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Radon Levels, Testing and Mitigation in Maine

Maine has 16 counties, with 12 classified as EPA Zone 1 (highest risk). With an average radon level of 8.15 pCi/L, Maine state testing data reveals significantly elevated risks across multiple counties. Testing is highly recommended.

Maine is the 39th most expansive in terms of size, and the 41st most populous.

Maine does have an active radon program, dedicated to educating citizens about the risks associated with the deadly gas. You can find more information on Radon, testing and mitigation at the official page.

8.15
Avg. pCi/L
16
Counties
12
Zone 1 Counties

Maine Radon Map

Maine radon levels by county
Zone 1 — High
Zone 2 — Moderate
Zone 3 — Low

Maine Metro Areas

Explore radon data organized by metro region, including average levels, hotspot cities, and local mitigation professionals.

Bangor Metro
5 cities
Portland Metro
5 cities

Most Active Radon Markets in Maine

Cities with the most user-submitted radon test data, ranked by number of submissions.

CityAvg User Radon LevelSubmissions
Rumford 5.67 pCi/L 3
York 8.50 pCi/L 2
Saco 7.50 pCi/L 2
Hampden 4.50 pCi/L 2
Scarborough 14.00 pCi/L 1
Kittery 12.00 pCi/L 1
South Portland 10.00 pCi/L 1
Portland 4.00 pCi/L 1

Maine Counties by EPA Radon Zone

All 16 Maine counties with their EPA radon zone classification and user-submitted average radon levels.

Zone 1 — High Risk
Predicted avg. indoor levels > 4.0 pCi/L
Zone 1 12 counties
Androscoggin County Zone 1
Avg: 4.3 pCi/L
Aroostook County Zone 1
Avg: 10.6 pCi/L
Cumberland County Zone 1
Avg: 12.4 pCi/L
Franklin County Zone 1
Avg: 5.0 pCi/L
Hancock County Zone 1
Avg: 10.2 pCi/L
Kennebec County Zone 1
Avg: 5.0 pCi/L
Lincoln County Zone 1
Avg: 6.6 pCi/L
Oxford County Zone 1
Avg: 5.8 pCi/L
Penobscot County Zone 1
Avg: 9.4 pCi/L
Piscataquis County Zone 1
Avg:
Somerset County Zone 1
Avg:
York County Zone 1
Avg: 8.4 pCi/L
Zone 2 — Moderate Risk
Predicted avg. indoor levels 2–4 pCi/L
Zone 2 4 counties
Knox County Zone 2
Avg:
Sagadahoc County Zone 2
Avg: 3.0 pCi/L
Waldo County Zone 2
Avg: 5.0 pCi/L
Washington County Zone 2
Avg: 12.0 pCi/L

Maine Cities & Towns

Browse radon data for individual cities across Maine. Each city page includes user-submitted radon levels, local contractors, and mitigation resources.

Abbot Acton Addison Albion Alfred Alna Andover Anson Ashland Athens Auburn Augusta Aurora Bailey Island Baileyville Bangor Bar Harbor Bass Harbor Bath Belfast Belgrade Belgrade Lakes Benedicta Bernard Berwick Bethel Biddeford Bingham Birch Harbor Blue Hill Boothbay Boothbay Harbor Bowdoin Bowdoinham Bradford Bradley Bremen Brewer Bridgewater Bridgton Bristol Brooklin Brooks Brooksville Brookton Brownfield Brownville Brunswick Bryant Pond Buckfield Bucksport Burlington Burnham Bustins Island Buxton Calais Cambridge Camden Canaan Canton Cape Elizabeth Cape Neddick Caratunk Caribou Carmel Casco Castine Chamberlain Charleston Chebeague Island Cherryfield Clayton Lake Clinton Columbia Falls Corea Corinna Corinth Cornish Cumberland Center Cumberland Foreside Cushing Cutler Damariscotta Danforth Deer Isle Denmark Dennysville Detroit Dexter Dixfield Dixmont Dover Foxcroft Dresden Dryden Durham Eagle Lake East Andover East Baldwin East Boothbay East Livermore East Machias East Millinocket East Waterboro Easton Eastport Eddington Edgecomb Eliot Ellsworth Etna Eustis Exeter Fairfield Falmouth Farmingdale Farmington Fort Fairfield Fort Kent Frankfort Franklin Freedom Freeport Frenchville Friendship Fryeburg Gardiner Garland Georgetown Gorham Gouldsboro Grand Isle Gray Greenbush Greene Greenville Greenville Junction Greenwood Guilford Hallowell Hampden Hancock Hanover Harborside Harmony Harpswell Harrington Harrison Hartland Hebron Hiram Holden Hollis Center Hope Houlton Howland Hudson Island Falls Isle Of Springs Islesboro Jackman Jay Jefferson Jonesboro Jonesport Kenduskeag Kennebunk Kennebunkport Kents Hill Kingfield Kingman Kittery Kittery Point Lagrange Lebanon Lee Leeds Levant Lewiston Liberty Limerick Limestone Limington Lincoln Lincolnville Lisbon Lisbon Falls Litchfield Little Deer Isle Livermore Livermore Falls Long Island Lovell Lubec Machias Machiasport Madawaska Madison Manchester Mapleton Mars Hill Mattawamkeag Mechanic Falls Meddybemps Medway Mexico Milbridge Milford Millinocket Milo Minot Monmouth Monroe Monson Monticello Morrill Mount Desert Mount Vernon Naples New Gloucester New Harbor New Portland New Sharon New Sweden New Vineyard Newcastle Newport Newry Nobleboro Norridgewock North Anson North Berwick North Haven North Monmouth North Vassalboro North Waterboro North Yarmouth Norway Oakfield Oakland Ogunquit Old Orchard Beach Old Town Orient Orland Orono Orrington Orrs Island Owls Head Oxbow Oxford Palermo Palmyra Parsonsfield Passadumkeag Patten Peaks Island Pemaquid Pembroke Penobscot Perham Perry Peru Phillips Phippsburg Pittsfield Plymouth Poland Portage Porter Portland Pownal Presque Isle Princeton Prospect Harbor Randolph Rangeley Raymond Readfield Richmond Robbinston Rockland Rockport Rockwood Round Pond Roxbury Rumford Sabattus Saco Saint Agatha Saint Albans Saint David Saint Francis Sanford Sangerville Sargentville Scarborough Seal Cove Searsmont Searsport Sebago Sebago Lake Sedgwick Shapleigh Sherman Sinclair Skowhegan Smithfield Smyrna Mills Solon Sorrento South Berwick South Bristol South China South Paris South Portland South Thomaston Southport Southwest Harbor Springfield Springvale Spruce Head Stacyville Standish Steep Falls Stetson Steuben Stockholm Stockton Springs Stoneham Stonington Stratton Strong Sullivan Sumner Sunset Surry Swans Island Temple Tenants Harbor Thomaston Thorndike Topsfield Topsham Trevett Troy Turner Union Unity Van Buren Vassalboro Vienna Vinalhaven Waite Waldoboro Wallagrass Walpole Warren Washburn Washington Waterboro Waterford Waterville Wayne Weld Wells Wesley West Baldwin West Enfield West Forks West Newfield West Paris Westbrook Westfield Whitefield Whiting Wilton Windham Windsor Winn Winter Harbor Winterport Winthrop Wiscasset Woolwich Wytopitlock Yarmouth York

Frequently Asked Questions About Radon in Maine

What radon level is considered "high"?
The EPA action level is 4.0 pCi/L — many homeowners also choose to fix levels between 2.0 and 4.0 pCi/L. Any home with levels at or above 4.0 pCi/L should be mitigated.
How much does radon mitigation cost in Maine?
Radon mitigation typically costs between $800 and $2,500, depending on foundation type and radon severity. A standard sub-slab depressurization system usually falls in the $1,000–$1,500 range.
Does mitigation actually work?
Yes — properly installed systems typically reduce radon levels by up to 99%. A post-mitigation test confirms the system is working correctly, and many homeowners re-test periodically.
Should I test again after mitigation?
Yes. A post-mitigation test is the proof your system is working. The EPA recommends testing within 30 days of installation and retesting every two years.
What EPA Radon Zone is my Maine county in?
Maine counties are classified into three EPA Radon Zones. Zone 1 (highest risk, >4 pCi/L) indicates the most concern. Zone 2 (moderate, 2–4 pCi/L) and Zone 3 (lowest, <2 pCi/L) round out the classification. Use the county directory above to find your specific county's zone and data.

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