Short-term kit
RA400 short-term liquid scintillation radon test kit, lab fee included
- Lab fee included
Method: Liquid scintillation
In home: 48 to 96 hours
Locations and reports
Radon Levels in Bristol County, Massachusetts
EPA puts Bristol County in Zone 2, its middle radon zone, and 23.2% of its 13,358 reported radon tests (2008 to 2017, laboratory totals) 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
Share at 4+ pCi/L
23.2%
0.6 pts below MA
- Bristol
- 23.2%
- MA
- 23.8%
13,358 tests, 2008 to 2017
Median result
2.0pCi/L
Below action level
- Bristol
- 2.0 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
13,358
6th of 14 by tests
- Bristol
- 13,358
- Middlesex
- 75,220
Reported to CDC before any fix, 2008 to 2017
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
EPA predicts 2 to 4 pCi/L indoors
Rank in MA
4 of 14
Top quarter
- Bristol
- 23.2%
- Worcester
- 33.5%
By share, of 14 with 30+ tests
Read a result for Bristol County
Starts at Bristol County's median, 2.0 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 2.0 pCi/L
Between 2 and 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 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. Bristol County's median reported result, 2008 to 2017.
The data
Bristol County, At a glance
Bristol County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Bristol County is a
USGS geologic potential: Moderate across 96% of the county's area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Bristol County, 2008 to 2017, laboratory
Under 2 pCi/L: 49%2 to 4 pCi/L: 28%4 pCi/L and above: 23%
Of 13,358 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 6,534 | 48.9% |
| 2 to 4 pCi/L | 3,720 | 27.8% |
| 4 pCi/L and above | 3,104 | 23.2% |
What these figures count
These are the 13,358 tests reported to CDC for Bristol County over 2008 to 2017 (laboratory totals), many from homes being sold or already suspected of a problem: they describe the county's reported tests, not this house.
Measured: CDC tracking data. Figure above: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).
Bristol County, Compared
Bristol County radon figures, compared
Calculated by Radon411Bristol County's 13,358 reported tests over the 2008 to 2017 laboratory totals had a middle value of 2.0 pCi/L and a maximum of 100.0 pCi/L, and 23.2% reached 4 pCi/L. Massachusetts as a whole (14 Massachusetts counties, pooled) comes to 23.8%: 0.6 points higher than here.
Among its state's counties it ranks 4th of 14 Massachusetts counties with 30 or more tests for the same period. Statewide for the same period, Worcester County reported the highest share (33.5%) and Nantucket County the lowest (5.0%).
Below the action level, 6,534 tests (48.9%) came in under 2 pCi/L, against 49.6% statewide, and 3,720 tests (27.8%) fell between 2 and 4, against 26.6% statewide. CDC's ten-year totals for Bristol County went from 13,212 tests (2005 to 2014) to 13,358 (2008 to 2017), the share going from 22.8% to 23.2%.
EPA's 1993 zone map puts Bristol County in Zone 2, a predicted county average between 2 and 4 pCi/L. USGS geology rates 96% of the county's land moderate radon potential.
Next door, the shares run from 14.8% in Bristol County, RI to 24.4% in Newport County, RI, with Norfolk County, Plymouth County and Providence County, RI below Bristol County.
CDC also counts 77 tests taken after mitigation in Bristol County for the same period: tests in homes where a fix was already in.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Bristol County, Geology
The ground under Bristol County
PredictedMost of the ground under Bristol County is one class on USGS's geologic map: 96.2% of its land is moderate radon potential, with 0.1% low. The map puts 55.0% of Bristol County in the area it calls Narrangansett Basin and 41.1% in Esmond-Dedham terrane. USGS gives the first a radon index of 9 and the second 11, both in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Narrangansett Basin | Pennsylvanian sedimentary rocks. | Moderate | 9 | 55.0% |
| Esmond-Dedham terrane | Granite plutons, mafic metasedimentary and metavolcanic rocks. | Moderate | 11 | 41.1% |
Names, descriptions and indexes: U.S. Geological Survey, Geologic Radon Potential Map (2025). Shares: Radon411, from the map cut to the boundary.
Bristol County beside the ground around it
Across Massachusetts 31.9% of the land is rated high; none of Bristol County's is. Of the 5 counties that border it, 3 have more high-potential ground, Newport County, RI the most at 39.8%.
The map rates the ground, not the air in any home.
Local help
Bristol County, Local resources
Radon testing and mitigation in Bristol County
- Radon UnitRadon Unit, run by Department of Public Health, answers questions about testing, mitigation and the rules in Massachusetts.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsAsk the program whether it has free or discounted kits, or compare kits you can buy.
- Compare kits
- Professionals in Massachusetts5 professionals are listed in Massachusetts.
What Massachusetts's program says
- Phone
- (800) 723-6695
- DPHIAQ.radon@mass.gov
What it means
Bristol County, Questions
Questions about radon in Bristol County
Are radon levels high in Bristol County?
Over the 2008 to 2017 laboratory totals, 23.2% of the radon tests reported to CDC for Bristol County, Massachusetts were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.0 pCi/L. Of 14 Massachusetts counties with 30 or more tests for the same period, 3 reported a higher share; pooled, the state comes to 23.8%.
Which counties border Bristol County?
Bristol County borders 5 counties: Bristol County, RI, Newport County, RI, Plymouth County, MA, Providence County, RI and Norfolk County, MA.
Products
Bristol County, Products
Testing a home in Bristol County
In Bristol County, 23.2% of 13,358 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 23.8% pooled across Massachusetts. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Bristol County; a long-term test tells the year-round average.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL416 long-term radon test kit, lab fee included
- Lab fee included
Method: Alpha track
In home: 90 days to 12 months
Monitor
RadonPro Wi-Fi radon monitor with a built-in Geiger counter
- C-NRPP 2024/25: Not included
- Plug-in
- Wi-Fi
- Alarm
- Screen, app
First reading: Within 5 minutes
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Bristol County, Bordering counties
Counties bordering Bristol County
Calculated by Radon411- Radon levels in Newport County, RIEPA zone 2
24.4%at or above 4 pCi/L
Median 1.9 pCi/L · 2,792 tests · 1.2 points above Bristol County
- Radon levels in Norfolk County, MAEPA zone 2
21.2%at or above 4 pCi/L
Median 1.8 pCi/L · 39,205 tests · 2.0 points below Bristol County
- Radon levels in Plymouth County, MAEPA zone 2
17.0%at or above 4 pCi/L
Median 1.7 pCi/L · 16,320 tests · 6.2 points below Bristol County
- Radon levels in Providence County, RIEPA zone 2
16.8%at or above 4 pCi/L
Median 1.6 pCi/L · 17,655 tests · 6.4 points below Bristol County
- Radon levels in Bristol County, RIEPA zone 3
14.8%at or above 4 pCi/L
Median 1.6 pCi/L · 1,867 tests · 8.4 points below Bristol County
Bristol County, Cities and towns
Cities and towns in Bristol County
The Census Bureau estimates 593,640 residents in Bristol County for July 1, 2025, 16,917 more than in 2020 (+2.9%). Packed into its land, that is 1,073 people per square mile. No town dominates: New Bedford, the largest, has 101,834 residents, 17.2% of the total. Together its 5 incorporated places hold 57.0% of those residents; the other 43.0% live outside any of them. CDC's 13,358 reported tests for 2008 to 2017 work out to 22.5 per 1,000 residents (2025 estimate), close to Massachusetts' 32.7.
From New Bedford to North Attleborough Town, CDC publishes no figure by town: each reads Bristol County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| New Bedford | 101,834 | +0.9% | 17.2% |
| Fall River | 95,298 | +1.5% | 16.1% |
| Taunton | 62,522 | +5.2% | 10.5% |
| Attleboro | 47,447 | +2.1% | 8.0% |
| North Attleborough Town | 31,506 | +2.2% | 5.3% |
5 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. Residents: U.S. Census Bureau population estimates for July 1, 2025 (Vintage 2025).
Bristol County, Homes
Homes in Bristol County
Fewer than six in ten of Bristol County's 244,166 homes are detached houses (52%, against 51% across Massachusetts); the rest are attached, in shared buildings or mobile. Half of its homes were built before 1963, close to Massachusetts' 1963: 47% date from before 1960 and 11% from 2000 or later. 62% of occupied homes are lived in by their owner (Massachusetts: 63%); in the rest a tenant can run a test, but a fix is the landlord's to make.
| Homes | Bristol County | Massachusetts |
|---|---|---|
| Housing units | 244,166 | 3,014,657 |
| Detached houses | 52% | 51% |
| In buildings of 5 or more | 17% | 22% |
| Mobile homes | 1% | 1% |
| Built before 1960 | 47% | 47% |
| Built since 2000 | 11% | 14% |
| Middle year built | 1963 | 1963 |
| Owner-occupied | 62% | 63% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.