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Radon Levels in Chittenden County, Vermont

EPA puts Chittenden County in Zone 3, its lowest radon zone, and most reported tests there come back low, though 14.6% of 398 (2023) reached 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

    14.6%

    6.0 pts below VT

    Chittenden
    14.6%
    Vermont
    20.6%

    398 tests, 2023

  • Median result

    1.3pCi/L

    Below action level

    Chittenden
    1.3 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2023

  • Tests reported

    398

    Most tested in Vermont

    Chittenden
    398

    Reported to CDC before any fix, 2023

  • EPA radon zone

    Zone 3

    Lower potential

    1. 1
    2. 2
    3. Zone 3

    1 highest, 3 lowest

    EPA predicts under 2 pCi/L indoors

  • Rank in Vermont

    12 of 12

    Lowest quarter

    Chittenden
    14.6%
    Bennington
    29.5%

    By share, of 12 with 30+ tests

Read a result for Chittenden County

Starts at Chittenden County's median, 1.3 pCi/L

1.3pCi/L

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

EPA’s reading of 1.3 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. Chittenden County's median reported result, 2023.

Interpret this reading

The data

Chittenden County, At a glance

Chittenden County at a glance

Predicted: EPA radon zone

EPA Zone 3: lower predicted potential

is EPA's lowest class, and its forecast for Chittenden County as a whole is an average indoor of less than 2 pCi/L (less than 75 Bq/m³). A low zone clears no address in it: homes above EPA's turn up in all three zones.

USGS geologic potential: Moderate across 56% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Chittenden County, 2023

Share of reported tests at or above 4 pCi/L, by year, Chittenden County
Share of reported tests at or above 4 pCi/L, by year, Chittenden County
YearShare of reported tests at or above 4 pCi/L
201411.4%
20159.3%
201613.4%
201710.2%
20188.1%
20197.1%
202011.6%
202112.1%
202212.1%
202314.6%

2023: 14.6%. Across these years the share ran from 7.1% to 14.6%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 398 tests reported to CDC for Chittenden 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

Chittenden County, Compared

Chittenden County radon figures, compared

Calculated by Radon411

Chittenden County reports fewer high tests than Vermont overall. 14.6% of its 398 tests in 2023 were at or above 4 pCi/L. That is 6.0 points below the 20.6% pooled from 14 Vermont counties.

Ordered from highest share down, it comes 12th of 12 Vermont counties with 30 or more tests for the same period. Nationally, every county with a figure for the same period pools to 33.4%; Chittenden County sits 18.8 points below it.

Next door, the shares run from 19.3% in Addison County to 26.1% in Washington County. Zone 3 on EPA's map (predicted average under 2 pCi/L) and a 14.6% share point the same way here.

Half the tests came in under 1.3 pCi/L and half over it; the single highest reached 28.1 pCi/L. The rest split 64.3% under 2 pCi/L and 21.1% from 2 to 4 (Vermont: 56.8% and 22.5%). Year by year, 2014 opened at 11.4% and 2023 closed at 14.6% (up 3.2 points), with 2023 the high at 14.6%.

The busiest year on file was 2022, with 1,260 tests reported; the quietest, 2015, had 258.

Share of reported tests at or above 4 pCi/L by year, Chittenden County against Vermont2014 to 2023, years with 30 or more tests: Chittenden County 11.4% to 14.6%, the state's pooled share 20.6% in 2023.
Chittenden CountyVermont, pooled
Share of reported tests at or above 4 pCi/L by year, Chittenden County against Vermont: data table
YearTestsChittenden County, at or above 4 pCi/LVermont, pooled
201426411.4%18.3%
20152589.3%15.5%
201635913.4%15.9%
201760810.2%16.4%
20184428.1%15.8%
20195537.1%14.3%
202066411.6%16.5%
202164512.1%19.2%
20221,26012.1%19.4%
202339814.6%20.6%
Chittenden County against Vermont, the United States and nearby counties, 2023
AreaTestsAt or above 4 pCi/LMedianDifference from Chittenden County
Chittenden County39814.6%1.3 pCi/LThis county
Vermont, pooled14 counties, pooled1,30020.6%Not pooled+6.0 points
United States, pooled642 counties, pooled128,74033.4%Not pooled+18.8 points
Bennington Countyhighest in the state4429.5%2.0 pCi/L+14.9 points
Rutland Countylowest in the state13018.5%1.3 pCi/L+3.9 points
Grand Isle County, VTborders it2030.0%1.5 pCi/L+15.4 points
Washington County, VTborders it19926.1%2.0 pCi/L+11.5 points
Clinton County, NYborders it1225.0%1.8 pCi/L+10.4 points
Franklin County, VTborders it4723.4%1.5 pCi/L+8.8 points
Lamoille County, VTborders it6222.6%1.8 pCi/L+8.0 points
Addison County, VTborders it8319.3%1.7 pCi/L+4.7 points
Essex County, NYborders it20.0%3.3 pCi/L−14.6 points
Where Chittenden County's reported results fell, 2023, beside Vermont and the United States
ResultChittenden County testsChittenden County shareVermont shareU.S. shareAgainst Vermont
Under 2 pCi/L25664.3%56.8%41.4%+7.5 points
2 to 4 pCi/L8421.1%22.5%25.2%−1.4 points
4 pCi/L and above5814.6%20.6%33.4%−6.0 points
Chittenden 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
Chittenden County radon tests by year, against Vermont's pooled share
YearTestsAt or above 4 pCi/LMedianHighestVermont, pooledChange from the row before
202339814.6%1.3 pCi/L28.1 pCi/L20.6%+2.5 points
20221,26012.1%1.4 pCi/L48.1 pCi/L19.4%Level
202164512.1%1.4 pCi/L51.2 pCi/L19.2%+0.5 points
202066411.6%1.3 pCi/L30.8 pCi/L16.5%+4.5 points
20195537.1%1.1 pCi/L26.3 pCi/L14.3%−1.0 points
20184428.1%1.1 pCi/L18.5 pCi/L15.8%−2.1 points
201760810.2%1.2 pCi/L65.0 pCi/L16.4%−3.2 points
201635913.4%1.3 pCi/L48.9 pCi/L15.9%+4.1 points
20152589.3%1.2 pCi/L19.1 pCi/L15.5%−2.1 points
201426411.4%1.6 pCi/L21.6 pCi/L18.3%First on file

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

Chittenden County, Geology

The ground under Chittenden County

Predicted

USGS's geologic map splits Chittenden County: 55.7% of its land is moderate radon potential and 44.3% low. The map puts 55.7% of Chittenden County in the area it calls Green Mountains and 44.3% in Champlain Lowland. USGS gives the first a radon index of 11, in the moderate band (9 to 11), and the second 8, in the low band (5 to 8).

USGS's geologic areas under Chittenden County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Green MountainsProterozoic to Paleozoic metaigneous and metasedimentary rocks.Moderate1155.7%
Champlain LowlandCambrian-Ordovician sedimentary rocks with little or low-grade metamorphism.Low844.3%

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

Chittenden County beside the ground around it

Vermont as a whole has more moderate-potential ground than Chittenden County: 87.8% of its land, against 55.7% here. Of the 7 counties that border it, 4 have more moderate-potential ground, Lamoille County the most at 100%.

Share of land by USGS radon potential: Chittenden County, the 7 counties bordering it and Vermont
AreaEPA zoneLow potentialModerate potentialHigh potential
Chittenden CountyZone 344.3%55.7%None
Lamoille CountyZone 2None100%None
Washington CountyZone 2None100%None
Grand Isle CountyZone 399.9%0.1%None
Franklin CountyZone 231.7%68.1%None
Addison CountyZone 265.8%34.2%None
Clinton County, NYZone 235.0%64.9%None
Essex County, NYZone 391.6%8.4%None
Vermont14 counties, pooled by land areaVaries12.2%87.8%None

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

Local help

Chittenden County, Local resources

Radon testing and mitigation in Chittenden County

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

What it means

Chittenden County, Questions

Questions about radon in Chittenden County

Are radon levels high in Chittenden County?

In 2023, 14.6% of the radon tests reported to CDC for Chittenden County, Vermont were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.3 pCi/L. Of 12 Vermont counties with 30 or more tests for the same period, 11 reported a higher share; pooled, the state comes to 20.6%.

Which counties border Chittenden County?

Chittenden County borders 7 counties: Lamoille County, VT, Washington County, VT, Grand Isle County, VT, Franklin County, VT, Addison County, VT, Clinton County, NY and Essex County, NY.

Products

Chittenden County, Products

Testing a home in Chittenden County

In Chittenden County, 14.6% of 398 tests reported to CDC in 2023 reached 4 pCi/L, against 20.6% pooled across Vermont. Zone 3 is the lowest label, yet homes at or above 4 pCi/L occur in every zone: a short-term kit (2 to 90 days) is the quick first check in Chittenden County.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Chittenden County homes, compared

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Chittenden County, Bordering counties

Counties bordering Chittenden County

Calculated by Radon411

Chittenden County, Cities and towns

Cities and towns in Chittenden County

Chittenden County's population has barely moved since 2020: 169,115 residents on July 1, 2025 against 168,412 then, by the Census Bureau's estimates. That works out to 315 people per square mile of land. Its largest town, Burlington, has 44,019 residents, 26.0% of the total. Together its 4 incorporated places hold 50.0% of those residents; the other 50.0% live outside any of them. CDC's 398 reported tests for 2023 work out to 2.4 per 1,000 residents (2025 estimate), close to Vermont's 2.0.

From Burlington to Winooski, CDC publishes no figure by town: each reads Chittenden County's.

The cities and towns in Chittenden County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Burlington44,019−1.6%26.0%
South Burlington21,394+5.7%12.7%
Essex Junction10,921+3.2%6.5%
Winooski8,239+2.3%4.9%

4 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).

Chittenden County, Homes

Homes in Chittenden County

Fewer than six in ten of Chittenden County's 74,025 homes are detached houses (51%, against 67% across Vermont); the rest are attached, in shared buildings or mobile. Half of its homes were built before 1980, close to Vermont's 1976: 26% date from before 1960 and 21% from 2000 or later. 64% 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 Chittenden County, Vermont, 2019 to 2023
HomesChittenden CountyVermont
Housing units74,025337,072
Detached houses51%67%
In buildings of 5 or more22%11%
Mobile homes3%6%
Built before 196026%33%
Built since 200021%17%
Middle year built19801976
Owner-occupied64%73%

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