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Radon Levels in Hardin County, Kentucky

EPA puts Hardin County in Zone 2, its middle radon zone, and high results are common there: 50.3% of the 429 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

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  • Share at 4+ pCi/L

    50.3%

    6.6 pts above KY

    Hardin
    50.3%
    Kentucky
    43.7%

    429 tests, 2008 to 2017

  • Median result

    4.0pCi/L

    Action level reached

    Hardin
    4.0 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    429

    14th of 69 by tests

    Hardin
    429
    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

    16 of 69

    Top quarter

    Hardin
    50.3%
    Meade
    68.4%

    By share, of 69 with 30+ tests

Read a result for Hardin County

Starts at Hardin County's median, 4.0 pCi/L

4.0pCi/L

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

EPA’s reading of 4.0 pCi/L

At or above 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 at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. Hardin County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Hardin County, At a glance

Hardin County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Hardin 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 97% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, Hardin County, 2008 to 2017, laboratory
Under 2 pCi/L: 23%2 to 4 pCi/L: 26%4 pCi/L and above: 51%

Of 429 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Hardin County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L10023.3%
2 to 4 pCi/L11326.3%
4 pCi/L and above21650.3%
What these figures count

These are the 429 tests reported to CDC for Hardin 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

Hardin County, Compared

Hardin County radon figures, compared

Calculated by Radon411

More than half: 50.3% of the 429 radon tests reported to CDC for Hardin County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 16th of 69 Kentucky counties with 30 or more tests for the same period. That is 6.6 points above the 43.7% pooled from 120 Kentucky counties.

The median result, 4.0 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 90.1 pCi/L. The rest split 23.3% under 2 pCi/L and 26.3% from 2 to 4 (Kentucky: 33.2% and 23.1%). The reported tests do not follow EPA's Zone 2 label for Hardin County (predicted average between 2 and 4 pCi/L): 50.3% of them reached 4 pCi/L, fewer than that label suggests.

4 of its 9 bordering counties with figures ran higher, led by Meade County at 68.4%; Grayson County reported 27.8%. Statewide for the same period, Meade County reported the highest share (68.4%) and Hopkins County the lowest (9.5%).

CDC's ten-year totals for Hardin County went from 385 tests (2005 to 2014) to 429 (2008 to 2017), the share going from 53.5% to 50.3%.

Nationally, every county with a figure for the same period pools to 35.7%; Hardin County sits 14.6 points above it. CDC also counts 27 tests taken after mitigation in Hardin County for the same period: tests in homes where a fix was already in.

Hardin County against Kentucky, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Hardin County
Hardin County42950.3%4.0 pCi/LThis county
Kentucky, pooled120 counties, pooled28,79343.7%Not pooled−6.6 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−14.6 points
Warren Countyhighest in the state1,62461.5%6.3 pCi/L+11.2 points
Hopkins Countylowest in the state429.5%1.7 pCi/L−40.8 points
Meade County, KYborders it11768.4%8.2 pCi/L+18.1 points
Nelson County, KYborders it30466.1%6.3 pCi/L+15.8 points
Hart County, KYborders it8465.5%8.0 pCi/L+15.2 points
Harrison County, INborders it22162.4%5.5 pCi/L+12.1 points
Bullitt County, KYborders it55147.5%3.6 pCi/L−2.8 points
Larue County, KYborders it3447.1%3.7 pCi/L−3.2 points
Jefferson County, KYborders it6,59039.4%2.7 pCi/L−10.9 points
Breckinridge County, KYborders it3231.3%2.5 pCi/L−19.0 points
Grayson County, KYborders it3627.8%2.2 pCi/L−22.5 points
Where Hardin County's reported results fell, 2008 to 2017, laboratory, beside Kentucky and the United States
ResultHardin County testsHardin County shareKentucky shareU.S. shareAgainst Kentucky
Under 2 pCi/L10023.3%33.2%39.6%−9.9 points
2 to 4 pCi/L11326.3%23.1%24.7%+3.2 points
4 pCi/L and above21650.3%43.7%35.7%+6.6 points
Hardin 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
Boyle County11 of 6949253.9%4.4 pCi/L
Bourbon County12 of 6912753.5%4.8 pCi/L
Monroe County13 of 698752.9%4.6 pCi/L
Barren County14 of 6918651.6%4.0 pCi/L
Montgomery County15 of 6910551.4%4.1 pCi/L
Hardin County16 of 6942950.3%4.0 pCi/L
Marion County17 of 6917748.6%3.9 pCi/L
Bullitt County18 of 6955147.5%3.6 pCi/L
Clinton County19 of 694047.5%3.5 pCi/L
Larue County20 of 693447.1%3.7 pCi/L
Scott County21 of 6987546.9%3.6 pCi/L
Hardin County ten-year laboratory totals, against Kentucky's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestKentucky, pooledChange from the row before
2008 to 201742950.3%4.0 pCi/L90.1 pCi/L43.7%−1.5 points
2007 to 201642351.8%4.1 pCi/L90.1 pCi/L45.1%−0.8 points
2006 to 201540552.6%4.1 pCi/L90.1 pCi/L46.4%−0.9 points
2005 to 201438553.5%4.1 pCi/L90.1 pCi/L47.3%First on file

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

Hardin County, Geology

The ground under Hardin County

Predicted

Most of the ground under Hardin County is one class on USGS's geologic map: 96.6% of its land is moderate radon potential, with 3.4% high. 96.5% of it lies in the area the map calls Mississippian Plateau, to which USGS gives a radon index of 11, in the moderate band (9 to 11).

USGS's geologic areas under Hardin County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Mississippian PlateauMississippian marine limestones, dolomites, marine sandstones, siltstones, and shales.Moderate1196.5%
New Albany-Chattanooga ShaleDevonian/Mississippian Black shale.High143.4%

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

Hardin County beside the ground around it

Kentucky as a whole has more high-potential ground than Hardin County: 18.2% of its land, against 3.4% here. Of the 9 counties that border it, 4 have more high-potential ground, Bullitt County the most at 73.4%.

Share of land by USGS radon potential: Hardin County, the 9 counties bordering it and Kentucky
AreaEPA zoneLow potentialModerate potentialHigh potential
Hardin CountyZone 2None96.6%3.4%
Larue CountyZone 2None87.1%12.9%
Bullitt CountyZone 1None26.6%73.4%
Nelson CountyZone 1None45.9%54.1%
Grayson CountyZone 2None100%None
Meade CountyZone 2None100%None
Breckinridge CountyZone 2None100%None
Hart CountyZone 1None100%None
Harrison County, INZone 1None100%None
Jefferson CountyZone 1None44.9%55.1%
Kentucky120 counties, pooled by land areaVaries5.7%76.1%18.2%

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

Local help

Hardin County, Local resources

Radon testing and mitigation in Hardin County

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

What it means

Hardin County, Questions

Questions about radon in Hardin County

Are radon levels high in Hardin County?

Over the 2008 to 2017 laboratory totals, 50.3% of the radon tests reported to CDC for Hardin County, Kentucky were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.0 pCi/L. Of 69 Kentucky counties with 30 or more tests for the same period, 15 reported a higher share; pooled, the state comes to 43.7%.

Which counties border Hardin County?

Hardin County borders 9 counties: Larue County, KY, Bullitt County, KY, Nelson County, KY, Grayson County, KY, Meade County, KY, Breckinridge County, KY, Hart County, KY, Harrison County, IN and Jefferson County, KY.

Products

Hardin County, Products

Testing a home in Hardin County

In Hardin County, 50.3% of 429 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 Hardin County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Hardin County homes, compared

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Hardin County, Bordering counties

Counties bordering Hardin County

Calculated by Radon411

Hardin County, Cities and towns

Cities and towns in Hardin County

The Census Bureau estimates 113,482 residents in Hardin County for July 1, 2025, 2,648 more than in 2020 (+2.4%). That works out to 182 people per square mile of land. Its largest town, Elizabethtown, has 35,448 residents, 31.2% of the total. Reported testing is thin here: 429 tests over 2008 to 2017, or 3.8 for every 1,000 residents (2025 estimate), where Kentucky as a whole comes to 6.3.

From Elizabethtown to Sonora, CDC publishes no figure by town: each reads Hardin County's.

The cities and towns in Hardin County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Elizabethtown35,448+12.9%31.2%
Radcliff22,576−1.9%19.9%
Vine Grove7,018+6.2%6.2%
Muldraughextends beyond Hardin County1,009−2.7%Counted whole
West Point895−5.8%0.8%
Uptonextends beyond Hardin County702−0.8%Counted whole
Sonora564−2.8%0.5%

7 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 Hardin County is counted whole, so it has no share.

Hardin County, Homes

Homes in Hardin County

Of Hardin County's 47,370 homes, 65% are detached houses, against 68% across Kentucky; 12% are in buildings of five or more homes. Half of its homes were built before 1987, close to Kentucky's 1982: 15% date from before 1960 and 31% from 2000 or later. 62% 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 Hardin County, Kentucky, 2019 to 2023
HomesHardin CountyKentucky
Housing units47,3702,010,655
Detached houses65%68%
In buildings of 5 or more12%12%
Mobile homes9%11%
Built before 196015%22%
Built since 200031%24%
Middle year built19871982
Owner-occupied62%68%

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