What EPA's radon map says about Greenlee County

EPA places Greenlee 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. Nationally that's the 39th percentile for radon potential — Greenlee County outranks 39% of every county EPA has rated.

How Greenlee County compares

About 9,410 people live in Greenlee County, Arizona, spread over 1,842.838 square miles. That works out to roughly 5 people per square mile. Among counties sharing Greenlee County's EPA zone, it outranks 19% of them by population. EPA's geology-based Region 9 groups Greenlee County with 94 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

Greenlee County's Zone 2 prediction clears the 1.3 pCi/L national indoor average without reaching EPA's own 4 pCi/L point for recommending a fix. Greenlee County's Zone 2 rating sits in the middle nationally; EPA's guidance is unchanged by that — test every home regardless of its zone.

Next steps for a home in Greenlee County

Mitigation cost doesn't depend on Greenlee 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 Arizona's state radon program

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

More on how this number was built

Every figure on this page traces to EPA's own Map of Radon Zones and Census data, documented in the methodology guide. Whatever zone Greenlee County carries, the zone explainer covers what it does and doesn't tell you about any one house.