Franklin County, ME Radon Zone Data

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

EPA places Franklin County in Zone 1 - Highest Potential — a predicted county-wide average indoor radon level above 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 Franklin County lands in the 85th percentile for radon potential.

How Franklin County compares

Franklin County, Maine is home to about 30,902 people across 1,697.007 square miles. Averaged across its land area, Franklin County runs about 18 people per square mile. By population, Franklin County is the 458th largest of every county sharing its EPA zone — the 57th percentile by population within that zone. Franklin County falls in EPA Radon Region 1, one of 59 counties nationally EPA assigns to that same geologic province.

Zone vs. an actual test

Outdoor air nationally averages about 0.4 pCi/L, indoor air about 1.3 pCi/L — Franklin County's Zone 1 prediction clears both of those and EPA's fix-it threshold besides. That doesn't mean every Franklin 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 Franklin County

For a Franklin 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 Franklin County, an ongoing number beats a one-time test - a Airthings radon monitor tracks Franklin 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 Franklin County's figures come from

The methodology guide shows exactly which EPA and Census sources feed Franklin County's numbers. Whatever zone Franklin County carries, the zone explainer covers what it does and doesn't tell you about any one house.