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Radon Levels in Tolland County, Connecticut

EPA puts Tolland County in Zone 2, its middle radon zone, and 29.4% of its 221 reported radon tests (2019) 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

    29.4%

    5.7 pts below CT

    Tolland
    29.4%
    CT
    35.1%

    221 tests, 2019

  • Median result

    1.8pCi/L

    Below action level

    Tolland
    1.8 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2019

  • Tests reported

    221

    7th of 8 by tests

    Tolland
    221
    Fairfield
    2,784

    Reported to CDC before any fix, 2019

  • 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 CT

    8 of 8

    Lowest quarter

    Tolland
    29.4%
    New London
    48.5%

    By share, of 8 with 30+ tests

Read a result for Tolland County

Starts at Tolland County's median, 1.8 pCi/L

1.8pCi/L

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

EPA’s reading of 1.8 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. Tolland County's median reported result, 2019.

Interpret this reading

The data

Tolland County, At a glance

Tolland County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Tolland 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 66% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Tolland County, 2019

Share of reported tests at or above 4 pCi/L, by year, Tolland County
Share of reported tests at or above 4 pCi/L, by year, Tolland County
YearShare of reported tests at or above 4 pCi/L
201474.4%
201582.8%
201667.7%
201772.7%
201832.5%
201929.4%

2019: 29.4%. Across these years the share ran from 29.4% to 82.8%. Each column counts radon tests reported to CDC that year, not homes.

What these figures count

These are the 221 tests reported to CDC for Tolland County over 2019, 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: 2019. Measured data period: 2005 to 2019 (every CDC figure on file).

How to read these figures

Tolland County, Compared

Tolland County radon figures, compared

Calculated by Radon411

Tolland County's 221 reported tests in 2019 had a middle value of 1.8 pCi/L and a maximum of 91.0 pCi/L, and 29.4% reached 4 pCi/L. Connecticut as a whole (8 Connecticut counties, pooled) comes to 35.1%: 5.7 points higher than here.

Among its state's counties it ranks 8th of 8 Connecticut counties with 30 or more tests for the same period. Statewide for the same period, New London County reported the highest share (48.5%) and Hartford County the lowest (31.5%).

Below the action level, 122 tests (55.2%) came in under 2 pCi/L, against 47.9% statewide, and 34 tests (15.4%) fell between 2 and 4, against 17.0% statewide. The busiest year on file was 2019, with 221 tests reported; the quietest, 2014, had 86.

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

Next door, the shares run from 31.5% in Hartford County to 48.5% in New London County. Over 6 years of annual figures the share fell 45.0 points, from 74.4% in 2014 to 29.4% in 2019; its peak was 82.8% in 2015.

Share of reported tests at or above 4 pCi/L by year, Tolland County against Connecticut2014 to 2019, years with 30 or more tests: Tolland County 74.4% to 29.4%, the state's pooled share 35.1% in 2019.
Tolland CountyConnecticut, pooled
Share of reported tests at or above 4 pCi/L by year, Tolland County against Connecticut: data table
YearTestsTolland County, at or above 4 pCi/LConnecticut, pooled
20148674.4%53.1%
201514582.8%63.4%
201612467.7%45.1%
201712172.7%38.3%
201811432.5%31.0%
201922129.4%35.1%
Tolland County against Connecticut, the United States and nearby counties, 2019
AreaTestsAt or above 4 pCi/LMedianDifference from Tolland County
Tolland County22129.4%1.8 pCi/LThis county
Connecticut, pooled8 counties, pooled6,09135.1%Not pooled+5.7 points
United States, pooled828 counties, pooled391,41229.0%Not pooled−0.4 points
New Haven Countyhighest in the state1,00737.9%2.2 pCi/L+8.5 points
Fairfield Countylowest in the state2,78433.4%2.1 pCi/L+4.0 points
New London County, CTborders it39648.5%3.5 pCi/L+19.1 points
Windham County, CTborders it16039.4%2.1 pCi/L+10.0 points
Hartford County, CTborders it60631.5%1.4 pCi/L+2.1 points
Where Tolland County's reported results fell, 2019, beside Connecticut and the United States
ResultTolland County testsTolland County shareConnecticut shareU.S. shareAgainst Connecticut
Under 2 pCi/L12255.2%47.9%48.0%+7.3 points
2 to 4 pCi/L3415.4%17.0%23.0%−1.6 points
4 pCi/L and above6529.4%35.1%29.0%−5.7 points
Tolland County ranked among the 8 Connecticut counties with 30 or more tests, by share at or above 4 pCi/L, 2019
CountyRankTestsAt or above 4 pCi/LMedian
New London County1 of 839648.5%3.5 pCi/L
Windham County2 of 816039.4%2.1 pCi/L
New Haven County3 of 81,00737.9%2.2 pCi/L
Middlesex County4 of 857134.5%2.0 pCi/L
Litchfield County5 of 834633.8%2.0 pCi/L
Fairfield County6 of 82,78433.4%2.1 pCi/L
Hartford County7 of 860631.5%1.4 pCi/L
Tolland County8 of 822129.4%1.8 pCi/L
Tolland County radon tests by year, against Connecticut's pooled share
YearTestsAt or above 4 pCi/LMedianHighestConnecticut, pooledChange from the row before
201922129.4%1.8 pCi/L91.0 pCi/L35.1%−3.1 points
201811432.5%2.1 pCi/L16.5 pCi/L31.0%−40.2 points
201712172.7%5.5 pCi/L59.0 pCi/L38.3%+5.0 points
201612467.7%5.2 pCi/L37.1 pCi/L45.1%−15.1 points
201514582.8%6.0 pCi/L106.0 pCi/L63.4%+8.4 points
20148674.4%5.5 pCi/L40.0 pCi/L53.1%First on file

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

Tolland County, Geology

The ground under Tolland County

Predicted

USGS's geologic map splits Tolland County: 66.3% of its land is moderate radon potential and 27.8% high and 5.9% low. The map puts 66.3% of Tolland County in the area it calls Merrimack Synclinorium and 23.0% in Bronson Hill Anticlinorium, with 2 smaller areas beside them. USGS gives the first a radon index of 11, in the moderate band (9 to 11), and the second 12, in the high band (12 to 17).

USGS's geologic areas under Tolland County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Merrimack SynclinoriumSchist, gneiss, gabbro.Moderate1166.3%
Bronson Hill AnticlinoriumGranite gneiss, schist, amphibolite.High1223.0%
Newark Terrane (Mesozoic Basins)Sedimentary and igneous rocks including dolerite, arkose, basalt.Low85.9%
Avalonian TerraneMafic gneiss and granite.High124.7%

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

Tolland County beside the ground around it

Connecticut as a whole has more high-potential ground than Tolland County: 44.1% of its land, against 27.8% here. Of the 5 counties that border it, 2 have more high-potential ground, Worcester County, MA the most at 85.4%.

Share of land by USGS radon potential: Tolland County, the 5 counties bordering it and Connecticut
AreaEPA zoneLow potentialModerate potentialHigh potential
Tolland CountyZone 25.9%66.3%27.8%
Windham CountyZone 2None81.2%18.8%
Hartford CountyZone 375.3%5.0%19.6%
New London CountyZone 1None39.9%58.4%
Hampden County, MAZone 241.7%47.6%10.7%
Worcester County, MAZone 1None14.6%85.4%
Connecticut8 counties, pooled by land areaVaries18.2%37.2%44.1%

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

Local help

Tolland County, Local resources

Radon testing and mitigation in Tolland County

What Connecticut's program says
Phone
(860) 509-7300
Email
DPH.RadonReports@ct.gov
Licensing of radon professionals
The State of Connecticut does not license or otherwise certify radon professionals, however, the Radon Program maintains lists of nationally certified professionals in accordance with the requirements of CGS § 19a-14b (5)(b).

What it means

Tolland County, Questions

Questions about radon in Tolland County

Are radon levels high in Tolland County?

In 2019, 29.4% of the radon tests reported to CDC for Tolland County, Connecticut were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.8 pCi/L. Of 8 Connecticut counties with 30 or more tests for the same period, 7 reported a higher share; pooled, the state comes to 35.1%.

Which counties border Tolland County?

Tolland County borders 5 counties: Windham County, CT, Hartford County, CT, New London County, CT, Hampden County, MA and Worcester County, MA.

Products

Tolland County, Products

Testing a home in Tolland County

In Tolland County, 29.4% of 221 tests reported to CDC in 2019 reached 4 pCi/L, against 35.1% pooled across Connecticut. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Tolland County; a long-term test tells the year-round average.

Test kits and monitors3

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Best radon monitors for Tolland County homes, compared

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Tolland County, Bordering counties

Counties bordering Tolland County

Calculated by Radon411