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Radon Levels, Testing and Mitigation in Massachusetts

Massachusetts has 14 counties, with 3 classified as EPA Zone 1 (highest risk). With an average radon level of 7.57 pCi/L, Massachusetts state testing data reveals significantly elevated risks across multiple counties. Testing is highly recommended.

Massachusetts is the 7th smallest state and the 14th most populous. It also happens to be the third most densely populated state in the entire US. Massachusetts 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.

7.57
Avg. pCi/L
14
Counties
3
Zone 1 Counties

Massachusetts Radon Map

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

Massachusetts Metro Areas

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

Northampton Metro
5 cities
Cape Cod Metro
5 cities
Boston Metro
5 cities
Providence Metro
5 cities
Springfield Metro
5 cities
Worcester Metro
5 cities

Most Active Radon Markets in Massachusetts

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

CityAvg User Radon LevelSubmissions
Littleton 9.40 pCi/L 5
Gloucester 8.40 pCi/L 5
Florence 7.40 pCi/L 5
Douglas 12.00 pCi/L 4
Weymouth 8.50 pCi/L 4
Mashpee 5.00 pCi/L 4
Natick 5.00 pCi/L 4
Worcester 17.67 pCi/L 3
Attleboro 10.00 pCi/L 3
Stoneham 9.67 pCi/L 3
Hopkinton 9.33 pCi/L 3
Medford 8.00 pCi/L 3
Boxford 6.67 pCi/L 3
Reading 5.67 pCi/L 3
Haverhill 5.00 pCi/L 3
Melrose 5.00 pCi/L 3
Somerville 4.33 pCi/L 3
Woburn 19.00 pCi/L 2
Marlborough 13.50 pCi/L 2
Cohasset 11.50 pCi/L 2

Massachusetts Counties by EPA Radon Zone

All 14 Massachusetts 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 3 counties
Essex County Zone 1
Avg: 6.6 pCi/L
Middlesex County Zone 1
Avg: 7.3 pCi/L
Worcester County Zone 1
Avg: 9.1 pCi/L
Zone 2 — Moderate Risk
Predicted avg. indoor levels 2–4 pCi/L
Zone 2 10 counties
Barnstable County Zone 2
Avg: 6.2 pCi/L
Berkshire County Zone 2
Avg: 8.2 pCi/L
Bristol County Zone 2
Avg: 7.5 pCi/L
Dukes County Zone 2
Avg:
Franklin County Zone 2
Avg: 9.1 pCi/L
Hampden County Zone 2
Avg: 7.1 pCi/L
Hampshire County Zone 2
Avg: 7.0 pCi/L
Nantucket County Zone 2
Avg:
Norfolk County Zone 2
Avg: 8.0 pCi/L
Plymouth County Zone 2
Avg: 7.5 pCi/L
Zone 3 — Low Risk
Predicted avg. indoor levels < 2 pCi/L
Zone 3 1 counties
Suffolk County Zone 3
Avg: 6.0 pCi/L

Massachusetts Cities & Towns

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

Abington Acton Acushnet Adams Agawam Allston Amesbury Amherst Andover Arlington Ashburnham Ashby Ashfield Ashland Ashley Falls Assonet Athol Attleboro Attleboro Falls Auburn Auburndale Avon Ayer Baldwinville Barnstable Barre Becket Bedford Belchertown Bellingham Belmont Berkley Berkshire Berlin Bernardston Beverly Billerica Blackstone Blandford Bolton Boston Boxborough Boxford Boylston Braintree Brewster Bridgewater Brighton Brimfield Brockton Brookfield Brookline Buckland Burlington Buzzards Bay Byfield Cambridge Canton Carlisle Carver Centerville Charlemont Charlestown Charlton Chatham Chelmsford Chelsea Cherry Valley Cheshire Chester Chesterfield Chestnut Hill Chicopee Chilmark Clinton Cohasset Colrain Concord Conway Cotuit Cummington Dalton Danvers Dedham Deerfield Dennis Dennis Port Devens Dighton Dorchester Dorchester Center Douglas Dover Dracut Drury Dudley Dunstable Duxbury East Bridgewater East Brookfield East Falmouth East Freetown East Longmeadow East Mansfield East Sandwich East Taunton East Walpole East Wareham East Weymouth Eastham Easthampton Edgartown Erving Essex Everett Fairhaven Fall River Falmouth Fayville Feeding Hills Fiskdale Fitchburg Florence Forestdale Foxboro Framingham Franklin Gardner Georgetown Gilbertville Gill Gloucester Goshen Grafton Granby Granville Great Barrington Greenfield Groton Groveland Hadley Halifax Hampden Hanover Hanscom Afb Hanson Harvard Harwich Harwich Port Hatfield Haverhill Haydenville Heath Hingham Hinsdale Holbrook Holden Holland Holliston Holyoke Hopedale Hopkinton Housatonic Hubbardston Hudson Hull Huntington Hyannis Hyde Park Indian Orchard Ipswich Jamaica Plain Jefferson Kingston Lakeville Lancaster Lanesboro Lawrence Lee Leeds Leicester Lenox Leominster Leverett Lexington Lincoln Littleton Longmeadow Lowell Ludlow Lunenburg Lynn Lynnfield Malden Manchester Mansfield Marblehead Marion Marlborough Marshfield Marstons Mills Mashpee Mattapan Mattapoisett Maynard Medfield Medford Medway Melrose Mendon Merrimac Methuen Middleboro Middleton Milford Millbury Millers Falls Millis Millville Milton Monson Montague Monterey Nahant Nantucket Natick Needham Needham Heights New Bedford New Braintree New Salem Newbury Newburyport Newton Newton Center Newton Highlands Newton Lower Falls Newton Upper Falls Newtonville Norfolk North Adams North Andover North Attleboro North Billerica North Brookfield North Chatham North Chelmsford North Dartmouth North Dighton North Easton North Falmouth North Grafton North Oxford North Reading North Weymouth Northampton Northborough Northbridge Northfield Norton Norwell Norwood Oak Bluffs Oakham Orange Orleans Osterville Otis Oxford Palmer Paxton Peabody Pembroke Pepperell Petersham Pittsfield Plainfield Plainville Plymouth Plympton Pocasset Princeton Provincetown Quincy Randolph Raynham Reading Rehoboth Revere Richmond Rochdale Rochester Rockland Rockport Roslindale Rowe Rowley Roxbury Roxbury Crossing Royalston Russell Rutland Sagamore Beach Salem Salisbury Sandisfield Sandwich Saugus Savoy Scituate Seekonk Sharon Sheffield Shelburne Falls Sherborn Shirley Shrewsbury Shutesbury Somerset Somerville South Chatham South Dartmouth South Deerfield South Dennis South Easton South Egremont South Grafton South Hadley South Hamilton South Walpole South Weymouth South Yarmouth Southampton Southborough Southbridge Southfield Southwick Spencer Springfield Sterling Stockbridge Stoneham Stoughton Stow Sturbridge Sudbury Sunderland Sutton Swampscott Swansea Taunton Templeton Tewksbury Three Rivers Topsfield Townsend Turners Falls Tyngsboro Upton Uxbridge Village Of Nagog Woods Vineyard Haven Waban Wakefield Wales Walpole Waltham Ware Wareham Warwick Watertown Wayland Webster Wellesley Wellesley Hills Wellfleet Wendell Wendell Depot Wenham West Barnstable West Boylston West Bridgewater West Brookfield West Chesterfield West Dennis West Harwich West Hatfield West Newbury West Newton West Roxbury West Springfield West Stockbridge West Townsend West Wareham West Yarmouth Westborough Westfield Westford Westminster Weston Westport Westwood Weymouth Whitinsville Whitman Wilbraham Williamsburg Williamstown Wilmington Winchendon Winchester Windsor Winthrop Woburn Woods Hole Worcester Worthington Wrentham Yarmouth Port

Frequently Asked Questions About Radon in Massachusetts

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 Massachusetts?
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 Massachusetts county in?
Massachusetts 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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