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Radon in Stamford, Connecticut

EPA puts Fairfield County, where Stamford is, in Zone 1, its highest radon zone, and 33.4% of its 2,784 reported radon tests (2019) were at or above 4 pCi/L. Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    33.4%

    1.7 pts below CT

    Fairfield
    33.4%
    CT
    35.1%

    Fairfield, 6th of 8 in CT, 2019

  • Median result

    2.1pCi/L

    Below action level

    Fairfield
    2.1 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of Fairfield's tests, 2019

  • Nearest county

    37.9%

    New Haven, 39 miles

    New Haven
    37.9%
    Fairfield
    33.4%

    1,007 tests, 2019

  • EPA radon zone

    Zone 1

    Highest potential

    1. Zone 1
    2. 2
    3. 3

    1 highest, 3 lowest

    Fairfield, where Stamford is

  • Tests reported

    2,784

    In Fairfield

    Fairfield
    2,784
    New Haven
    1,007

    Reported to CDC before any fix, 2019

Read a result for Stamford

Starts at Fairfield County's median, 2.1 pCi/L

2.1pCi/L

EPA’s own thresholds; the figures are the area’s, never this home’s.

EPA’s reading of 2.1 pCi/L

Between 2 and 4 pCi/L

  1. Under 20 to 1.9 pCi/L
  2. 2 to 4consider a fix
  3. 4 and aboveEPA says fix it

This result is between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Fairfield County's median reported result, 2019.

Interpret this readingWhat a fix costs

The data

Stamford, What is published

What is published for Stamford

Information:

Every figure for Stamford is a county's

Radon data is published by county, not by city, so for Stamford it is Fairfield County's: its EPA zone (Zone 1) and the 2,784 tests reported to CDC for 2019. Only a test tells you about one home.

Stamford covers 37.6 square miles of land, all of it in Fairfield County. About 139,535 people live there, 3,709 to the square mile.

Stamford, Counties

The county Stamford lies in

Measured

Fairfield County's EPA zone and the figures CDC publishes for it, 2019.

Fairfield CountyZone 1Highest predicted potential

33.4%
Reported tests at or above 4 pCi/L
2.1 pCi/L
Median reported result
2,784 tests
Tests reported to CDC
6
Annual years on file

Fairfield County ranks 6th of 8 Connecticut counties with 30 or more tests for that period, 1.7 points below the 35.1% pooled across Connecticut's counties, 4.4 points above the national pool of 29.0%.

The counties nearest Stamford with a CDC figure for 2019, measured from the middle of the city: New Haven County (39 miles, 37.9% of 1,007 tests), Litchfield County (50 miles, 33.8% of 346 tests) and Middlesex County (59 miles, 34.5% of 571 tests). Across the 7 nearest, the share at or above 4 pCi/L runs from 29.4% to 48.5%; the farthest of them, Windham County, is 96 miles away at 39.4%.

The directory lists 2 businesses with an address in Stamford, 2 for testing. Connecticut's other cities with a page of their own: Danbury.

The counties around Stamford

By distance from the middle of Stamford; counties with 30 or more tests.

Nearest counties to Stamford with 30 or more tests
CountyDistanceTestsAt or above 4 pCi/LMedian
New Haven County39 mi1,00737.9%2.2 pCi/L
Litchfield County50 mi34633.8%2.0 pCi/L
Middlesex County59 mi57134.5%2.0 pCi/L
Hartford County65 mi60631.5%1.4 pCi/L
New London County80 mi39648.5%3.5 pCi/L
Tolland County82 mi22129.4%1.8 pCi/L
Windham County96 mi16039.4%2.1 pCi/L

Predicted: EPA Map of Radon Zones, by county. Measured: CDC tracking data, by county, 2019.

Stamford, Geology

The ground under Stamford

Predicted

USGS's geologic map puts all of Stamford's mapped land in one class: high radon potential. 98.1% of it lies in the area the map calls Connecticut Valley Synclinorium, to which USGS gives a radon index of 12, in the high band (12 to 17).

USGS's geologic areas under Stamford
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Connecticut Valley SynclinoriumSchist, gneiss and phyllite.High1298.1%

Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.

Stamford beside its county and Connecticut

Stamford sits on more high-potential ground than Fairfield County as a whole: 98.1% of the city against 79.5% of the county. Stamford has more high-potential ground than Connecticut as a whole: 98.1% of its land against 44.1%.

Share of land by USGS radon potential: Stamford, the county it lies in and Connecticut
AreaEPA zoneLow potentialModerate potentialHigh potential
StamfordBy countyNoneNone98.1%
Fairfield CountyZone 1None19.2%79.5%
Connecticut8 counties, pooled by land areaVaries18.2%37.2%44.1%

The map rates the ground, not the air in any home.

Stamford, Homes

Homes in Stamford

Stamford has 57,958 homes, and many share a building: 43% are in buildings of five or more, 34% are detached houses, against 59% across Connecticut. Half of its homes were built before 1972, close to Connecticut's 1967: 34% date from before 1960 and 21% from 2000 or later. Most occupied homes here are rented: owners live in 48% (Connecticut: 66%). A tenant can run a test; a fix is the landlord's to make.

Homes in Stamford, Connecticut, 2019 to 2023
HomesStamfordConnecticut
Housing units57,9581,536,049
Detached houses34%59%
In buildings of 5 or more43%18%
Mobile homesunder 1%1%
Built before 196034%41%
Built since 200021%12%
Middle year built19721967
Owner-occupied48%66%

Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.

Local help

Stamford, Professionals

Radon professionals listed in Stamford

Businesses whose listed city is Stamford, from the state registries and listings in the Radon411 directory, with the same business and certification status the directory shows.

2 listings with Stamford as the city. See radon testing in Stamford, or all radon professionals in Connecticut.

Stamford, Local resources

Local resources for Stamford

Who to ask in Connecticut: its radon program, test kits and professionals.

The program's own words on licensing are on the Connecticut page.

What it means

Stamford, Questions

Questions about radon in Stamford

What radon zone is Stamford in?

Stamford has no zone of its own: it shares Fairfield County's, Zone 1, the map's highest class: a predicted county average above 4 pCi/L.

What are radon levels in Stamford?

A high result is no surprise around Stamford: 33.4% of 2,784 tests reported from Fairfield County for 2019 reached 4 pCi/L or more. The median reported result was 2.1 pCi/L.

Should I test my home in Stamford?

Yes. About 930 of the 2,784 tests reported from Fairfield County were at or above 4 pCi/L. That is about what Connecticut as a whole reports (35.1%), and ranks Fairfield County 6th of the 8 Connecticut counties with 30 or more tests. No map says which homes those are. How to test a home.

What ground is Stamford built on, as far as radon goes?

USGS's geologic map puts all of Stamford on one named area, "Connecticut Valley Synclinorium", rated high for radon potential, radon index 12.

Is radon higher in the counties around Stamford?

Some are and some are not. Against Fairfield County's 33.4%, 5 of the 7 nearest counties with a figure report more and 2 less, from Tolland County (29.4%, 82 miles off) to New London County (48.5%, 80 miles off).

Who tests for or fixes radon in Stamford?

Radon411's directory has 2 businesses with an address in Stamford, all listed for testing, none for mitigation. Every entry names the public list it was taken from. Radon professionals in Stamford.

The answers use the published figures of Fairfield County, the county Stamford lies in.

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