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Radon Levels in Warren County, Kentucky

EPA puts Warren County in Zone 1, its highest radon zone, and high results are common there: 61.5% of the 1,624 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

    61.5%

    17.8 pts above KY

    Warren
    61.5%
    Kentucky
    43.7%

    1,624 tests, 2008 to 2017

  • Median result

    6.3pCi/L

    Action level reached

    Warren
    6.3 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    1,624

    3rd of 69 by tests

    Warren
    1,624
    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

    4 of 69

    Top quarter

    Warren
    61.5%
    Meade
    68.4%

    By share, of 69 with 30+ tests

Read a result for Warren County

Starts at Warren 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. Warren County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Warren County, At a glance

Warren County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Warren 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 Warren County, 2008 to 2017, laboratory

Reported results by concentration band, Warren County, 2008 to 2017, laboratory
Under 2 pCi/L: 22%2 to 4 pCi/L: 17%4 pCi/L and above: 61%

Of 1,624 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Warren County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L35021.6%
2 to 4 pCi/L27516.9%
4 pCi/L and above99961.5%
What these figures count

These are the 1,624 tests reported to CDC for Warren 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

Warren County, Compared

Warren County radon figures, compared

Calculated by Radon411

More than half: 61.5% of the 1,624 radon tests reported to CDC for Warren County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 4th of 69 Kentucky counties with 30 or more tests for the same period. That is 17.8 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 583.3 pCi/L. The rest split 21.6% under 2 pCi/L and 16.9% from 2 to 4 (Kentucky: 33.2% and 23.1%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 61.5% 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 Warren County went from 1,349 tests (2005 to 2014) to 1,624 (2008 to 2017), the share going from 65.4% to 61.5%.

Nationally, every county with a figure for the same period pools to 35.7%; Warren County sits 25.8 points above it. CDC also counts 101 tests taken after mitigation in Warren County for the same period: tests in homes where a fix was already in.

Warren County against Kentucky, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Warren County
Warren County1,62461.5%6.3 pCi/LThis county
Kentucky, pooled120 counties, pooled28,79343.7%Not pooled−17.8 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−25.8 points
Meade Countyhighest in the state11768.4%8.2 pCi/L+6.9 points
Hopkins Countylowest in the state429.5%1.7 pCi/L−52.0 points
Barren County, KYborders it18651.6%4.0 pCi/L−9.9 points
Simpson County, KYborders it12632.5%2.6 pCi/L−29.0 points
Logan County, KYborders it7931.6%2.4 pCi/L−29.9 points
Allen County, KYborders it5829.3%1.9 pCi/L−32.2 points
Edmonson County, KYborders it6221.0%1.6 pCi/L−40.5 points
Butler County, KYborders it263.8%1.5 pCi/L−57.7 points
Where Warren County's reported results fell, 2008 to 2017, laboratory, beside Kentucky and the United States
ResultWarren County testsWarren County shareKentucky shareU.S. shareAgainst Kentucky
Under 2 pCi/L35021.6%33.2%39.6%−11.6 points
2 to 4 pCi/L27516.9%23.1%24.7%−6.2 points
4 pCi/L and above99961.5%43.7%35.7%+17.8 points
Warren 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
Warren County ten-year laboratory totals, against Kentucky's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestKentucky, pooledChange from the row before
2008 to 20171,62461.5%6.3 pCi/L583.3 pCi/L43.7%−2.1 points
2007 to 20161,49663.6%6.7 pCi/L583.3 pCi/L45.1%−1.4 points
2006 to 20151,41465.0%7.1 pCi/L583.3 pCi/L46.4%−0.4 points
2005 to 20141,34965.4%7.1 pCi/L583.3 pCi/L47.3%First on file

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

Warren County, Geology

The ground under Warren County

Predicted

Most of the ground under Warren County is one class on USGS's geologic map: 99.9% of its land is moderate radon potential, with 0.1% high. The map puts 93.6% of Warren County in the area it calls Mississippian Plateau and 6.3% in Western Coalfield. USGS gives the first a radon index of 11 and the second 9, both in the moderate band (9 to 11).

USGS's geologic areas under Warren County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Mississippian PlateauMississippian marine limestones, dolomites, marine sandstones, siltstones, and shales.Moderate1193.6%
Western CoalfieldLimestones, shale, siltstone, and coal beds.Moderate96.3%

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

Warren County beside the ground around it

Kentucky as a whole has more high-potential ground than Warren County: 18.2% of its land, against 0.1% here. Of the 6 counties that border it, 2 have more high-potential ground, Allen County the most at 61.5%.

Share of land by USGS radon potential: Warren County, the 6 counties bordering it and Kentucky
AreaEPA zoneLow potentialModerate potentialHigh potential
Warren CountyZone 1None99.9%0.1%
Allen CountyZone 1None38.5%61.5%
Simpson CountyZone 2None100%None
Edmonson CountyZone 2None100%None
Butler CountyZone 2None100%None
Barren CountyZone 1None50.0%50.0%
Logan CountyZone 2None100%None
Kentucky120 counties, pooled by land areaVaries5.7%76.1%18.2%

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

Local help

Warren County, Local resources

Radon testing and mitigation in Warren County

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

What it means

Warren County, Questions

Questions about radon in Warren County

Are radon levels high in Warren County?

Over the 2008 to 2017 laboratory totals, 61.5% of the radon tests reported to CDC for Warren 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, 3 reported a higher share; pooled, the state comes to 43.7%.

Which counties border Warren County?

Warren County borders 6 counties: Allen County, Simpson County, Edmonson County, Butler County, Barren County and Logan County.

Products

Warren County, Products

Testing a home in Warren County

In Warren County, 61.5% of 1,624 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 Warren 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

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

Explore

Warren County, Bordering counties

Counties bordering Warren County

Calculated by Radon411

Warren County, Cities and towns

Cities and towns in Warren County

Warren County is growing: the Census Bureau puts it at 149,375 residents on July 1, 2025, up 10.6% from 135,039 in 2020. That works out to 276 people per square mile of land. Bowling Green alone is home to 78,505 of them, 52.6% of the total. Together its 5 incorporated places hold 53.9% of those residents; the other 46.1% live outside any of them. Testing is reported here more often than across the state: CDC's 1,624 reported tests for 2008 to 2017 come to 10.9 for every 1,000 residents (2025 estimate), against 6.3 for Kentucky.

From Bowling Green to Oakland, CDC publishes no figure by town: each reads Warren County's.

The cities and towns in Warren County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Bowling Green78,505+8.3%52.6%
Smiths Grove852+12.5%0.6%
Plum Springs563+12.4%0.4%
Woodburn340+12.6%0.2%
Oakland193−3.5%0.1%

5 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).

Warren County, Homes

Homes in Warren County

Of Warren County's 58,563 homes, 63% are detached houses, against 68% across Kentucky; 19% are in buildings of five or more homes. Much of Warren County is recent building: 38% of its homes have gone up since 2000 and the middle year built is 1992, against 1982 for Kentucky. 57% 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 Warren County, Kentucky, 2019 to 2023
HomesWarren CountyKentucky
Housing units58,5632,010,655
Detached houses63%68%
In buildings of 5 or more19%12%
Mobile homes6%11%
Built before 196013%22%
Built since 200038%24%
Middle year built19921982
Owner-occupied57%68%

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