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Radon Levels in Windsor County, Vermont

EPA puts Windsor County in Zone 2, its middle radon zone, and 22.4% of its 67 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

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    22.4%

    1.8 pts above VT

    Windsor
    22.4%
    Vermont
    20.6%

    67 tests, 2023

  • Median result

    1.6pCi/L

    Below action level

    Windsor
    1.6 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2023

  • Tests reported

    67

    6th of 12 by tests

    Windsor
    67
    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

    6 of 12

    Middle half

    Windsor
    22.4%
    Bennington
    29.5%

    By share, of 12 with 30+ tests

Read a result for Windsor County

Starts at Windsor County's median, 1.6 pCi/L

1.6pCi/L

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

EPA’s reading of 1.6 pCi/L

Below 2 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 below 2 pCi/L, the level at which EPA says a fix should be considered. Windsor County's median reported result, 2023.

Interpret this reading

The data

Windsor County, At a glance

Windsor County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Windsor 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 Windsor County, 2023

Share of reported tests at or above 4 pCi/L, by year, Windsor County
Share of reported tests at or above 4 pCi/L, by year, Windsor County
YearShare of reported tests at or above 4 pCi/L
201414.1%
201514.9%
201612.8%
201721.4%
201816.1%
201919.0%
202018.6%
202118.3%
202224.0%
202322.4%

2023: 22.4%. Across these years the share ran from 12.8% to 24.0%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 67 tests reported to CDC for Windsor 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

Windsor County, Compared

Windsor County radon figures, compared

Calculated by Radon411

Windsor County's 67 reported tests in 2023 had a middle value of 1.6 pCi/L and a maximum of 15.2 pCi/L, and 22.4% reached 4 pCi/L. Vermont as a whole (14 Vermont counties, pooled) comes to 20.6%: 1.8 points lower than here.

Among its state's counties it ranks 6th 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, 37 tests (55.2%) came in under 2 pCi/L, against 56.8% statewide, and 15 tests (22.4%) fell between 2 and 4, against 22.5% statewide. The busiest year on file was 2022, with 300 tests reported; the quietest, 2018, had 62.

EPA's 1993 zone map puts Windsor 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 18.5% in Rutland County to 29.5% in Bennington County, with Windham County, Addison County and Rutland County below Windsor County. Over 10 years of annual figures the share rose 8.3 points, from 14.1% in 2014 to 22.4% in 2023; its peak was 24.0% in 2022.

CDC also counts 5 tests taken after mitigation in Windsor County for the same period: tests in homes where a fix was already in.

Share of reported tests at or above 4 pCi/L by year, Windsor County against Vermont2014 to 2023, years with 30 or more tests: Windsor County 14.1% to 22.4%, the state's pooled share 20.6% in 2023.
Windsor CountyVermont, pooled
Share of reported tests at or above 4 pCi/L by year, Windsor County against Vermont: data table
YearTestsWindsor County, at or above 4 pCi/LVermont, pooled
20146414.1%18.3%
20156714.9%15.5%
20167812.8%15.9%
201711221.4%16.4%
20186216.1%15.8%
201910019.0%14.3%
202015618.6%16.5%
202117518.3%19.2%
202230024.0%19.4%
20236722.4%20.6%
Windsor County against Vermont, the United States and nearby counties, 2023
AreaTestsAt or above 4 pCi/LMedianDifference from Windsor County
Windsor County6722.4%1.6 pCi/LThis county
Vermont, pooled14 counties, pooled1,30020.6%Not pooled−1.8 points
United States, pooled642 counties, pooled128,74033.4%Not pooled+11.0 points
Washington Countyhighest in the state19926.1%2.0 pCi/L+3.7 points
Chittenden Countylowest in the state39814.6%1.3 pCi/L−7.8 points
Bennington County, VTborders it4429.5%2.0 pCi/L+7.1 points
Orange County, VTborders it5326.4%2.5 pCi/L+4.0 points
Windham County, VTborders it6021.7%2.2 pCi/L−0.7 points
Addison County, VTborders it8319.3%1.7 pCi/L−3.1 points
Rutland County, VTborders it13018.5%1.3 pCi/L−3.9 points
Where Windsor County's reported results fell, 2023, beside Vermont and the United States
ResultWindsor County testsWindsor County shareVermont shareU.S. shareAgainst Vermont
Under 2 pCi/L3755.2%56.8%41.4%−1.6 points
2 to 4 pCi/L1522.4%22.5%25.2%−0.1 points
4 pCi/L and above1522.4%20.6%33.4%+1.8 points
Windsor 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
Bennington County1 of 124429.5%2.0 pCi/L
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
Windsor County radon tests by year, against Vermont's pooled share
YearTestsAt or above 4 pCi/LMedianHighestVermont, pooledChange from the row before
20236722.4%1.6 pCi/L15.2 pCi/L20.6%−1.6 points
202230024.0%2.5 pCi/L19.5 pCi/L19.4%+5.7 points
202117518.3%1.6 pCi/L32.9 pCi/L19.2%−0.3 points
202015618.6%2.0 pCi/L12.5 pCi/L16.5%−0.4 points
201910019.0%1.9 pCi/L40.5 pCi/L14.3%+2.9 points
20186216.1%1.1 pCi/L29.4 pCi/L15.8%−5.3 points
201711221.4%2.1 pCi/L17.1 pCi/L16.4%+8.6 points
20167812.8%1.3 pCi/L9.9 pCi/L15.9%−2.1 points
20156714.9%1.2 pCi/L9.7 pCi/L15.5%+0.8 points
20146414.1%2.2 pCi/L15.2 pCi/L18.3%First on file

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

Windsor County, Geology

The ground under Windsor County

Predicted

USGS's geologic map puts all of Windsor County's mapped land in one class: moderate radon potential. The map puts 66.4% of Windsor County in the area it calls Vermont Piedmont and 21.6% 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 Windsor County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Vermont PiedmontPaleozoic metavolcanic and metasedimentary rocks that are intruded by igneous plutonic rocks.Moderate1166.4%
Green MountainsProterozoic to Paleozoic metaigneous and metasedimentary rocks.Moderate1121.6%
Vermont PiedmontGranite and granitic gneiss of the New Hampshire plutonic series.Moderate1112.1%

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

Windsor County beside the ground around it

Windsor County has more moderate-potential ground than Vermont as a whole: 100% of its land against 87.8%. Of the 7 counties that border it, 2 have more high-potential ground, Grafton County, NH the most at 17.7%.

Share of land by USGS radon potential: Windsor County, the 7 counties bordering it and Vermont
AreaEPA zoneLow potentialModerate potentialHigh potential
Windsor CountyZone 2None100%None
Sullivan County, NHZone 210.7%88.2%1.1%
Rutland CountyZone 210.4%89.6%None
Orange CountyZone 2None100%None
Addison CountyZone 265.8%34.2%None
Windham CountyZone 2None100%None
Grafton County, NHZone 23.5%78.8%17.7%
Bennington 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

Windsor County, Local resources

Radon testing and mitigation in Windsor County

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

What it means

Windsor County, Questions

Questions about radon in Windsor County

Are radon levels high in Windsor County?

In 2023, 22.4% of the radon tests reported to CDC for Windsor County, Vermont were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.6 pCi/L. Of 12 Vermont counties with 30 or more tests for the same period, 5 reported a higher share; pooled, the state comes to 20.6%.

Which counties border Windsor County?

Windsor County borders 7 counties: Sullivan County, NH, Rutland County, VT, Orange County, VT, Addison County, VT, Windham County, VT, Grafton County, NH and Bennington County, VT.

Products

Windsor County, Products

Testing a home in Windsor County

In Windsor County, 22.4% of 67 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 Windsor County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Windsor County homes, compared

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Windsor County, Bordering counties

Counties bordering Windsor County

Calculated by Radon411

Windsor County, Cities and towns

Cities and towns in Windsor County

About 57,312 people live in Windsor County by the Census Bureau's estimate for July 1, 2025, 415 fewer than in 2020 (−0.7%). That works out to 59 people per square mile of land. No town dominates: Woodstock, the largest, has 903 residents, 1.6% of the total. Reported testing is thin here: 67 tests over 2023, or 1.2 for every 1,000 residents (2025 estimate), where Vermont as a whole comes to 2.0.

From Woodstock to Perkinsville, CDC publishes no figure by town: each reads Windsor County's.

The 2 largest cities and towns in Windsor County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Woodstock903−2.7%1.6%
Ludlow767−1.7%1.3%
  • Perkinsville

3 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).

Windsor County, Homes

Homes in Windsor County

Of Windsor County's 34,773 homes, 70% 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: 37% date from before 1960 and 13% from 2000 or later. 75% 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 Windsor County, Vermont, 2019 to 2023
HomesWindsor CountyVermont
Housing units34,773337,072
Detached houses70%67%
In buildings of 5 or more10%11%
Mobile homes6%6%
Built before 196037%33%
Built since 200013%17%
Middle year built19741976
Owner-occupied75%73%

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