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Radon Levels in York County, Maine

EPA puts York County in Zone 1, its highest radon zone, and high results are common there: 48.4% of the 1,389 radon tests reported to CDC (2008 to 2017, laboratory totals) came back 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

    48.4%

    10.8 pts above ME

    York
    48.4%
    Maine
    37.6%

    1,389 tests, 2008 to 2017

  • Median result

    3.7pCi/L

    Below action level

    York
    3.7 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    1,389

    4th of 16 by tests

    York
    1,389
    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

    1 of 16

    Top quarter

    York
    48.4%
    York
    48.4%

    By share, of 16 with 30+ tests

Read a result for York County

Starts at York County's median, 3.7 pCi/L

3.7pCi/L

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

EPA’s reading of 3.7 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. York County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

York County, At a glance

York County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of York 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 99% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, York County, 2008 to 2017, laboratory
Under 2 pCi/L: 31%2 to 4 pCi/L: 21%4 pCi/L and above: 48%

Of 1,389 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, York County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L43431.2%
2 to 4 pCi/L28320.4%
4 pCi/L and above67248.4%
What these figures count

These are the 1,389 tests reported to CDC for York 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

York County, Compared

York County radon figures, compared

Calculated by Radon411

In York County, about 5 in 10 reported tests over the 2008 to 2017 laboratory totals (672 of 1,389) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 12.7 points higher. Across 16 Maine counties pooled together, 37.6% of tests reached that level, so York County runs 10.8 points above its state.

Of 5 neighbours with a figure, none reported a larger share at or above 4 pCi/L; the spread is 41.9% (Rockingham County, NH) to 48.2% (Carroll County, NH). By share, York County is 1st of 16 Maine counties with 30 or more tests for the same period.

Half the tests came in under 3.7 pCi/L and half over it; the single highest reached 187.9 pCi/L. Below the action level, 434 tests (31.2%) came in under 2 pCi/L, against 41.4% statewide, and 283 tests (20.4%) fell between 2 and 4, against 21.0% statewide.

Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 48.4% share point the same way here. USGS geology rates 99% of the county's land high radon potential. CDC also counts 13 tests taken after mitigation in York County for the same period: tests in homes where a fix was already in.

CDC's ten-year totals for York County went from 996 tests (2005 to 2014) to 1,389 (2008 to 2017), the share going from 47.7% to 48.4%.

York County against Maine, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from York County
York County1,38948.4%3.7 pCi/LThis county
Maine, pooled16 counties, pooled11,82537.6%Not pooled−10.8 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−12.7 points
Piscataquis Countyhighest in the state4447.7%3.5 pCi/L−0.7 points
Penobscot Countylowest in the state1,49116.4%0.8 pCi/L−32.0 points
Carroll County, NHborders it42548.2%3.5 pCi/L−0.2 points
Cumberland County, MEborders it4,07643.5%3.2 pCi/L−4.9 points
Oxford County, MEborders it39243.1%3.3 pCi/L−5.3 points
Strafford County, NHborders it87042.5%3.1 pCi/L−5.9 points
Rockingham County, NHborders it4,07741.9%3.1 pCi/L−6.5 points
Where York County's reported results fell, 2008 to 2017, laboratory, beside Maine and the United States
ResultYork County testsYork County shareMaine shareU.S. shareAgainst Maine
Under 2 pCi/L43431.2%41.4%39.6%−10.2 points
2 to 4 pCi/L28320.4%21.0%24.7%−0.6 points
4 pCi/L and above67248.4%37.6%35.7%+10.8 points
York 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
York County ten-year laboratory totals, against Maine's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestMaine, pooledChange from the row before
2008 to 20171,38948.4%3.7 pCi/L187.9 pCi/L37.6%+0.2 points
2007 to 20161,31448.2%3.7 pCi/L187.9 pCi/L37.6%−0.1 points
2006 to 20151,16548.3%3.8 pCi/L187.9 pCi/L37.6%+0.6 points
2005 to 201499647.7%3.7 pCi/L187.9 pCi/L36.6%First on file

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

York County, Geology

The ground under York County

Predicted

Most of the ground under York County is one class on USGS's geologic map: 99.1% of its land is high radon potential, with 0.1% moderate. 99.1% of it lies in the area the map calls Moose River Lowlands/Central Maine Lowlands/Central Maine Highlands/Coastal Province, to which USGS gives a radon index of 14, in the high band (12 to 17).

USGS's geologic areas under York County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Moose River Lowlands/Central Maine Lowlands/Central Maine Highlands/Coastal ProvinceGranite and high grade metamorphic rocks.High1499.1%

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

York County beside the ground around it

York County has more high-potential ground than Maine as a whole: 99.1% of its land against 24.5%. Of the 5 counties that border it, none has as large a share of high-potential ground; Cumberland County comes nearest at 85.5%.

Share of land by USGS radon potential: York County, the 5 counties bordering it and Maine
AreaEPA zoneLow potentialModerate potentialHigh potential
York CountyZone 1None0.1%99.1%
Strafford County, NHZone 20.1%73.6%25.5%
Cumberland CountyZone 110.1%None85.5%
Rockingham County, NHZone 2None75.0%23.0%
Carroll County, NHZone 116.2%38.0%45.9%
Oxford CountyZone 1None14.9%85.1%
Maine16 counties, pooled by land areaVaries35.9%38.3%24.5%

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

Local help

York County, Local resources

Radon testing and mitigation in York 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

York County, Questions

Questions about radon in York County

Are radon levels high in York County?

Over the 2008 to 2017 laboratory totals, 48.4% of the radon tests reported to CDC for York County, Maine were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.7 pCi/L. Of 16 Maine counties with 30 or more tests for the same period, none reported a higher share; pooled, the state comes to 37.6%.

Which counties border York County?

York County borders 5 counties: Strafford County, NH, Cumberland County, ME, Rockingham County, NH, Carroll County, NH and Oxford County, ME.

Products

York County, Products

Testing a home in York County

In York County, 48.4% of 1,389 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 York 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

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

Explore

York County, Bordering counties

Counties bordering York County

Calculated by Radon411

York County, Cities and towns

Cities and towns in York County

The Census Bureau estimates 222,434 residents in York County for July 1, 2025, 10,162 more than in 2020 (+4.8%). That works out to 224 people per square mile of land. No town dominates: Sanford, the largest, has 22,663 residents, 10.2% of the total. Together its 3 incorporated places hold 29.8% of those residents; the other 70.2% live outside any of them. CDC's 1,389 reported tests for 2008 to 2017 work out to 6.2 per 1,000 residents (2025 estimate), close to Maine's 8.4.

From Sanford to Saco, CDC publishes no figure by town: each reads York County's.

The cities and towns in York County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Sanford22,663+3.2%10.2%
Biddeford22,399−0.7%10.1%
Saco21,159+3.6%9.5%

3 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).

York County, Homes

Homes in York County

Of York County's 113,853 homes, 70% are detached houses, against 70% across Maine; 8% are in buildings of five or more homes. Half of its homes were built before 1979, close to Maine's 1976: 32% date from before 1960 and 22% from 2000 or later. Owners live in 76% of the occupied homes (Maine: 74%), so for most households a test and a fix are their own to order.

Homes in York County, Maine, 2019 to 2023
HomesYork CountyMaine
Housing units113,853746,552
Detached houses70%70%
In buildings of 5 or more8%9%
Mobile homes6%8%
Built before 196032%35%
Built since 200022%20%
Middle year built19791976
Owner-occupied76%74%

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