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Radon Levels in Windham County, Vermont

EPA puts Windham County in Zone 2, its middle radon zone, and 21.7% of its 60 reported radon tests (2023) 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

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  • Share at 4+ pCi/L

    21.7%

    1.1 pts above VT

    Windham
    21.7%
    Vermont
    20.6%

    60 tests, 2023

  • Median result

    2.2pCi/L

    Below action level

    Windham
    2.2 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2023

  • Tests reported

    60

    8th of 12 by tests

    Windham
    60
    Chittenden
    398

    Reported to CDC before any fix, 2023

  • EPA radon zone

    Zone 2

    Moderate potential

    1. 1
    2. Zone 2
    3. 3

    1 highest, 3 lowest

    EPA predicts 2 to 4 pCi/L indoors

  • Rank in Vermont

    7 of 12

    Middle half

    Windham
    21.7%
    Bennington
    29.5%

    By share, of 12 with 30+ tests

Read a result for Windham County

Starts at Windham County's median, 2.2 pCi/L

2.2pCi/L

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

EPA’s reading of 2.2 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. Windham County's median reported result, 2023.

Interpret this readingWhat a fix costs

The data

Windham County, At a glance

Windham County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Windham County is a county: EPA's forecast for it as a whole is an average indoor of 2 to 4 pCi/L (75 to 150 Bq/m³). It describes no single address, and homes above EPA's are found in every zone, this one included.

USGS geologic potential: Moderate across 100% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Windham County, 2023

Share of reported tests at or above 4 pCi/L, by year, Windham County
Share of reported tests at or above 4 pCi/L, by year, Windham County
YearShare of reported tests at or above 4 pCi/L
201412.1%
20156.7%
20169.3%
201713.2%
201818.6%
20198.9%
202013.3%
202112.0%
202221.5%
202321.7%

2023: 21.7%. Across these years the share ran from 6.7% to 21.7%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 60 tests reported to CDC for Windham County over 2023, 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: 2023. Measured data period: 2005 to 2023 (every CDC figure on file).

How to read these figures

Windham County, Compared

Windham County radon figures, compared

Calculated by Radon411

Windham County's 60 reported tests in 2023 had a middle value of 2.2 pCi/L and a maximum of 8.0 pCi/L, and 21.7% reached 4 pCi/L. Vermont as a whole (14 Vermont counties, pooled) comes to 20.6%: 1.1 points lower than here.

Among its state's counties it ranks 7th of 12 Vermont counties with 30 or more tests for the same period. Statewide for the same period, Bennington County reported the highest share (29.5%) and Chittenden County the lowest (14.6%).

Below the action level, 29 tests (48.3%) came in under 2 pCi/L, against 56.8% statewide, and 18 tests (30.0%) fell between 2 and 4, against 22.5% statewide. The busiest year on file was 2022, with 279 tests reported; the quietest, 2015, had 45.

EPA's 1993 zone map puts Windham County in Zone 2, a predicted county average between 2 and 4 pCi/L. USGS geology rates 100% of the county's land moderate radon potential.

Next door, the shares run from 22.4% in Windsor County to 29.5% in Bennington County. Over 10 years of annual figures the share rose 9.6 points, from 12.1% in 2014 to 21.7% in 2023; its peak was 21.7% in 2023.

Share of reported tests at or above 4 pCi/L by year, Windham County against Vermont2014 to 2023, years with 30 or more tests: Windham County 12.1% to 21.7%, the state's pooled share 20.6% in 2023.
Windham CountyVermont, pooled
Share of reported tests at or above 4 pCi/L by year, Windham County against Vermont: data table
YearTestsWindham County, at or above 4 pCi/LVermont, pooled
20145812.1%18.3%
2015456.7%15.5%
2016549.3%15.9%
20179113.2%16.4%
20187018.6%15.8%
2019908.9%14.3%
20209013.3%16.5%
202111712.0%19.2%
202227921.5%19.4%
20236021.7%20.6%
Windham County against Vermont, the United States and nearby counties, 2023
AreaTestsAt or above 4 pCi/LMedianDifference from Windham County
Windham County6021.7%2.2 pCi/LThis county
Vermont, pooled14 counties, pooled1,30020.6%Not pooled−1.1 points
United States, pooled642 counties, pooled128,74033.4%Not pooled+11.7 points
Orange Countyhighest in the state5326.4%2.5 pCi/L+4.7 points
Chittenden Countylowest in the state39814.6%1.3 pCi/L−7.1 points
Bennington County, VTborders it4429.5%2.0 pCi/L+7.8 points
Windsor County, VTborders it6722.4%1.6 pCi/L+0.7 points
Where Windham County's reported results fell, 2023, beside Vermont and the United States
ResultWindham County testsWindham County shareVermont shareU.S. shareAgainst Vermont
Under 2 pCi/L2948.3%56.8%41.4%−8.5 points
2 to 4 pCi/L1830.0%22.5%25.2%+7.5 points
4 pCi/L and above1321.7%20.6%33.4%+1.1 points
Windham County ranked among the 12 Vermont counties with 30 or more tests, by share at or above 4 pCi/L, 2023
CountyRankTestsAt or above 4 pCi/LMedian
Orange County2 of 125326.4%2.5 pCi/L
Washington County3 of 1219926.1%2.0 pCi/L
Franklin County4 of 124723.4%1.5 pCi/L
Lamoille County5 of 126222.6%1.8 pCi/L
Windsor County6 of 126722.4%1.6 pCi/L
Windham County7 of 126021.7%2.2 pCi/L
Orleans County8 of 125121.6%1.7 pCi/L
Caledonia County9 of 127621.1%2.0 pCi/L
Addison County10 of 128319.3%1.7 pCi/L
Rutland County11 of 1213018.5%1.3 pCi/L
Chittenden County12 of 1239814.6%1.3 pCi/L
Windham County radon tests by year, against Vermont's pooled share
YearTestsAt or above 4 pCi/LMedianHighestVermont, pooledChange from the row before
20236021.7%2.2 pCi/L8.0 pCi/L20.6%+0.2 points
202227921.5%1.7 pCi/L50.7 pCi/L19.4%+9.5 points
202111712.0%1.5 pCi/L25.0 pCi/L19.2%−1.3 points
20209013.3%1.3 pCi/L15.8 pCi/L16.5%+4.4 points
2019908.9%1.3 pCi/L18.8 pCi/L14.3%−9.7 points
20187018.6%0.9 pCi/L12.8 pCi/L15.8%+5.4 points
20179113.2%1.2 pCi/L34.8 pCi/L16.4%+3.9 points
2016549.3%1.2 pCi/L21.2 pCi/L15.9%+2.6 points
2015456.7%1.3 pCi/L6.6 pCi/L15.5%−5.4 points
20145812.1%1.8 pCi/L12.6 pCi/L18.3%First on file

Pooled shares: Radon411's sum of CDC's county counts for one period.

Windham County, Geology

The ground under Windham County

Predicted

USGS's geologic map puts all of Windham County's mapped land in one class: moderate radon potential. The map puts 50.9% of Windham County in the area it calls Vermont Piedmont and 41.4% in Green Mountains, with one smaller area beside them. USGS gives both a radon index of 11, in the moderate band (9 to 11).

USGS's geologic areas under Windham County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Vermont PiedmontPaleozoic metavolcanic and metasedimentary rocks that are intruded by igneous plutonic rocks.Moderate1150.9%
Green MountainsProterozoic to Paleozoic metaigneous and metasedimentary rocks.Moderate1141.4%
Vermont PiedmontGranite and granitic gneiss of the New Hampshire plutonic series.Moderate117.5%

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

Windham County beside the ground around it

Windham County has more moderate-potential ground than Vermont as a whole: 100% of its land against 87.8%. Of the 5 counties that border it, 2 have more high-potential ground, Cheshire County, NH the most at 6.5%.

Share of land by USGS radon potential: Windham County, the 5 counties bordering it and Vermont
AreaEPA zoneLow potentialModerate potentialHigh potential
Windham CountyZone 2None100%None
Bennington CountyZone 2None100%None
Cheshire County, NHZone 27.3%86.2%6.5%
Franklin County, MAZone 214.5%85.5%None
Sullivan County, NHZone 210.7%88.2%1.1%
Windsor CountyZone 2None100%None
Vermont14 counties, pooled by land areaVaries12.2%87.8%None

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

Local help

Windham County, Local resources

Radon testing and mitigation in Windham County

What Vermont's program says
Phone
802-863-7220

What it means

Windham County, Questions

Questions about radon in Windham County

Are radon levels high in Windham County?

In 2023, 21.7% of the radon tests reported to CDC for Windham County, Vermont were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.2 pCi/L. Of 12 Vermont counties with 30 or more tests for the same period, 6 reported a higher share; pooled, the state comes to 20.6%.

Which counties border Windham County?

Windham County borders 5 counties: Bennington County, VT, Cheshire County, NH, Franklin County, MA, Sullivan County, NH and Windsor County, VT.

Products

Windham County, Products

Testing a home in Windham County

In Windham County, 21.7% of 60 tests reported to CDC in 2023 reached 4 pCi/L, against 20.6% pooled across Vermont. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Windham County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Windham County homes, compared

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Windham County, Bordering counties

Counties bordering Windham County

Calculated by Radon411

Windham County, Cities and towns

Cities and towns in Windham County

About 45,204 people live in Windham County by the Census Bureau's estimate for July 1, 2025, 654 fewer than in 2020 (−1.4%). That works out to 58 people per square mile of land. No town dominates: Bellows Falls, the largest, has 2,706 residents, 6.0% of the total. Together its 5 incorporated places hold 8.3% of those residents; the other 91.7% live outside any of them. Reported testing is thin here: 60 tests over 2023, or 1.3 for every 1,000 residents (2025 estimate), where Vermont as a whole comes to 2.0.

From Bellows Falls to Newfane, CDC publishes no figure by town: each reads Windham County's.

The cities and towns in Windham County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Bellows Falls2,706−3.1%6.0%
Saxtons River464−3.1%1.0%
Westminster277−1.8%0.6%
Jacksonville214−0.5%0.5%
Newfane92−1.1%0.2%

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).

Windham County, Homes

Homes in Windham County

Of Windham County's 30,104 homes, 68% are detached houses, against 67% across Vermont; 10% are in buildings of five or more homes. Half of its homes were built before 1974, close to Vermont's 1976: 35% date from before 1960 and 14% from 2000 or later. 73% of occupied homes are lived in by their owner (Vermont: 73%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Windham County, Vermont, 2019 to 2023
HomesWindham CountyVermont
Housing units30,104337,072
Detached houses68%67%
In buildings of 5 or more10%11%
Mobile homes4%6%
Built before 196035%33%
Built since 200014%17%
Middle year built19741976
Owner-occupied73%73%

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