Radon levels in Connecticut

Verified county-level radon indicators are available for 8 Connecticut counties. Select a county for its source period and sample details.

High results are most common in Windham County (34%) and least common in Hartford County (21%)Share of tests at or above 4 pCi/L by county · Radon test results from laboratories, 2008–2017 · 8 of 8 counties have data
Middlesex County: 31% of tests at or above 4 pCi/L · 1,600 testsNew Haven County: 26% of tests at or above 4 pCi/L · 5,084 testsWindham County: 34% of tests at or above 4 pCi/L · 1,340 testsNew London County: 28% of tests at or above 4 pCi/L · 2,081 testsFairfield County: 27% of tests at or above 4 pCi/L · 7,638 testsTolland County: 27% of tests at or above 4 pCi/L · 1,316 testsLitchfield County: 29% of tests at or above 4 pCi/L · 1,595 testsHartford County: 21% of tests at or above 4 pCi/L · 4,918 tests
  • Under 10%
  • 10–20%
  • 20–30%
  • 30–40%
  • 40% or more
  • No data

Counties

CountyTests% ≥ 4 pCi/LMedian (pCi/L)EPA zone (1993)Source
Fairfield County7,63827%2.1Zone 1Radon test results from laboratories through 2017
Hartford County4,91821%1.5Zone 3Radon test results from laboratories through 2017
Litchfield County1,59529%2.0Zone 2Radon test results from laboratories through 2017
Middlesex County1,60031%2.2Zone 1Radon test results from laboratories through 2017
New Haven County5,08426%1.8Zone 1Radon test results from laboratories through 2017
New London County2,08128%2.1Zone 1Radon test results from laboratories through 2017
Tolland County1,31627%2.2Zone 2Radon test results from laboratories through 2017
Windham County1,34034%2.6Zone 2Radon test results from laboratories through 2017

Test your home

County figures show how often tests come back high, not the level in your home. Only a test tells you that: see how to test for radon.

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