Canyon County, ID: EPA's radon zone, explained

EPA's own radon map rates Canyon County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. That puts Canyon County in the 63rd percentile nationally for radon potential — higher than 63% of the counties EPA has rated.

Canyon County by the numbers

Canyon County, Idaho is home to about 266,892 people across 587.049 square miles. Averaged across its land area, Canyon County runs about 455 people per square mile. By population, Canyon County is the 89th largest of every county sharing its EPA zone — the 91st percentile by population within that zone. EPA's geology-based Region 10 groups Canyon County with 141 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

Canyon County's predicted average falls between EPA's 4 pCi/L action level and the national indoor average of about 1.3 pCi/L (outdoor air runs roughly 0.4 pCi/L). A Zone 2 rating is a moderate county-wide average, not a guarantee about any one house in Canyon County — testing is the only way to know an individual home's actual level.

Testing and mitigation in Canyon County

For a Canyon 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 Canyon County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Canyon County's levels over time. RadonZoneCheck earns a commission there, at no extra cost to you. RADONZONE-10OFF at checkout knocks 10% off.

Where Canyon County's figures come from

Canyon County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. Whatever zone Canyon County carries, the zone explainer covers what it does and doesn't tell you about any one house.