Grant County, OR: EPA's radon zone, explained

EPA places Grant 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 Grant County lands in the 37th percentile for radon potential.

Grant County by the numbers

Grant County, Oregon is home to about 7,093 people across 4,527.792 square miles. Population density there runs about 2 people per square mile. By population, Grant County is the 900th largest of every county sharing its EPA zone — the 13th percentile by population within that zone. Grant County falls in EPA Radon Region 10, one of 142 counties nationally EPA assigns to that same geologic province.

What this actually means for a house in Grant 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 Grant County's Zone 2 prediction. Middle-of-the-pack doesn't mean risk-free for any one Grant County address — a moderate county average still leaves individual homes to test either side of it.

If Grant County tests above the action level

For a Grant 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 Oregon's state radon program

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

Where Grant County's figures come from

The methodology guide shows exactly which EPA and Census sources feed Grant County's numbers. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.