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Radon Levels in Grant County, Kentucky

EPA puts Grant County in Zone 2, its middle radon zone, and 33.3% of its 78 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

    33.3%

    10.4 pts below KY

    Grant
    33.3%
    Kentucky
    43.7%

    78 tests, 2008 to 2017

  • Median result

    2.5pCi/L

    Below action level

    Grant
    2.5 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    78

    43rd of 69 by tests

    Grant
    78
    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

    38 of 69

    Middle half

    Grant
    33.3%
    Meade
    68.4%

    By share, of 69 with 30+ tests

Read a result for Grant County

Starts at Grant County's median, 2.5 pCi/L

2.5pCi/L

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

EPA’s reading of 2.5 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. Grant County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Grant County, At a glance

Grant County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Grant 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 Grant County, 2008 to 2017, laboratory

Reported results by concentration band, Grant County, 2008 to 2017, laboratory
Under 2 pCi/L: 35%2 to 4 pCi/L: 32%4 pCi/L and above: 33%

Of 78 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Grant County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L2734.6%
2 to 4 pCi/L2532.1%
4 pCi/L and above2633.3%
What these figures count

These are the 78 tests reported to CDC for Grant 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

Grant County, Compared

Grant County radon figures, compared

Calculated by Radon411

In Grant County, about 3 in 10 reported tests over the 2008 to 2017 laboratory totals (26 of 78) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 2.4 points lower. Across 120 Kentucky counties pooled together, 43.7% of tests reached that level, so Grant County runs 10.4 points below its state.

Of 6 neighbours with a figure, 4 reported a larger share at or above 4 pCi/L and 2 a smaller one; the spread is 26.0% (Kenton County) to 46.9% (Scott County). By share, Grant County is 38th of 69 Kentucky counties with 30 or more tests for the same period.

Half the tests came in under 2.5 pCi/L and half over it; the single highest reached 14.7 pCi/L. Below the action level, 27 tests (34.6%) came in under 2 pCi/L, against 33.2% statewide, and 25 tests (32.1%) 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 33.3% share point the same way here. USGS geology rates 100% of the county's land moderate radon potential. CDC also counts 5 tests taken after mitigation in Grant County for the same period: tests in homes where a fix was already in.

CDC's ten-year totals for Grant County went from 46 tests (2005 to 2014) to 78 (2008 to 2017), the share going from 34.8% to 33.3%.

Grant County against Kentucky, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Grant County
Grant County7833.3%2.5 pCi/LThis county
Kentucky, pooled120 counties, pooled28,79343.7%Not pooled+10.4 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+2.4 points
Meade Countyhighest in the state11768.4%8.2 pCi/L+35.1 points
Hopkins Countylowest in the state429.5%1.7 pCi/L−23.8 points
Scott County, KYborders it87546.9%3.6 pCi/L+13.6 points
Harrison County, KYborders it11146.8%3.4 pCi/L+13.5 points
Boone County, KYborders it1,43442.9%3.5 pCi/L+9.6 points
Owen County, KYborders it5836.2%2.5 pCi/L+2.9 points
Pendleton County, KYborders it3426.5%1.9 pCi/L−6.8 points
Kenton County, KYborders it1,16726.0%2.3 pCi/L−7.3 points
Gallatin County, KYborders it2425.0%2.5 pCi/L−8.3 points
Where Grant County's reported results fell, 2008 to 2017, laboratory, beside Kentucky and the United States
ResultGrant County testsGrant County shareKentucky shareU.S. shareAgainst Kentucky
Under 2 pCi/L2734.6%33.2%39.6%+1.4 points
2 to 4 pCi/L2532.1%23.1%24.7%+9.0 points
4 pCi/L and above2633.3%43.7%35.7%−10.4 points
Grant 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
Oldham County33 of 6980337.1%2.7 pCi/L
Henry County34 of 694136.6%3.2 pCi/L
Owen County35 of 695836.2%2.5 pCi/L
Christian County36 of 697236.1%3.2 pCi/L
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
Grant County ten-year laboratory totals, against Kentucky's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestKentucky, pooledChange from the row before
2008 to 20177833.3%2.5 pCi/L14.7 pCi/L43.7%+2.4 points
2007 to 20166830.9%2.4 pCi/L14.5 pCi/L45.1%−4.3 points
2006 to 20155435.2%2.4 pCi/L14.5 pCi/L46.4%+0.4 points
2005 to 20144634.8%2.4 pCi/L12.1 pCi/L47.3%First on file

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

Grant County, Geology

The ground under Grant County

Predicted

USGS's geologic map puts all of Grant County's mapped land in one class: moderate radon potential. All of it lies in the area the map calls Outer Bluegrass, to which USGS gives a radon index of 11, in the moderate band (9 to 11).

USGS's geologic areas under Grant County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Outer BluegrassOrdovician-Devonian limestone and shale.Moderate11100%

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

Grant County beside the ground around it

Across Kentucky 18.2% of the land is rated high; none of Grant County's is. Of the 7 counties that border it, 5 have more high-potential ground, Scott County the most at 50.7%.

Share of land by USGS radon potential: Grant County, the 7 counties bordering it and Kentucky
AreaEPA zoneLow potentialModerate potentialHigh potential
Grant CountyZone 2None100%None
Owen CountyZone 2None98.1%1.9%
Gallatin CountyZone 2None100%None
Pendleton CountyZone 1None60.2%39.8%
Boone CountyZone 2None100%None
Kenton CountyZone 2None81.3%18.7%
Scott CountyZone 1None49.3%50.7%
Harrison CountyZone 1None65.3%34.7%
Kentucky120 counties, pooled by land areaVaries5.7%76.1%18.2%

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

Local help

Grant County, Local resources

Radon testing and mitigation in Grant County

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

What it means

Grant County, Questions

Questions about radon in Grant County

Are radon levels high in Grant County?

Over the 2008 to 2017 laboratory totals, 33.3% of the radon tests reported to CDC for Grant County, Kentucky were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.5 pCi/L. Of 69 Kentucky counties with 30 or more tests for the same period, 37 reported a higher share; pooled, the state comes to 43.7%.

Which counties border Grant County?

Grant County borders 7 counties: Owen County, Gallatin County, Pendleton County, Boone County, Kenton County, Scott County and Harrison County.

Products

Grant County, Products

Testing a home in Grant County

In Grant County, 33.3% of 78 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 Grant County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Grant County homes, compared

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Grant County, Bordering counties

Counties bordering Grant County

Calculated by Radon411

Grant County, Cities and towns

Cities and towns in Grant County

The Census Bureau estimates 26,181 residents in Grant County for July 1, 2025, 1,167 more than in 2020 (+4.7%). That works out to 101 people per square mile of land. Crittenden, the largest place on its list (4,185 residents in all), extends beyond Grant County, so no share of the total is worked out for it. Reported testing is thin here: 78 tests over 2008 to 2017, or 3.0 for every 1,000 residents (2025 estimate), where Kentucky as a whole comes to 6.3.

From Crittenden to Corinth, CDC publishes no figure by town: each reads Grant County's.

The cities and towns in Grant County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Crittendenextends beyond Grant County4,185+3.8%Counted whole
Williamstownextends beyond Grant County4,030+2.9%Counted whole
Dry Ridge2,249+3.5%8.6%
Corinthextends beyond Grant County237+3.5%Counted whole

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). A place that extends beyond Grant County is counted whole, so it has no share.

Grant County, Homes

Homes in Grant County

Of Grant County's 10,182 homes, 63% are detached houses, against 68% across Kentucky; 21% are mobile homes. Much of Grant County is recent building: 27% of its homes have gone up since 2000 and the middle year built is 1990, against 1982 for Kentucky. 74% of occupied homes are lived in by their owner (Kentucky: 68%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Grant County, Kentucky, 2019 to 2023
HomesGrant CountyKentucky
Housing units10,1822,010,655
Detached houses63%68%
In buildings of 5 or more7%12%
Mobile homes21%11%
Built before 196013%22%
Built since 200027%24%
Middle year built19901982
Owner-occupied74%68%

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