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Connecticut Radon Map and Levels by County

Connecticut's counties span all three EPA radon zones. Homes with elevated levels occur in all three zones, so only a test measures yours.

Data checked By Radon411Methodology

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  • Share at 4+ pCi/L

    26.7%

    9.1 pts below U.S.

    Connecticut
    26.7%
    U.S.
    35.8%

    25,634 tests across 8 counties, 2007 to 2016

  • Rank among states

    25 of 47

    Middle of the states

    Connecticut
    26.7%
    North Dakota
    58.7%

    By share, every state pooled the same way, 2007 to 2016

  • Counties in EPA Zone 1

    4 of 8

    Most at highest potential

    Zone 1
    4
    Zone 2
    3

    Most counties sit in Zone 1; Zone 1 is the highest potential

  • Highest county

    34.1%

    Windham County

    Windham
    34.1%
    Hartford
    21.1%

    Counties with 30+ tests, 2007 to 2016

Read a result for Connecticut

Starts at EPA's action level

4.0pCi/L

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

EPA’s reading of 4.0 pCi/L

At or above 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 at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. 26.7% of Connecticut's reported tests reached 4 pCi/L, 2007 to 2016.

Interpret this readingWhat a fix costs

The data

Connecticut, At a glance

Connecticut at a glance

Predicted: EPA radon zone

8 of 8 counties classified

EPA classifies counties, not states. Of the 8 counties in Connecticut with a zone, 4 are in Zone 1, 3 in Zone 2 and 1 in Zone 3.

  • Zone 1: Highest predicted potentialgreater than 4 pCi/L4 of 8 counties · 50.0%
  • Zone 2: Moderate predicted potential2 to 4 pCi/L3 of 8 counties · 37.5%
  • Zone 3: Lower predicted potentialless than 2 pCi/L1 of 8 counties · 12.5%

An EPA radon zone predicts a whole county. It is not intended to determine whether any individual home should be tested: homes with elevated levels occur in all three zones, and EPA recommends testing every home regardless of zone.

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

CDC test figures, county by county

CDC publishes Connecticut's radon test figures by county: 8 of its 8 counties have one. Each one's share is in the county list.

How to read these figures

Connecticut, Compared

Connecticut radon figures, compared

Calculated by Radon411
Connecticut, 2007 to 2016, laboratory
26.7%
of 25,634 tests at or above 4 pCi/L, pooled
Against the U.S.
−9.1points
35.8% pooled
Rank among the states
25 of 47
1 is the highest share
Counties with 30 or more tests
8
Highest
34.1%
Windham County
Lowest
21.1%
Hartford County

About 3 in 10 of the 25,634 tests reported for Connecticut over the 2007 to 2016 laboratory totals came back at or above 4 pCi/L (26.7%, 8 counties pooled). That is 25th of 47 states with county figures for the period; Michigan (26.8%) above it and Oregon (26.3%) below.

By band, 2 counties at 30% to 50%, 6 counties at 15% to 30%. Its 8 counties with 30 or more tests run from 21.1% in Hartford County to 34.1% in Windham County; in 0 of them half or more of the reported tests reached 4 pCi/L.

EPA's 1993 map puts 4 of its 8 classified counties in Zone 1; against that, 26.7% of the tests reported since reached 4 pCi/L. The national pool for the same period is 35.8%, so Connecticut runs 9.1 points below the country.

Across its 4 overlapping ten-year totals, the share went from 26.5% (2005 to 2014) to 26.5% (2008 to 2017), within 2 points, with 2006 to 2015 the highest at 26.8%.

Connecticut ranked among 47 states by pooled share of tests at or above 4 pCi/L, 2007 to 2016, laboratory
StateRankCountiesTestsAt or above 4 pCi/L
Tennessee20 of 479528,89833.4%
Missouri21 of 4711554,94630.8%
Virginia22 of 4713149,87230.6%
New Mexico23 of 47293,91530.0%
Michigan24 of 4783111,40626.8%
Connecticut25 of 47825,63426.7%
Oregon26 of 473422,26126.3%
Washington27 of 47387,88325.5%
New York28 of 476292,76124.9%
Maryland29 of 472444,23224.4%
Georgia30 of 4713729,45523.9%
Connecticut's highest counties with 30 or more tests, by share at or above 4 pCi/L, 2007 to 2016, laboratory
CountyRankTestsAt or above 4 pCi/L
Windham County1 of 81,30734.1%
Middlesex County2 of 81,60531.3%
Litchfield County3 of 81,60529.3%
New London County4 of 81,93528.3%
Fairfield County5 of 87,66827.6%
Tolland County6 of 81,39926.4%
New Haven County7 of 85,01626.1%
Hartford County8 of 85,09921.1%
Connecticut's counties with 30 or more tests, by their own share at or above 4 pCi/L, 2007 to 2016, laboratory
ShareCountiesTheir testsFor example
50% or more00None
30% to 50%22,912Windham County, Middlesex County
15% to 30%622,722Litchfield County, New London County, Fairfield County
5% to 15%00None
Under 5%00None
Connecticut ten-year laboratory totals, pooled, against the United States
PeriodCountiesTestsAt or above 4 pCi/LUnited StatesChange from the row before
2008 to 2017825,57226.5%35.7%−0.2 points
2007 to 2016825,63426.7%35.8%−0.1 points
2006 to 2015824,68426.8%36.3%+0.3 points
2005 to 2014823,28026.5%36.0%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period. CDC publishes no state or national figure.

Connecticut, Counties

Connecticut counties by EPA zone

Predicted

The map of Connecticut, then its 8 counties zone by zone, each with its reported share at or above 4 pCi/L and a report of its own.

Connecticut radon map by county: EPA radon zones. Map of Connecticut's 8 counties shaded by EPA radon zone: Zone 1 in red-orange, Zone 2 in amber, Zone 3 in pale sand. 4 in Zone 1, 3 in Zone 2, 1 in Zone 3.
Connecticut radon map by countyEPA radon zones for Connecticut's counties: 4 counties in Zone 1, 3 counties in Zone 2, 1 county in Zone 3.A prediction for each county, not a reading of any home; elevated homes occur in all three zones.

The 8 highest in Connecticut, 2007 to 2016

Local help

Connecticut, Local resources

Local resources in Connecticut

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

What Connecticut's program says
Phone
(860) 509-7300
Email
DPH.RadonReports@ct.gov
Licensing of radon professionals
The State of Connecticut does not license or otherwise certify radon professionals, however, the Radon Program maintains lists of nationally certified professionals in accordance with the requirements of CGS § 19a-14b (5)(b).

What it means

Connecticut, Questions

Questions about radon in Connecticut

Is radon a problem in Connecticut?

Connecticut has 8 counties on EPA's Map of Radon Zones: Zone 1, the highest predicted potential, for 4; Zone 2 for 3; Zone 3 for 1. Pooled from 8 counties, 26.7% of the 25,634 radon tests reported to CDC over the 2007 to 2016 laboratory totals were at or above 4 pCi/L, 25th of 47 states.

Who does radon mitigation in Connecticut?

71 radon businesses are listed for Connecticut, for testing, mitigation or both; each listing names the licensing list it was read from.

Which Connecticut counties are in EPA radon Zone 1?

Zone 1 holds 4 counties in Connecticut: Fairfield County, Middlesex County, New Haven County, New London County.

Which Connecticut counties have the highest radon?

Windham County 34.1% (1,307 tests) leads Connecticut by the share of reported tests at or above 4 pCi/L, 2007 to 2016, laboratory, then Middlesex County 31.3% (1,605 tests), Litchfield County 29.3% (1,605 tests), New London County 28.3% (1,935 tests), Fairfield County 27.6% (7,668 tests).

Which EPA region is Connecticut in?

Connecticut is in EPA Region 1: New England.

Products

Connecticut, Products

Testing a home in Connecticut

26.7% of the 25,634 tests reported to CDC for Connecticut over the 2007 to 2016 laboratory totals reached 4 pCi/L: a short-term kit (2 to 90 days) gives a first answer in days, a long-term test the year-round average. A short-term kit (2 to 90 days) is the quick first check for a home in Connecticut; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Connecticut homes, compared

Explore

Cities in Connecticut with their own page

Radon data is published by county, not by city. Each city page sets the figures of the counties the city lies in side by side.