Graham County, AZ: EPA's radon zone, explained

EPA's own radon map rates Graham County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. Nationally that's the 53rd percentile for radon potential — Graham County outranks 53% of every county EPA has rated.

Graham County by the numbers

Graham County, Arizona is home to about 40,242 people across 4,621.877 square miles. That works out to roughly 9 people per square mile. By population, Graham County is the 398th largest of every county sharing its EPA zone — the 61st percentile by population within that zone. Geologically, Graham County is grouped into EPA Region 9 alongside 94 other counties that share its rock and soil setting.

Zone vs. an actual test

Graham 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). Nothing about a Zone 2 label lowers the case for testing in Graham County — EPA recommends it in every zone, moderate included.

If Graham County tests above the action level

For a Graham 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 Arizona's state radon program

For Graham County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Graham 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 Graham 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. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.