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

Louisa 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 Louisa County in the 76th percentile nationally for radon potential — higher than 76% of the counties EPA has rated.

Where Louisa County sits nationally

Louisa County, Iowa is home to about 10,630 people across 401.777 square miles. That works out to roughly 26 people per square mile. By population, Louisa County is the 748th largest of every county sharing its EPA zone — the 30th percentile by population within that zone. EPA's geology-based Region 7 groups Louisa County with 411 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

Fixing a home becomes an EPA recommendation past 4 pCi/L, and that is precisely the side of the line Louisa County's Zone 1 prediction lands on, well above the roughly 1.3 pCi/L most US homes average. Some Louisa 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.

Next steps for a home in Louisa County

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

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