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Radon Levels in Hancock County, Maine

EPA puts Hancock County in Zone 1, its highest radon zone, and 39.1% of its 327 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

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    39.1%

    1.5 pts above ME

    Hancock
    39.1%
    Maine
    37.6%

    327 tests, 2008 to 2017

  • Median result

    2.6pCi/L

    Below action level

    Hancock
    2.6 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    327

    8th of 16 by tests

    Hancock
    327
    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

    6 of 16

    Middle half

    Hancock
    39.1%
    York
    48.4%

    By share, of 16 with 30+ tests

Read a result for Hancock County

Starts at Hancock County's median, 2.6 pCi/L

2.6pCi/L

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

EPA’s reading of 2.6 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. Hancock County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Hancock County, At a glance

Hancock County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Hancock 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: Moderate across 49% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, Hancock County, 2008 to 2017, laboratory
Under 2 pCi/L: 44%2 to 4 pCi/L: 17%4 pCi/L and above: 39%

Of 327 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Hancock County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L14243.4%
2 to 4 pCi/L5717.4%
4 pCi/L and above12839.1%
What these figures count

These are the 327 tests reported to CDC for Hancock 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

Hancock County, Compared

Hancock County radon figures, compared

Calculated by Radon411

In Hancock County, about 4 in 10 reported tests over the 2008 to 2017 laboratory totals (128 of 327) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 3.4 points higher. Across 16 Maine counties pooled together, 37.6% of tests reached that level, so Hancock County runs 1.5 points above its state.

Of 4 neighbours with a figure, none reported a larger share at or above 4 pCi/L; the spread is 16.4% (Penobscot County) to 32.1% (Waldo County). By share, Hancock County is 6th of 16 Maine counties with 30 or more tests for the same period.

Half the tests came in under 2.6 pCi/L and half over it; the single highest reached 75.6 pCi/L. Below the action level, 142 tests (43.4%) came in under 2 pCi/L, against 41.4% statewide, and 57 tests (17.4%) fell between 2 and 4, against 21.0% statewide.

Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 39.1% share point the same way here. USGS geology rates 49% of the county's land moderate radon potential. CDC also counts 6 tests taken after mitigation in Hancock County for the same period: tests in homes where a fix was already in.

CDC's ten-year totals for Hancock County went from 258 tests (2005 to 2014) to 327 (2008 to 2017), the share going from 45.7% to 39.1%.

Hancock County against Maine, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Hancock County
Hancock County32739.1%2.6 pCi/LThis county
Maine, pooled16 counties, pooled11,82537.6%Not pooled−1.5 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−3.4 points
York Countyhighest in the state1,38948.4%3.7 pCi/L+9.3 points
Somerset Countylowest in the state8518.8%1.5 pCi/L−20.3 points
Waldo County, MEborders it20932.1%2.3 pCi/L−7.0 points
Washington County, MEborders it5429.6%1.6 pCi/L−9.5 points
Knox County, MEborders it28729.6%2.3 pCi/L−9.5 points
Penobscot County, MEborders it1,49116.4%0.8 pCi/L−22.7 points
Where Hancock County's reported results fell, 2008 to 2017, laboratory, beside Maine and the United States
ResultHancock County testsHancock County shareMaine shareU.S. shareAgainst Maine
Under 2 pCi/L14243.4%41.4%39.6%+2.0 points
2 to 4 pCi/L5717.4%21.0%24.7%−3.6 points
4 pCi/L and above12839.1%37.6%35.7%+1.5 points
Hancock 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
York County1 of 161,38948.4%3.7 pCi/L
Piscataquis County2 of 164447.7%3.5 pCi/L
Aroostook County3 of 1660845.1%3.5 pCi/L
Cumberland County4 of 164,07643.5%3.2 pCi/L
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
Hancock County ten-year laboratory totals, against Maine's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestMaine, pooledChange from the row before
2008 to 201732739.1%2.6 pCi/L75.6 pCi/L37.6%−1.3 points
2007 to 201632740.4%2.7 pCi/L75.6 pCi/L37.6%−4.1 points
2006 to 201528144.5%3.3 pCi/L75.6 pCi/L37.6%−1.2 points
2005 to 201425845.7%3.4 pCi/L75.6 pCi/L36.6%First on file

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

Hancock County, Geology

The ground under Hancock County

Predicted

No class of ground holds half of Hancock County on USGS's geologic map: 49.1% of its land is moderate radon potential, 43.4% high and 1.5% low. The map puts 49.1% of Hancock County in the area it calls Moose River Lowlands/Central Maine Lowlands/Central Maine Highlands/Coastal Province and 29.5% 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 13, in the high band (12 to 17).

USGS's geologic areas under Hancock 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.Moderate1149.1%
Coastal ProvinceGranodiorite to syenite.High1329.5%
Coastal ProvinceGranite, granodiorite, and mafic metamorphic rocks.High1314.0%
Coastal ProvinceGlacial lake clay and marine clay.Low80.8%
Central Maine HighlandsGlacial lake clay and marine clay.Low80.7%

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

Hancock County beside the ground around it

Hancock County has more high-potential ground than Maine as a whole: 43.4% of its land against 24.5%. Of the 4 counties that border it, 1 has more high-potential ground, Knox County the most at 60.1%.

Share of land by USGS radon potential: Hancock County, the 4 counties bordering it and Maine
AreaEPA zoneLow potentialModerate potentialHigh potential
Hancock CountyZone 11.5%49.1%43.4%
Waldo CountyZone 25.7%76.9%15.5%
Washington CountyZone 230.8%45.5%19.3%
Knox CountyZone 29.2%18.6%60.1%
Penobscot CountyZone 129.7%66.2%4.0%
Maine16 counties, pooled by land areaVaries35.9%38.3%24.5%

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

Local help

Hancock County, Local resources

Radon testing and mitigation in Hancock 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

Hancock County, Questions

Questions about radon in Hancock County

Are radon levels high in Hancock County?

Over the 2008 to 2017 laboratory totals, 39.1% of the radon tests reported to CDC for Hancock County, Maine were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.6 pCi/L. Of 16 Maine counties with 30 or more tests for the same period, 5 reported a higher share; pooled, the state comes to 37.6%.

Which counties border Hancock County?

Hancock County borders 4 counties: Waldo County, Washington County, Knox County and Penobscot County.

Products

Hancock County, Products

Testing a home in Hancock County

In Hancock County, 39.1% of 327 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 Hancock 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

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

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Hancock County, Bordering counties

Counties bordering Hancock County

Calculated by Radon411

Hancock County, Cities and towns

Cities and towns in Hancock County

The Census Bureau estimates 57,171 residents in Hancock County for July 1, 2025, 1,659 more than in 2020 (+3.0%). That works out to 36 people per square mile of land. Ellsworth, its one incorporated place, has 8,862 residents, 15.5% of the total. CDC's 327 reported tests for 2008 to 2017 work out to 5.7 per 1,000 residents (2025 estimate), close to Maine's 8.4.

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

Ellsworth, Hancock County: residents on July 1, 2025
PlaceResidentsSince 2020Share of residents
Ellsworth8,862+5.3%15.5%

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).

Hancock County, Homes

Homes in Hancock County

Hancock County is a place of houses on their own lots: 81% of its 40,514 homes are detached single-family houses, against 70% across Maine. Half of its homes were built before 1981, close to Maine's 1976: 31% date from before 1960 and 24% from 2000 or later. Owners live in 79% of the occupied homes (Maine: 74%), so for most households a test and a fix are their own to order.

Homes in Hancock County, Maine, 2019 to 2023
HomesHancock CountyMaine
Housing units40,514746,552
Detached houses81%70%
In buildings of 5 or more5%9%
Mobile homes7%8%
Built before 196031%35%
Built since 200024%20%
Middle year built19811976
Owner-occupied79%74%

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