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Radon Levels in Kennebec County, Maine

EPA puts Kennebec County in Zone 1, its highest radon zone, and 30.3% of its 696 reported radon tests (2008 to 2017, laboratory totals) 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

    30.3%

    7.3 pts below ME

    Kennebec
    30.3%
    Maine
    37.6%

    696 tests, 2008 to 2017

  • Median result

    2.1pCi/L

    Below action level

    Kennebec
    2.1 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    696

    5th of 16 by tests

    Kennebec
    696
    Cumberland
    4,076

    Reported to CDC before any fix, 2008 to 2017

  • EPA radon zone

    Zone 1

    Highest potential

    1. Zone 1
    2. 2
    3. 3

    1 highest, 3 lowest

    EPA predicts over 4 pCi/L indoors

  • Rank in Maine

    10 of 16

    Middle half

    Kennebec
    30.3%
    York
    48.4%

    By share, of 16 with 30+ tests

Read a result for Kennebec County

Starts at Kennebec County's median, 2.1 pCi/L

2.1pCi/L

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

EPA’s reading of 2.1 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. Kennebec County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Kennebec County, At a glance

Kennebec County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Kennebec County in and predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county. That is one forecast for the whole county, not a reading of any address in it; homes above EPA's turn up in all three zones.

USGS geologic potential: High across 37% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

Radon tests reported for Kennebec County, 2008 to 2017, laboratory

Reported results by concentration band, Kennebec County, 2008 to 2017, laboratory
Under 2 pCi/L: 48%2 to 4 pCi/L: 22%4 pCi/L and above: 30%

Of 696 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Kennebec County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L33648.3%
2 to 4 pCi/L14921.4%
4 pCi/L and above21130.3%
What these figures count

These are the 696 tests reported to CDC for Kennebec County over 2008 to 2017 (laboratory totals), 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: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).

How to read these figures

Kennebec County, Compared

Kennebec County radon figures, compared

Calculated by Radon411

In Kennebec County, about 3 in 10 reported tests over the 2008 to 2017 laboratory totals (211 of 696) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 5.4 points lower. Across 16 Maine counties pooled together, 37.6% of tests reached that level, so Kennebec County runs 7.3 points below its state.

Of 6 neighbours with a figure, 3 reported a larger share at or above 4 pCi/L and 3 a smaller one; the spread is 18.8% (Somerset County) to 36.9% (Androscoggin County). By share, Kennebec County is 10th of 16 Maine counties with 30 or more tests for the same period.

Half the tests came in under 2.1 pCi/L and half over it; the single highest reached 152.1 pCi/L. Below the action level, 336 tests (48.3%) came in under 2 pCi/L, against 41.4% statewide, and 149 tests (21.4%) fell between 2 and 4, against 21.0% statewide.

Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 30.3% share point the same way here. USGS geology rates 37% of the county's land high radon potential. CDC also counts 6 tests taken after mitigation in Kennebec County for the same period: tests in homes where a fix was already in.

CDC's ten-year totals for Kennebec County went from 507 tests (2005 to 2014) to 696 (2008 to 2017), the share going from 29.2% to 30.3%.

Kennebec County against Maine, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Kennebec County
Kennebec County69630.3%2.1 pCi/LThis county
Maine, pooled16 counties, pooled11,82537.6%Not pooled+7.3 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+5.4 points
York Countyhighest in the state1,38948.4%3.7 pCi/L+18.1 points
Penobscot Countylowest in the state1,49116.4%0.8 pCi/L−13.9 points
Androscoggin County, MEborders it1,49736.9%2.8 pCi/L+6.6 points
Lincoln County, MEborders it24635.8%2.5 pCi/L+5.5 points
Waldo County, MEborders it20932.1%2.3 pCi/L+1.8 points
Sagadahoc County, MEborders it28330.0%2.1 pCi/L−0.3 points
Franklin County, MEborders it14129.1%1.8 pCi/L−1.2 points
Somerset County, MEborders it8518.8%1.5 pCi/L−11.5 points
Where Kennebec County's reported results fell, 2008 to 2017, laboratory, beside Maine and the United States
ResultKennebec County testsKennebec County shareMaine shareU.S. shareAgainst Maine
Under 2 pCi/L33648.3%41.4%39.6%+6.9 points
2 to 4 pCi/L14921.4%21.0%24.7%+0.4 points
4 pCi/L and above21130.3%37.6%35.7%−7.3 points
Kennebec County ranked among the 16 Maine counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Oxford County5 of 1639243.1%3.3 pCi/L
Hancock County6 of 1632739.1%2.6 pCi/L
Androscoggin County7 of 161,49736.9%2.8 pCi/L
Lincoln County8 of 1624635.8%2.5 pCi/L
Waldo County9 of 1620932.1%2.3 pCi/L
Kennebec County10 of 1669630.3%2.1 pCi/L
Sagadahoc County11 of 1628330.0%2.1 pCi/L
Washington County12 of 165429.6%1.6 pCi/L
Knox County13 of 1628729.6%2.3 pCi/L
Franklin County14 of 1614129.1%1.8 pCi/L
Somerset County15 of 168518.8%1.5 pCi/L
Kennebec County ten-year laboratory totals, against Maine's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestMaine, pooledChange from the row before
2008 to 201769630.3%2.1 pCi/L152.1 pCi/L37.6%+0.8 points
2007 to 201666429.5%2.0 pCi/L152.1 pCi/L37.6%−0.6 points
2006 to 201560130.1%2.0 pCi/L152.1 pCi/L37.6%+0.9 points
2005 to 201450729.2%2.0 pCi/L152.1 pCi/L36.6%First on file

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

Kennebec County, Geology

The ground under Kennebec County

Predicted

No class of ground holds half of Kennebec County on USGS's geologic map: 36.9% of its land is high radon potential, 32.7% moderate and 30.4% low. The map puts 32.7% of Kennebec County in the area it calls Moose River Lowlands/Central Maine Lowlands/Central Maine Highlands/Coastal Province and 30.4% in Coastal Province, with 3 smaller areas beside them. 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 Kennebec County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Moose River Lowlands/Central Maine Lowlands/Central Maine Highlands/Coastal ProvinceHeterogeneous metamorphic and igneous rocks.Moderate1132.7%
Coastal ProvinceGlacial lake clay and marine clay.Low830.4%
Central Maine HighlandsClastic and carbonate sedimentary rocks.High1424.1%
Moose River Lowlands/Central Maine Lowlands/Central Maine Highlands/Coastal ProvinceGranite and high grade metamorphic rocks.High1410.2%
Central Maine HighlandsMafic granite and alkalai feldspar granite.High142.7%

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

Kennebec County beside the ground around it

Kennebec County has more high-potential ground than Maine as a whole: 36.9% of its land against 24.5%. Of the 6 counties that border it, 1 has more high-potential ground, Androscoggin County the most at 67.7%.

Share of land by USGS radon potential: Kennebec County, the 6 counties bordering it and Maine
AreaEPA zoneLow potentialModerate potentialHigh potential
Kennebec CountyZone 130.4%32.7%36.9%
Androscoggin CountyZone 132.3%None67.7%
Lincoln CountyZone 178.2%8.8%None
Sagadahoc CountyZone 275.4%None10.5%
Waldo CountyZone 25.7%76.9%15.5%
Franklin CountyZone 10.3%65.1%34.5%
Somerset CountyZone 145.6%52.3%2.1%
Maine16 counties, pooled by land areaVaries35.9%38.3%24.5%

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

Local help

Kennebec County, Local resources

Radon testing and mitigation in Kennebec County

What Maine's program says
Phone
207-287-5676
Email
radon.dhhs@maine.gov
Licensing of radon professionals
Under Maine law, only the owner or occupant of a residence or someone registered with the state to provide these services, may test for radon, install and/or advise on the installation of a radon reduction (mitigation) system.

What it means

Kennebec County, Questions

Questions about radon in Kennebec County

Are radon levels high in Kennebec County?

Over the 2008 to 2017 laboratory totals, 30.3% of the radon tests reported to CDC for Kennebec County, Maine were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.1 pCi/L. Of 16 Maine counties with 30 or more tests for the same period, 9 reported a higher share; pooled, the state comes to 37.6%.

Which counties border Kennebec County?

Kennebec County borders 6 counties: Androscoggin County, Lincoln County, Sagadahoc County, Waldo County, Franklin County and Somerset County.

Products

Kennebec County, Products

Testing a home in Kennebec County

In Kennebec County, 30.3% of 696 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 37.6% pooled across Maine. In Zone 1 the year-round level in Kennebec County is the one to know: a long-term test (more than 90 days) or a monitor, with a short-term kit for a first answer.

Test kits and monitors3

See every kit and monitor

Kennebec County is in EPA Zone 1, the highest predicted radon potential. Best radon monitors for Zone 1 counties like Kennebec County

Explore

Kennebec County, Bordering counties

Counties bordering Kennebec County

Calculated by Radon411

Kennebec County, Cities and towns

Cities and towns in Kennebec County

The Census Bureau estimates 129,067 residents in Kennebec County for July 1, 2025, 4,335 more than in 2020 (+3.5%). That works out to 149 people per square mile of land. No town dominates: Augusta, the largest, has 19,155 residents, 14.8% of the total. Together its 4 incorporated places hold 35.3% of those residents; the other 64.7% live outside any of them. Reported testing is thin here: 696 tests over 2008 to 2017, or 5.4 for every 1,000 residents (2025 estimate), where Maine as a whole comes to 8.4.

From Augusta to Hallowell, CDC publishes no figure by town: each reads Kennebec County's.

The cities and towns in Kennebec County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Augusta19,155+1.2%14.8%
Waterville17,579+5.3%13.6%
Gardiner6,206+3.8%4.8%
Hallowell2,624+2.3%2.0%

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).

Kennebec County, Homes

Homes in Kennebec County

Of Kennebec County's 63,140 homes, 68% are detached houses, against 70% across Maine; 10% are mobile homes. Half of its homes were built before 1975, close to Maine's 1976: 34% date from before 1960 and 17% from 2000 or later. 73% of occupied homes are lived in by their owner (Maine: 74%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Kennebec County, Maine, 2019 to 2023
HomesKennebec CountyMaine
Housing units63,140746,552
Detached houses68%70%
In buildings of 5 or more10%9%
Mobile homes10%8%
Built before 196034%35%
Built since 200017%20%
Middle year built19751976
Owner-occupied73%74%

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