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

Aroostook County is mapped as Zone 1 - Highest Potential by EPA — meaning the county-wide average indoor level is predicted above 4 pCi/L. Rank it against the rest of the country and Aroostook County lands in the 92nd percentile for radon potential.

Aroostook County by the numbers

Aroostook County, Maine is home to about 66,776 people across 6,671.22 square miles. That works out to roughly 10 people per square mile. By population, Aroostook County is the 253rd largest of every county sharing its EPA zone — the 76th percentile by population within that zone. EPA's geology-based Region 1 groups Aroostook County with 58 other counties nationally sharing its underlying rock and soil profile.

Zone vs. an actual test

Where the national indoor average runs about 1.3 pCi/L, Aroostook County's Zone 1 rating puts its predicted county average above EPA's 4 pCi/L action level itself. A Zone 1 rating means testing is worth doing sooner rather than later, but it is still county-wide average, not a reading for any single house — some homes in Aroostook County will test well under the action level, and EPA's guidance is to test regardless of zone.

Testing and mitigation in Aroostook County

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

Where Aroostook County's figures come from

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