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Radon Levels in Addison County, Vermont

EPA puts Addison County in Zone 2, its middle radon zone, and 19.3% of its 83 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

    19.3%

    1.3 pts below VT

    Addison
    19.3%
    Vermont
    20.6%

    83 tests, 2023

  • Median result

    1.7pCi/L

    Below action level

    Addison
    1.7 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2023

  • Tests reported

    83

    4th of 12 by tests

    Addison
    83
    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

    10 of 12

    Lowest quarter

    Addison
    19.3%
    Bennington
    29.5%

    By share, of 12 with 30+ tests

Read a result for Addison County

Starts at Addison County's median, 1.7 pCi/L

1.7pCi/L

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

EPA’s reading of 1.7 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. Addison County's median reported result, 2023.

Interpret this reading

The data

Addison County, At a glance

Addison County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Addison 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: Low across 66% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Addison County, 2023

Share of reported tests at or above 4 pCi/L, by year, Addison County
Share of reported tests at or above 4 pCi/L, by year, Addison County
YearShare of reported tests at or above 4 pCi/L
201415.9%
201515.4%
201618.2%
201715.5%
201811.7%
201917.3%
202012.6%
202124.2%
202215.5%
202319.3%

2023: 19.3%. Across these years the share ran from 11.7% to 24.2%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 83 tests reported to CDC for Addison 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

Addison County, Compared

Addison County radon figures, compared

Calculated by Radon411

Addison County's 83 reported tests in 2023 had a middle value of 1.7 pCi/L and a maximum of 28.3 pCi/L, and 19.3% reached 4 pCi/L. Vermont as a whole (14 Vermont counties, pooled) comes to 20.6%: 1.3 points higher than here.

Among its state's counties it ranks 10th 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, 48 tests (57.8%) came in under 2 pCi/L, against 56.8% statewide, and 19 tests (22.9%) fell between 2 and 4, against 22.5% statewide. The busiest year on file was 2022, with 348 tests reported; the quietest, 2015, had 52.

EPA's 1993 zone map puts Addison County in Zone 2, a predicted county average between 2 and 4 pCi/L. USGS geology rates 66% of the county's land low radon potential.

Next door, the shares run from 14.6% in Chittenden County to 26.4% in Orange County, with Rutland County and Chittenden County below Addison County. Over 10 years of annual figures the share rose 3.4 points, from 15.9% in 2014 to 19.3% in 2023; its peak was 24.2% in 2021.

CDC also counts 10 tests taken after mitigation in Addison 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, Addison County against Vermont2014 to 2023, years with 30 or more tests: Addison County 15.9% to 19.3%, the state's pooled share 20.6% in 2023.
Addison CountyVermont, pooled
Share of reported tests at or above 4 pCi/L by year, Addison County against Vermont: data table
YearTestsAddison County, at or above 4 pCi/LVermont, pooled
20146315.9%18.3%
20155215.4%15.5%
201611018.2%15.9%
201716115.5%16.4%
201811111.7%15.8%
201913917.3%14.3%
202019012.6%16.5%
202116124.2%19.2%
202234815.5%19.4%
20238319.3%20.6%
Addison County against Vermont, the United States and nearby counties, 2023
AreaTestsAt or above 4 pCi/LMedianDifference from Addison County
Addison County8319.3%1.7 pCi/LThis county
Vermont, pooled14 counties, pooled1,30020.6%Not pooled+1.3 points
United States, pooled642 counties, pooled128,74033.4%Not pooled+14.1 points
Bennington Countyhighest in the state4429.5%2.0 pCi/L+10.2 points
Caledonia Countylowest in the state7621.1%2.0 pCi/L+1.8 points
Washington County, NYborders it250.0%10.6 pCi/L+30.7 points
Orange County, VTborders it5326.4%2.5 pCi/L+7.1 points
Washington County, VTborders it19926.1%2.0 pCi/L+6.8 points
Windsor County, VTborders it6722.4%1.6 pCi/L+3.1 points
Rutland County, VTborders it13018.5%1.3 pCi/L−0.8 points
Chittenden County, VTborders it39814.6%1.3 pCi/L−4.7 points
Essex County, NYborders it20.0%3.3 pCi/L−19.3 points
Where Addison County's reported results fell, 2023, beside Vermont and the United States
ResultAddison County testsAddison County shareVermont shareU.S. shareAgainst Vermont
Under 2 pCi/L4857.8%56.8%41.4%+1.0 points
2 to 4 pCi/L1922.9%22.5%25.2%+0.4 points
4 pCi/L and above1619.3%20.6%33.4%−1.3 points
Addison 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
Addison County radon tests by year, against Vermont's pooled share
YearTestsAt or above 4 pCi/LMedianHighestVermont, pooledChange from the row before
20238319.3%1.7 pCi/L28.3 pCi/L20.6%+3.8 points
202234815.5%1.5 pCi/L22.4 pCi/L19.4%−8.7 points
202116124.2%1.8 pCi/L23.9 pCi/L19.2%+11.6 points
202019012.6%1.3 pCi/L19.5 pCi/L16.5%−4.7 points
201913917.3%1.1 pCi/L29.3 pCi/L14.3%+5.6 points
201811111.7%1.2 pCi/L12.6 pCi/L15.8%−3.8 points
201716115.5%1.1 pCi/L13.4 pCi/L16.4%−2.7 points
201611018.2%1.3 pCi/L19.9 pCi/L15.9%+2.8 points
20155215.4%1.2 pCi/L17.1 pCi/L15.5%−0.5 points
20146315.9%1.4 pCi/L60.1 pCi/L18.3%First on file

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

Addison County, Geology

The ground under Addison County

Predicted

USGS's geologic map splits Addison County: 65.8% of its land is low radon potential and 34.2% moderate. The map puts 65.8% of Addison County in the area it calls Champlain Lowland and 32.7% in Green Mountains, with one smaller area beside them. USGS gives the first a radon index of 8, in the low band (5 to 8), and the second 11, in the moderate band (9 to 11).

USGS's geologic areas under Addison County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Champlain LowlandCambrian-Ordovician sedimentary rocks with little or low-grade metamorphism.Low865.8%
Green MountainsProterozoic to Paleozoic metaigneous and metasedimentary rocks.Moderate1132.7%
Vermont PiedmontPaleozoic metavolcanic and metasedimentary rocks that are intruded by igneous plutonic rocks.Moderate111.3%

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

Addison County beside the ground around it

Vermont as a whole has more moderate-potential ground than Addison County: 87.8% of its land, against 34.2% here. Of the 7 counties that border it, 1 has more high-potential ground, Washington County, NY the most at 53.7%.

Share of land by USGS radon potential: Addison County, the 7 counties bordering it and Vermont
AreaEPA zoneLow potentialModerate potentialHigh potential
Addison CountyZone 265.8%34.2%None
Washington CountyZone 2None100%None
Chittenden CountyZone 344.3%55.7%None
Rutland CountyZone 210.4%89.6%None
Orange CountyZone 2None100%None
Essex County, NYZone 391.6%8.4%None
Windsor CountyZone 2None100%None
Washington County, NYZone 120.9%25.4%53.7%
Vermont14 counties, pooled by land areaVaries12.2%87.8%None

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

Local help

Addison County, Local resources

Radon testing and mitigation in Addison County

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

What it means

Addison County, Questions

Questions about radon in Addison County

Are radon levels high in Addison County?

In 2023, 19.3% of the radon tests reported to CDC for Addison County, Vermont were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.7 pCi/L. Of 12 Vermont counties with 30 or more tests for the same period, 9 reported a higher share; pooled, the state comes to 20.6%.

Which counties border Addison County?

Addison County borders 7 counties: Washington County, VT, Chittenden County, VT, Rutland County, VT, Orange County, VT, Essex County, NY, Windsor County, VT and Washington County, NY.

Products

Addison County, Products

Testing a home in Addison County

In Addison County, 19.3% of 83 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 Addison County; a long-term test tells the year-round average.

Test kits and monitors3

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Best radon monitors for Addison County homes, compared

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Addison County, Bordering counties

Counties bordering Addison County

Calculated by Radon411

Addison County, Cities and towns

Cities and towns in Addison County

The Census Bureau estimates 38,048 residents in Addison County for July 1, 2025, 686 more than in 2020 (+1.8%). That works out to 50 people per square mile of land. Vergennes, its one incorporated place, has 2,559 residents, 6.7% of the total. CDC's 83 reported tests for 2023 work out to 2.2 per 1,000 residents (2025 estimate), close to Vermont's 2.0.

Vergennes is the one incorporated place here; CDC publishes no figure by town, so it reads Addison County's.

Vergennes, Addison County: residents on July 1, 2025
PlaceResidentsSince 2020Share of residents
Vergennes2,559+0.4%6.7%

One incorporated place, 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).

Addison County, Homes

Homes in Addison County

Addison County is a place of houses on their own lots: 77% of its 17,521 homes are detached single-family houses, against 67% across Vermont. Half of its homes were built before 1977, close to Vermont's 1976: 33% date from before 1960 and 18% from 2000 or later. Owners live in 80% of the occupied homes (Vermont: 73%), so for most households a test and a fix are their own to order.

Homes in Addison County, Vermont, 2019 to 2023
HomesAddison CountyVermont
Housing units17,521337,072
Detached houses77%67%
In buildings of 5 or more6%11%
Mobile homes7%6%
Built before 196033%33%
Built since 200018%17%
Middle year built19771976
Owner-occupied80%73%

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