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

EPA places Jerome County in Zone 2 - Moderate Potential — a predicted county-wide average indoor radon level between 2 and 4 pCi/L, based on the geology, soil and aerial radioactivity data behind EPA's national map. Rank it against the rest of the country and Jerome County lands in the 49th percentile for radon potential.

How Jerome County compares

Jerome County, Idaho is home to about 26,056 people across 597.545 square miles. Population density there runs about 44 people per square mile. By population, Jerome County is the 538th largest of every county sharing its EPA zone — the 48th percentile by population within that zone. EPA's geology-based Region 10 groups Jerome County with 141 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in Jerome County

Call it a middle case: above the 1.3 pCi/L most US homes average, below the 4 pCi/L line EPA uses to recommend mitigation — that's Jerome County's Zone 2 prediction. Jerome County's Zone 2 rating sits in the middle nationally; EPA's guidance is unchanged by that — test every home regardless of its zone.

Testing and mitigation in Jerome County

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

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