Harmon County, OK: EPA's radon zone, explained

EPA's own radon map rates Harmon County zone 3 - low potential, predicting a county-wide average indoor level below 2 pCi/L. Rank it against the rest of the country and Harmon County lands in the 1st percentile for radon potential.

Harmon County by the numbers

Harmon County, Oklahoma is home to about 2,315 people across 537.258 square miles. Population density there runs about 4 people per square mile. By population, Harmon County is the 991st largest of every county sharing its EPA zone — the 4th percentile by population within that zone. Geologically, Harmon County is grouped into EPA Region 6 alongside 502 other counties that share its rock and soil setting.

Why the zone isn't the answer by itself

Well clear of both the 1.3 pCi/L national indoor average and EPA's 4 pCi/L action level, Harmon County's Zone 3 prediction is the low end of the scale. Don't read Zone 3 as a pass for Harmon County — EPA's guidance to test every home makes no exception for counties predicted low.

Next steps for a home in Harmon County

For a Harmon 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 Oklahoma's state radon program

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

Where Harmon 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.