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

EPA's own radon map rates York County zone 1 - highest potential, predicting a county-wide average indoor level above 4 pCi/L. Rank it against the rest of the country and York County lands in the 97th percentile for radon potential.

York County by the numbers

York County, Maine is home to about 220,143 people across 991.194 square miles. That works out to roughly 222 people per square mile. By population, York County is the 91st largest of every county sharing its EPA zone — the 92nd percentile by population within that zone. EPA's geology-based Region 1 groups York County with 58 other counties nationally sharing its underlying rock and soil profile.

What this actually means for a house in York County

York County's predicted average sits above EPA's own action level of 4 pCi/L — the concentration at which EPA recommends fixing a home — versus a national average around 1.3 pCi/L indoors and 0.4 pCi/L outdoors. That doesn't mean every York County house tests high — a zone is a county-wide prediction, never a single-home reading — but it's a reason to test sooner rather than let it wait.

Testing and mitigation in York County

For a York 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 York County, an ongoing number beats a one-time test - a Airthings radon monitor tracks York 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 York 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.