What EPA's radon map says about Audubon County

EPA places Audubon 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 Audubon County in the 71st percentile nationally for radon potential — higher than 71% of the counties EPA has rated.

Where Audubon County sits nationally

About 5,562 people live in Audubon County, Iowa, spread over 442.96 square miles. That works out to roughly 13 people per square mile. Among counties sharing Audubon County's EPA zone, it outranks 15% of them by population. Audubon 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 Audubon County

Audubon County's predicted average sits above EPA's own action level of 4 pCi/L — the concentration at which EPA recommends fixing a home — versus a national average around 1.3 pCi/L indoors and 0.4 pCi/L outdoors. Some Audubon 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.

If Audubon County tests above the action level

Mitigation cost doesn't depend on Audubon 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

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

More on how this number was built

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