What EPA's radon map says about Adams County

Adams County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Nationally, Adams County ranks higher in radon potential than 69% of rated counties (the 69th percentile).

Where Adams County sits nationally

About 3,606 people live in Adams County, Iowa, spread over 423.433 square miles. Averaged across its land area, Adams County runs about 9 people per square mile. Among counties sharing Adams County's EPA zone, it outranks 9% of them by population. EPA's geology-based Region 7 groups Adams County with 411 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

Fixing a home becomes an EPA recommendation past 4 pCi/L, and that is precisely the side of the line Adams County's Zone 1 prediction lands on, well above the roughly 1.3 pCi/L most US homes average. Being in Zone 1 raises the odds Adams County homes test above the action level, but it does not mean any specific house does — EPA recommends every home be tested, in every zone, because the only way to know is to test.

Testing and mitigation in Adams County

Mitigation cost doesn't depend on Adams 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

Adams County's test kit answers today; a Airthings radon monitor keeps answering for Adams 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

Adams 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.