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Radon Levels in Nelson County, Kentucky

EPA puts Nelson County in Zone 1, its highest radon zone, and high results are common there: 66.1% of the 304 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

    66.1%

    22.4 pts above KY

    Nelson
    66.1%
    Kentucky
    43.7%

    304 tests, 2008 to 2017

  • Median result

    6.3pCi/L

    Action level reached

    Nelson
    6.3 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    304

    18th of 69 by tests

    Nelson
    304
    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

    2 of 69

    Top quarter

    Nelson
    66.1%
    Meade
    68.4%

    By share, of 69 with 30+ tests

Read a result for Nelson County

Starts at Nelson County's median, 6.3 pCi/L

6.3pCi/L

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

EPA’s reading of 6.3 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. Nelson County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Nelson County, At a glance

Nelson County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Nelson 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 54% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, Nelson County, 2008 to 2017, laboratory
Under 2 pCi/L: 19%2 to 4 pCi/L: 15%4 pCi/L and above: 66%

Of 304 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Nelson County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L5819.1%
2 to 4 pCi/L4514.8%
4 pCi/L and above20166.1%
What these figures count

These are the 304 tests reported to CDC for Nelson 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

Nelson County, Compared

Nelson County radon figures, compared

Calculated by Radon411

More than half: 66.1% of the 304 radon tests reported to CDC for Nelson County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 2nd of 69 Kentucky counties with 30 or more tests for the same period. That is 22.4 points above the 43.7% pooled from 120 Kentucky counties.

The median result, 6.3 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 122.6 pCi/L. The rest split 19.1% under 2 pCi/L and 14.8% from 2 to 4 (Kentucky: 33.2% and 23.1%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 66.1% share point the same way here.

No bordering county with a figure for the same period reported a higher share; the closest is Hardin County at 50.3%, the lowest Anderson County at 25.2%. 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 Nelson County went from 237 tests (2005 to 2014) to 304 (2008 to 2017), the share going from 69.6% to 66.1%.

Nationally, every county with a figure for the same period pools to 35.7%; Nelson County sits 30.4 points above it. CDC also counts 14 tests taken after mitigation in Nelson County for the same period: tests in homes where a fix was already in.

Nelson County against Kentucky, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Nelson County
Nelson County30466.1%6.3 pCi/LThis county
Kentucky, pooled120 counties, pooled28,79343.7%Not pooled−22.4 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−30.4 points
Meade Countyhighest in the state11768.4%8.2 pCi/L+2.3 points
Hopkins Countylowest in the state429.5%1.7 pCi/L−56.6 points
Hardin County, KYborders it42950.3%4.0 pCi/L−15.8 points
Marion County, KYborders it17748.6%3.9 pCi/L−17.5 points
Bullitt County, KYborders it55147.5%3.6 pCi/L−18.6 points
Larue County, KYborders it3447.1%3.7 pCi/L−19.0 points
Spencer County, KYborders it16631.3%2.5 pCi/L−34.8 points
Washington County, KYborders it4427.3%2.4 pCi/L−38.8 points
Anderson County, KYborders it22625.2%2.2 pCi/L−40.9 points
Where Nelson County's reported results fell, 2008 to 2017, laboratory, beside Kentucky and the United States
ResultNelson County testsNelson County shareKentucky shareU.S. shareAgainst Kentucky
Under 2 pCi/L5819.1%33.2%39.6%−14.1 points
2 to 4 pCi/L4514.8%23.1%24.7%−8.3 points
4 pCi/L and above20166.1%43.7%35.7%+22.4 points
Nelson 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
Nelson County ten-year laboratory totals, against Kentucky's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestKentucky, pooledChange from the row before
2008 to 201730466.1%6.3 pCi/L122.6 pCi/L43.7%−0.1 points
2007 to 201628466.2%6.4 pCi/L122.6 pCi/L45.1%−1.5 points
2006 to 201526367.7%6.6 pCi/L122.6 pCi/L46.4%−1.9 points
2005 to 201423769.6%7.3 pCi/L122.6 pCi/L47.3%First on file

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

Nelson County, Geology

The ground under Nelson County

Predicted

USGS's geologic map splits Nelson County: 54.1% of its land is high radon potential and 45.9% moderate. The map puts 54.1% of Nelson County in the area it calls New Albany-Chattanooga Shale and 45.7% in Outer Bluegrass. USGS gives the first a radon index of 14, in the high band (12 to 17), and the second 11, in the moderate band (9 to 11).

USGS's geologic areas under Nelson County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
New Albany-Chattanooga ShaleDevonian/Mississippian Black shale.High1454.1%
Outer BluegrassOrdovician-Devonian limestone and shale.Moderate1145.7%

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

Nelson County beside the ground around it

Nelson County has more high-potential ground than Kentucky as a whole: 54.1% of its land against 18.2%. Of the 7 counties that border it, 2 have more high-potential ground, Bullitt County the most at 73.4%.

Share of land by USGS radon potential: Nelson County, the 7 counties bordering it and Kentucky
AreaEPA zoneLow potentialModerate potentialHigh potential
Nelson CountyZone 1None45.9%54.1%
Larue CountyZone 2None87.1%12.9%
Bullitt CountyZone 1None26.6%73.4%
Marion CountyZone 1None32.3%67.7%
Washington CountyZone 2None100%None
Hardin CountyZone 2None96.6%3.4%
Spencer CountyZone 2None100%None
Anderson CountyZone 2None69.0%31.0%
Kentucky120 counties, pooled by land areaVaries5.7%76.1%18.2%

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

Local help

Nelson County, Local resources

Radon testing and mitigation in Nelson County

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

What it means

Nelson County, Questions

Questions about radon in Nelson County

Are radon levels high in Nelson County?

Over the 2008 to 2017 laboratory totals, 66.1% of the radon tests reported to CDC for Nelson County, Kentucky were at or above 4 pCi/L, and the median reported pre-mitigation result was 6.3 pCi/L. Of 69 Kentucky counties with 30 or more tests for the same period, 1 reported a higher share; pooled, the state comes to 43.7%.

Which counties border Nelson County?

Nelson County borders 7 counties: Larue County, Bullitt County, Marion County, Washington County, Hardin County, Spencer County and Anderson County.

Products

Nelson County, Products

Testing a home in Nelson County

In Nelson County, 66.1% of 304 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 Nelson 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

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

Explore

Nelson County, Bordering counties

Counties bordering Nelson County

Calculated by Radon411

Nelson County, Cities and towns

Cities and towns in Nelson County

The Census Bureau estimates 49,036 residents in Nelson County for July 1, 2025, 2,251 more than in 2020 (+4.8%). That works out to 117 people per square mile of land. Its largest town, Bardstown, has 14,161 residents, 28.9% of the total. Together its 4 incorporated places hold 32.9% of those residents; the other 67.1% live outside any of them. CDC's 304 reported tests for 2008 to 2017 work out to 6.2 per 1,000 residents (2025 estimate), close to Kentucky's 6.3.

From Bardstown to Fairfield, CDC publishes no figure by town: each reads Nelson County's.

The cities and towns in Nelson County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Bardstown14,161+4.3%28.9%
Bloomfield1,011+4.9%2.1%
New Haven837+4.2%1.7%
Fairfield138+16.0%0.3%

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).

Nelson County, Homes

Homes in Nelson County

Nelson County is a place of houses on their own lots: 81% of its 20,062 homes are detached single-family houses, against 68% across Kentucky. Much of Nelson County is recent building: 32% of its homes have gone up since 2000 and the middle year built is 1990, against 1982 for Kentucky. Owners live in 77% of the occupied homes (Kentucky: 68%), so for most households a test and a fix are their own to order.

Homes in Nelson County, Kentucky, 2019 to 2023
HomesNelson CountyKentucky
Housing units20,0622,010,655
Detached houses81%68%
In buildings of 5 or more5%12%
Mobile homes7%11%
Built before 196014%22%
Built since 200032%24%
Middle year built19901982
Owner-occupied77%68%

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