Is Idaho County, ID a radon risk area?

Idaho County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Rank it against the rest of the country and Idaho County lands in the 81st percentile for radon potential.

How Idaho County compares

About 17,912 people live in Idaho County, Idaho, spread over 8,477.499 square miles. Averaged across its land area, Idaho County runs about 2 people per square mile. Rank 602 by population within its EPA zone puts Idaho County at the 44th percentile among zone peers. Geologically, Idaho County is grouped into EPA Region 10 alongside 141 other counties that share its rock and soil setting.

Zone vs. an actual test

Idaho 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. Being in Zone 1 raises the odds Idaho 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.

If Idaho County tests above the action level

Nothing about Idaho County's EPA zone changes the mitigation number: $800–$2,500 nationally (around $1,200 typical), set by the house's foundation rather than the county it sits in — and only relevant once a test actually clears 4 pCi/L.

Find Idaho's state radon program

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

More on how this number was built

The methodology guide shows exactly which EPA and Census sources feed Idaho County's numbers. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.