Radon levels in Massachusetts

Verified county-level radon indicators are available for 14 Massachusetts counties. Select a county for its source period and sample details.

High results are most common in Worcester County (34%) and least common in Nantucket County (5%)Share of tests at or above 4 pCi/L by county · Radon test results from laboratories, 2008–2017 · 14 of 14 counties have data
Barnstable County: 21% of tests at or above 4 pCi/L · 6,521 testsBerkshire County: 27% of tests at or above 4 pCi/L · 1,097 testsBristol County: 23% of tests at or above 4 pCi/L · 13,358 testsDukes County: 17% of tests at or above 4 pCi/L · 317 testsEssex County: 29% of tests at or above 4 pCi/L · 20,398 testsFranklin County: 22% of tests at or above 4 pCi/L · 802 testsHampden County: 13% of tests at or above 4 pCi/L · 3,452 testsHampshire County: 19% of tests at or above 4 pCi/L · 2,457 testsMiddlesex County: 22% of tests at or above 4 pCi/L · 75,220 testsNantucket County: 5% of tests at or above 4 pCi/L · 40 testsNorfolk County: 21% of tests at or above 4 pCi/L · 39,205 testsPlymouth County: 17% of tests at or above 4 pCi/L · 16,320 testsSuffolk County: 10% of tests at or above 4 pCi/L · 8,525 testsWorcester County: 34% of tests at or above 4 pCi/L · 46,440 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
Barnstable County6,52121%2.0Zone 2Radon test results from laboratories through 2017
Berkshire County1,09727%1.7Zone 2Radon test results from laboratories through 2017
Bristol County13,35823%2.0Zone 2Radon test results from laboratories through 2017
Dukes County31717%1.7Zone 2Radon test results from laboratories through 2017
Essex County20,39829%2.2Zone 1Radon test results from laboratories through 2017
Franklin County80222%1.6Zone 2Radon test results from laboratories through 2017
Hampden County3,45213%1.3Zone 2Radon test results from laboratories through 2017
Hampshire County2,45719%1.5Zone 2Radon test results from laboratories through 2017
Middlesex County75,22022%1.9Zone 1Radon test results from laboratories through 2017
Nantucket County405%1.8Zone 2Radon test results from laboratories through 2017
Norfolk County39,20521%1.8Zone 2Radon test results from laboratories through 2017
Plymouth County16,32017%1.7Zone 2Radon test results from laboratories through 2017
Suffolk County8,52510%1.3Zone 3Radon test results from laboratories through 2017
Worcester County46,44034%2.6Zone 1Radon 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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