Elmore County, ID: EPA's radon zone, explained
Elmore 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 Elmore County lands in the 85th percentile for radon potential.
Where Elmore County sits nationally
Elmore County, Idaho is home to about 29,729 people across 3,075.079 square miles. Population density there runs about 10 people per square mile. By population, Elmore County is the 470th largest of every county sharing its EPA zone — the 56th percentile by population within that zone. Elmore County falls in EPA Radon Region 10, one of 142 counties nationally EPA assigns to that same geologic province.
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 Elmore 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 Elmore 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 Elmore County
For a Elmore 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 Idaho's state radon program
For Elmore County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Elmore County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. Code RADONZONE-10OFF takes 10% off at checkout.
Where Elmore County's figures come from
Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. Whatever zone Elmore County carries, the zone explainer covers what it does and doesn't tell you about any one house.