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Radon Levels in Carter County, Kentucky

EPA puts Carter County in Zone 2, its middle radon zone, and 31.7% of its 41 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

    31.7%

    12.0 pts below KY

    Carter
    31.7%
    Kentucky
    43.7%

    41 tests, 2008 to 2017

  • Median result

    2.2pCi/L

    Below action level

    Carter
    2.2 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    41

    59th of 69 by tests

    Carter
    41
    Jefferson
    6,590

    Reported to CDC before any fix, 2008 to 2017

  • 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 Kentucky

    42 of 69

    Middle half

    Carter
    31.7%
    Meade
    68.4%

    By share, of 69 with 30+ tests

Read a result for Carter County

Starts at Carter County's median, 2.2 pCi/L

2.2pCi/L

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

EPA’s reading of 2.2 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. Carter County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Carter County, At a glance

Carter County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Carter 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 100% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, Carter County, 2008 to 2017, laboratory
Under 2 pCi/L: 49%2 to 4 pCi/L: 19%4 pCi/L and above: 32%

Of 41 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Carter County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L2048.8%
2 to 4 pCi/L819.5%
4 pCi/L and above1331.7%
What these figures count

These are the 41 tests reported to CDC for Carter 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

Carter County, Compared

Carter County radon figures, compared

Calculated by Radon411

In Carter County, about 3 in 10 reported tests over the 2008 to 2017 laboratory totals (13 of 41) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 4.0 points lower. Across 120 Kentucky counties pooled together, 43.7% of tests reached that level, so Carter County runs 12.0 points below its state.

Of 3 neighbours with a figure, none reported a larger share at or above 4 pCi/L; the spread is 12.5% (Greenup County) to 18.9% (Rowan County). By share, Carter County is 42nd of 69 Kentucky counties with 30 or more tests for the same period.

Half the tests came in under 2.2 pCi/L and half over it; the single highest reached 19.4 pCi/L. Below the action level, 20 tests (48.8%) came in under 2 pCi/L, against 33.2% statewide, and 8 tests (19.5%) fell between 2 and 4, against 23.1% statewide.

Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 31.7% share point the same way here. USGS geology rates 100% of the county's land moderate radon potential.

CDC's ten-year totals for Carter County went from 21 tests (2005 to 2014) to 41 (2008 to 2017), the share going from 52.4% to 31.7%.

Carter County against Kentucky, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Carter County
Carter County4131.7%2.2 pCi/LThis county
Kentucky, pooled120 counties, pooled28,79343.7%Not pooled+12.0 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+4.0 points
Meade Countyhighest in the state11768.4%8.2 pCi/L+36.7 points
Hopkins Countylowest in the state429.5%1.7 pCi/L−22.2 points
Elliott County, KYborders it540.0%3.5 pCi/L+8.3 points
Lewis County, KYborders it1233.3%2.8 pCi/L+1.6 points
Rowan County, KYborders it7418.9%1.6 pCi/L−12.8 points
Boyd County, KYborders it16817.9%2.1 pCi/L−13.8 points
Greenup County, KYborders it10412.5%2.0 pCi/L−19.2 points
Lawrence County, KYborders it90.0%1.7 pCi/L−31.7 points
Where Carter County's reported results fell, 2008 to 2017, laboratory, beside Kentucky and the United States
ResultCarter County testsCarter County shareKentucky shareU.S. shareAgainst Kentucky
Under 2 pCi/L2048.8%33.2%39.6%+15.6 points
2 to 4 pCi/L819.5%23.1%24.7%−3.6 points
4 pCi/L and above1331.7%43.7%35.7%−12.0 points
Carter County ranked among the 69 Kentucky counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Lincoln County37 of 6913535.6%2.8 pCi/L
Grant County38 of 697833.3%2.5 pCi/L
Casey County39 of 694332.6%3.1 pCi/L
Simpson County40 of 6912632.5%2.6 pCi/L
Green County41 of 693132.3%2.5 pCi/L
Carter County42 of 694131.7%2.2 pCi/L
Logan County43 of 697931.6%2.4 pCi/L
Spencer County44 of 6916631.3%2.5 pCi/L
Breckinridge County45 of 693231.3%2.5 pCi/L
Allen County46 of 695829.3%1.9 pCi/L
Clark County47 of 6923129.0%2.4 pCi/L
Carter County ten-year laboratory totals, against Kentucky's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestKentucky, pooledChange from the row before
2008 to 20174131.7%2.2 pCi/L19.4 pCi/L43.7%−5.8 points
2007 to 20163237.5%2.6 pCi/L19.4 pCi/L45.1%−12.5 points
2006 to 20152450.0%3.6 pCi/L19.4 pCi/L46.4%−2.4 points
2005 to 20142152.4%4.0 pCi/L19.4 pCi/L47.3%First on file

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

Carter County, Geology

The ground under Carter County

Predicted

USGS's geologic map puts all of Carter County's mapped land in one class: moderate radon potential. The map puts 42.7% of Carter County in the area it calls Cumberland Plateau and 35.8% in Mississippian Plateau, with one smaller area beside them. USGS gives the first a radon index of 9 and the second 11, both in the moderate band (9 to 11).

USGS's geologic areas under Carter County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Cumberland PlateauPennsylvanian sandstones, siltstones, and shales.Moderate942.7%
Mississippian PlateauMississippian marine limestones, dolomites, marine sandstones, siltstones, and shales.Moderate1135.8%
Central Allegheny PlateauPermian and Pennsylvanian shale, siltstone, sandstone, minor limestone.Moderate1021.5%

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

Carter County beside the ground around it

Across Kentucky 18.2% of the land is rated high; none of Carter County's is. Of the 6 counties that border it, 3 have more high-potential ground, Lewis County the most at 40.8%.

Share of land by USGS radon potential: Carter County, the 6 counties bordering it and Kentucky
AreaEPA zoneLow potentialModerate potentialHigh potential
Carter CountyZone 2None100%None
Elliott CountyZone 2None100%None
Greenup CountyZone 2None99.5%0.5%
Boyd CountyZone 2None100%None
Rowan CountyZone 2None89.2%10.8%
Lawrence CountyZone 2None100%None
Lewis CountyZone 2None59.2%40.8%
Kentucky120 counties, pooled by land areaVaries5.7%76.1%18.2%

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

Local help

Carter County, Local resources

Radon testing and mitigation in Carter County

What Kentucky's program says
Phone
502-782-2782
Email
Radon@ky.gov

What it means

Carter County, Questions

Questions about radon in Carter County

Are radon levels high in Carter County?

Over the 2008 to 2017 laboratory totals, 31.7% of the radon tests reported to CDC for Carter County, Kentucky were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.2 pCi/L. Of 69 Kentucky counties with 30 or more tests for the same period, 41 reported a higher share; pooled, the state comes to 43.7%.

Which counties border Carter County?

Carter County borders 6 counties: Elliott County, Greenup County, Boyd County, Rowan County, Lawrence County and Lewis County.

Products

Carter County, Products

Testing a home in Carter County

In Carter County, 31.7% of 41 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 43.7% pooled across Kentucky. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Carter County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Carter County homes, compared

Explore

Carter County, Bordering counties

Counties bordering Carter County

Calculated by Radon411

Carter County, Cities and towns

Cities and towns in Carter County

About 26,149 people live in Carter County by the Census Bureau's estimate for July 1, 2025, 465 fewer than in 2020 (−1.7%). That works out to 64 people per square mile of land. No town dominates: Grayson, the largest, has 3,728 residents, 14.3% of the total. Together its 2 incorporated places hold 20.1% of those residents; the other 79.9% live outside any of them. Reported testing is thin here: 41 tests over 2008 to 2017, or 1.6 for every 1,000 residents (2025 estimate), where Kentucky as a whole comes to 6.3.

From Grayson to Olive Hill, CDC publishes no figure by town: each reads Carter County's.

The cities and towns in Carter County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Grayson3,728−2.8%14.3%
Olive Hill1,536−2.9%5.9%

2 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).

Carter County, Homes

Homes in Carter County

Of Carter County's 12,283 homes, 68% are detached houses, against 68% across Kentucky; 26% are mobile homes. Half of its homes were built before 1983, close to Kentucky's 1982: 17% date from before 1960 and 22% from 2000 or later. Owners live in 78% of the occupied homes (Kentucky: 68%), so for most households a test and a fix are their own to order.

Homes in Carter County, Kentucky, 2019 to 2023
HomesCarter CountyKentucky
Housing units12,2832,010,655
Detached houses68%68%
In buildings of 5 or more3%12%
Mobile homes26%11%
Built before 196017%22%
Built since 200022%24%
Middle year built19831982
Owner-occupied78%68%

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