Waldo County, ME: EPA's radon zone, explained

EPA's own radon map rates Waldo County zone 2 - moderate potential, predicting a county-wide average indoor level between 2 and 4 pCi/L. That puts Waldo County in the 53rd percentile nationally for radon potential — higher than 53% of the counties EPA has rated.

Waldo County by the numbers

Waldo County, Maine is home to about 40,617 people across 730.227 square miles. That works out to roughly 56 people per square mile. By population, Waldo County is the 395th largest of every county sharing its EPA zone — the 62nd percentile by population within that zone. EPA's geology-based Region 1 groups Waldo County with 58 other counties nationally sharing its underlying rock and soil profile.

Why the zone isn't the answer by itself

Waldo 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). A Zone 2 rating is a moderate county-wide average, not a guarantee about any one house in Waldo County — testing is the only way to know an individual home's actual level.

Testing and mitigation in Waldo County

For a Waldo 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 Maine's state radon program

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

Where Waldo County's figures come from

Waldo County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. The guide to what a radon zone actually means covers why testing matters in every zone, not just Zone 1.