What EPA's radon map says about Somerset County
EPA places Somerset 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. Somerset County sits at the 90th percentile nationally for radon potential — above 90 of every 100 rated counties.
Somerset County by the numbers
About 51,338 people live in Somerset County, Maine, spread over 3,924.289 square miles. That works out to roughly 13 people per square mile. Among counties sharing Somerset County's EPA zone, it outranks 71% of them by population. Geologically, Somerset County is grouped into EPA Region 1 alongside 58 other counties that share its rock and soil setting.
What this actually means for a house in Somerset County
Where the national indoor average runs about 1.3 pCi/L, Somerset 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 Somerset County will test well under the action level, and EPA's guidance is to test regardless of zone.
Testing and mitigation in Somerset County
Mitigation cost doesn't depend on Somerset County's zone — it depends on the house's foundation. A typical system runs $800–$2,500 (about $1,200 typical), and testing first is what tells you whether that's needed at all.
Find Maine's state radon program
Somerset County's test kit answers today; a Airthings radon monitor keeps answering for Somerset County over time. Affiliate link, RadonZoneCheck earns a commission there, at no extra cost to you. Code RADONZONE-10OFF takes 10% off at checkout.
More on how this number was built
Somerset County's zone, rank and region all trace back to named EPA and Census sources — the methodology guide lists exactly which ones. If you're unsure why a low zone still deserves a test, the zone explainer covers that directly.