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Radon Levels in Hart County, Kentucky

EPA puts Hart County in Zone 1, its highest radon zone, and high results are common there: 65.5% of the 84 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

    65.5%

    21.8 pts above KY

    Hart
    65.5%
    Kentucky
    43.7%

    84 tests, 2008 to 2017

  • Median result

    8.0pCi/L

    Action level reached

    Hart
    8.0 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    84

    40th of 69 by tests

    Hart
    84
    Jefferson
    6,590

    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 Kentucky

    3 of 69

    Top quarter

    Hart
    65.5%
    Meade
    68.4%

    By share, of 69 with 30+ tests

Read a result for Hart County

Starts at Hart County's median, 8.0 pCi/L

8.0pCi/L

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

EPA’s reading of 8.0 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. Hart County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Hart County, At a glance

Hart County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Hart 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 100% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, Hart County, 2008 to 2017, laboratory
Under 2 pCi/L: 14%2 to 4 pCi/L: 20%4 pCi/L and above: 66%

Of 84 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Hart County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L1214.3%
2 to 4 pCi/L1720.2%
4 pCi/L and above5565.5%
What these figures count

These are the 84 tests reported to CDC for Hart 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

Hart County, Compared

Hart County radon figures, compared

Calculated by Radon411

More than half: 65.5% of the 84 radon tests reported to CDC for Hart County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 3rd of 69 Kentucky counties with 30 or more tests for the same period. That is 21.8 points above the 43.7% pooled from 120 Kentucky counties.

The median result, 8.0 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 147.1 pCi/L. The rest split 14.3% under 2 pCi/L and 20.2% from 2 to 4 (Kentucky: 33.2% and 23.1%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 65.5% share point the same way here.

No bordering county with a figure for the same period reported a higher share; the closest is Barren County at 51.6%, the lowest Edmonson County at 21.0%. 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 Hart County went from 84 tests (2005 to 2014) to 84 (2008 to 2017), the share going from 71.4% to 65.5%.

Nationally, every county with a figure for the same period pools to 35.7%; Hart County sits 29.8 points above it.

Hart County against Kentucky, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Hart County
Hart County8465.5%8.0 pCi/LThis county
Kentucky, pooled120 counties, pooled28,79343.7%Not pooled−21.8 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−29.8 points
Meade Countyhighest in the state11768.4%8.2 pCi/L+2.9 points
Hopkins Countylowest in the state429.5%1.7 pCi/L−56.0 points
Barren County, KYborders it18651.6%4.0 pCi/L−13.9 points
Hardin County, KYborders it42950.3%4.0 pCi/L−15.2 points
Larue County, KYborders it3447.1%3.7 pCi/L−18.4 points
Metcalfe County, KYborders it3345.5%3.5 pCi/L−20.0 points
Green County, KYborders it3132.3%2.5 pCi/L−33.2 points
Grayson County, KYborders it3627.8%2.2 pCi/L−37.7 points
Edmonson County, KYborders it6221.0%1.6 pCi/L−44.5 points
Where Hart County's reported results fell, 2008 to 2017, laboratory, beside Kentucky and the United States
ResultHart County testsHart County shareKentucky shareU.S. shareAgainst Kentucky
Under 2 pCi/L1214.3%33.2%39.6%−18.9 points
2 to 4 pCi/L1720.2%23.1%24.7%−2.9 points
4 pCi/L and above5565.5%43.7%35.7%+21.8 points
Hart 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
Meade County1 of 6911768.4%8.2 pCi/L
Nelson County2 of 6930466.1%6.3 pCi/L
Hart County3 of 698465.5%8.0 pCi/L
Warren County4 of 691,62461.5%6.3 pCi/L
Wayne County5 of 696460.9%5.0 pCi/L
Pulaski County6 of 6939559.5%5.1 pCi/L
Woodford County7 of 6934257.9%4.9 pCi/L
Taylor County8 of 699157.1%4.4 pCi/L
Jessamine County9 of 6978955.5%4.7 pCi/L
Fayette County10 of 695,26354.5%4.5 pCi/L
Boyle County11 of 6949253.9%4.4 pCi/L
Hart County ten-year laboratory totals, against Kentucky's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestKentucky, pooledChange from the row before
2008 to 20178465.5%8.0 pCi/L147.1 pCi/L43.7%−2.0 points
2007 to 20168067.5%8.0 pCi/L147.1 pCi/L45.1%−4.1 points
2006 to 20158171.6%8.4 pCi/L147.1 pCi/L46.4%+0.2 points
2005 to 20148471.4%9.5 pCi/L147.1 pCi/L47.3%First on file

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

Hart County, Geology

The ground under Hart County

Predicted

USGS's geologic map puts all of Hart County's mapped land in one class: moderate radon potential. 97.4% 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 Hart County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Mississippian PlateauMississippian marine limestones, dolomites, marine sandstones, siltstones, and shales.Moderate1197.4%
Western CoalfieldLimestones, shale, siltstone, and coal beds.Moderate92.6%

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

Hart County beside the ground around it

Across Kentucky 18.2% of the land is rated high; none of Hart County's is. Of the 7 counties that border it, 5 have more high-potential ground, Metcalfe County the most at 77.4%.

Share of land by USGS radon potential: Hart County, the 7 counties bordering it and Kentucky
AreaEPA zoneLow potentialModerate potentialHigh potential
Hart CountyZone 1None100%None
Green CountyZone 1None33.4%66.5%
Edmonson CountyZone 2None100%None
Barren CountyZone 1None50.0%50.0%
Larue CountyZone 2None87.1%12.9%
Metcalfe CountyZone 1None22.6%77.4%
Grayson CountyZone 2None100%None
Hardin CountyZone 2None96.6%3.4%
Kentucky120 counties, pooled by land areaVaries5.7%76.1%18.2%

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

Local help

Hart County, Local resources

Radon testing and mitigation in Hart County

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

What it means

Hart County, Questions

Questions about radon in Hart County

Are radon levels high in Hart County?

Over the 2008 to 2017 laboratory totals, 65.5% of the radon tests reported to CDC for Hart County, Kentucky were at or above 4 pCi/L, and the median reported pre-mitigation result was 8.0 pCi/L. Of 69 Kentucky counties with 30 or more tests for the same period, 2 reported a higher share; pooled, the state comes to 43.7%.

Which counties border Hart County?

Hart County borders 7 counties: Green County, Edmonson County, Barren County, Larue County, Metcalfe County, Grayson County and Hardin County.

Products

Hart County, Products

Testing a home in Hart County

In Hart County, 65.5% of 84 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 43.7% pooled across Kentucky. In Zone 1 the year-round level in Hart 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

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

Explore

Hart County, Bordering counties

Counties bordering Hart County

Calculated by Radon411

Hart County, Cities and towns

Cities and towns in Hart County

The Census Bureau estimates 20,117 residents in Hart County for July 1, 2025, 829 more than in 2020 (+4.3%). That works out to 49 people per square mile of land. No town dominates: Horse Cave, the largest, has 2,276 residents, 11.3% of the total. Together its 3 incorporated places hold 21.3% of those residents; the other 78.7% live outside any of them. CDC's 84 reported tests for 2008 to 2017 work out to 4.2 per 1,000 residents (2025 estimate), close to Kentucky's 6.3.

From Horse Cave to Bonnieville, CDC publishes no figure by town: each reads Hart County's.

The cities and towns in Hart County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Horse Cave2,276+2.7%11.3%
Munfordville1,730+2.8%8.6%
Bonnieville275+3.8%1.4%

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).

Hart County, Homes

Homes in Hart County

Of Hart County's 8,888 homes, 72% are detached houses, against 68% across Kentucky; 19% are mobile homes. Half of its homes were built before 1984, close to Kentucky's 1982: 23% date from before 1960 and 28% from 2000 or later. 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 Hart County, Kentucky, 2019 to 2023
HomesHart CountyKentucky
Housing units8,8882,010,655
Detached houses72%68%
In buildings of 5 or more4%12%
Mobile homes19%11%
Built before 196023%22%
Built since 200028%24%
Middle year built19841982
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.