Does radon mitigation work?

Yes. Properly installed systems typically reduce radon levels significantly. Post-mitigation testing confirms performance.

Radon Levels, Testing and Mitigation in Connecticut

Q: 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.

Q: How much does radon mitigation cost in Connecticut?

Radon mitigation typically costs between $800 and $2,500 depending on foundation type and severity.

Connecticut has 8 counties, with 4 classified as EPA Zone 1 (highest risk). With an average radon level of 6.87 pCi/L, Connecticut state testing data reveals significantly elevated risks across multiple counties. Testing is highly recommended.

Connecticut is the third least expansive in terms of size, and the 29th most populous. Of course, it also happens to be the fourth most densely populated state in the country.

6.87

Avg. pCi/L

Counties

Zone 1 Counties

Connecticut Radon Map

Zone 1 — High

Zone 2 — Moderate

Zone 3 — Low

Most Active Radon Markets in Connecticut

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

City	Avg User Radon Level	Submissions
Hamden	4.75 pCi/L	4
West Hartford	4.25 pCi/L	4
Greenwich	7.67 pCi/L	3
Norwalk	7.00 pCi/L	1
Stamford	5.00 pCi/L	1
Middletown	4.00 pCi/L	1
Guilford	No submissions	0
Ridgefield	No submissions	0

Connecticut Counties by EPA Radon Zone

All 8 Connecticut 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 4 counties

Fairfield County Zone 1

Avg: 7.1 pCi/L

Middlesex County Zone 1

Avg: 5.8 pCi/L

New Haven County Zone 1

Avg: 6.5 pCi/L

New London County Zone 1

Avg: 7.8 pCi/L

Zone 2 — Moderate Risk

Predicted avg. indoor levels 2–4 pCi/L

Zone 2 3 counties

Litchfield County Zone 2

Avg: 8.3 pCi/L

Tolland County Zone 2

Avg: 4.5 pCi/L

Windham County Zone 2

Avg: 6.7 pCi/L

Zone 3 — Low Risk

Predicted avg. indoor levels < 2 pCi/L

Zone 3 1 counties

Hartford County Zone 3

Avg: 5.8 pCi/L

Connecticut Cities & Towns

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

Amston Andover Ansonia Ashford Avon Baltic Bantam Barkhamsted Beacon Falls Berlin Bethany Bethel Bethlehem Bloomfield Bolton Branford Bridgeport Bridgewater Bristol Broad Brook Brookfield Brooklyn Burlington Canaan Canterbury Canton Canton Center Centerbrook Chaplin Cheshire Chester Clinton Colchester Colebrook Collinsville Columbia Cornwall Bridge Cos Cob Coventry Cromwell Danbury Danielson Darien Dayville Deep River Derby Durham East Berlin East Canaan East Granby East Haddam East Hampton East Hartford East Hartland East Haven East Killingly East Lyme East Windsor Eastford Easton Ellington Enfield Essex Fairfield Falls Village Farmington Gales Ferry Gaylordsville Gilman Glastonbury Goshen Granby Greenwich Groton Guilford Haddam Hamden Hampton Hartford Harwinton Hebron Higganum Ivoryton Jewett City Kent Killingworth Lakeside Lakeville Lebanon Ledyard Litchfield Madison Manchester Mansfield Center Marlborough Meriden Middlebury Middlefield Middletown Milford Monroe Montville Moodus Moosup Morris Mystic Naugatuck New Britain New Canaan New Fairfield New Hartford New Haven New London New Milford New Preston Marble Dale Newington Newtown Niantic Norfolk North Branford North Canton North Franklin North Granby North Grosvenordale North Haven North Stonington North Windham Northfield Northford Norwalk Norwich Oakdale Oakville Old Greenwich Old Lyme Old Saybrook Orange Oxford Pawcatuck Plainfield Plainville Plantsville Plymouth Pomfret Center Portland Preston Prospect Putnam Quaker Hill Quinebaug Redding Ridgefield Riverside Riverton Rockfall Rocky Hill Roxbury Salem Salisbury Sandy Hook Scotland Seymour Sharon Shelton Sherman Simsbury Somers South Glastonbury South Kent South Windham South Windsor Southbury Southington Southport Stafford Springs Stamford Sterling Stonington Storrs Mansfield Stratford Suffield Taftville Tariffville Terryville Thomaston Thompson Tolland Torrington Trumbull Uncasville Unionville Vernon Rockville Voluntown Wallingford Washington Washington Depot Waterbury Waterford Watertown Weatogue West Cornwall West Granby West Hartford West Hartland West Haven West Simsbury West Suffield Westbrook Weston Westport Wethersfield Willimantic Willington Wilton Windham Windsor Windsor Locks Winsted Wolcott Woodbridge Woodbury Woodstock Woodstock Valley

Frequently Asked Questions About Radon in Connecticut

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 Connecticut?

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 Connecticut county in?

Connecticut 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.