side of the line Hardin County's Zone 1 prediction lands on, well above the roughly 1.3 pCi/L most US homes average. Some Hardin County homes will test comfortably under the action level despite the county's Zone 1 rating — the only way to know which kind of home you have is an actual test.

Testing and mitigation in Hardin County

Mitigation cost doesn't depend on Hardin 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 Iowa's state radon program

Hardin County's test kit answers today; a Airthings radon monitor keeps answering for Hardin County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

More on how this number was built

Hardin County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.