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Radon Levels in Allen County, Kentucky

EPA puts Allen County in Zone 1, its highest radon zone, and 29.3% of its 58 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

    29.3%

    14.4 pts below KY

    Allen
    29.3%
    Kentucky
    43.7%

    58 tests, 2008 to 2017

  • Median result

    1.9pCi/L

    Below action level

    Allen
    1.9 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    58

    50th of 69 by tests

    Allen
    58
    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

    46 of 69

    Middle half

    Allen
    29.3%
    Meade
    68.4%

    By share, of 69 with 30+ tests

Read a result for Allen County

Starts at Allen County's median, 1.9 pCi/L

1.9pCi/L

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

EPA’s reading of 1.9 pCi/L

Below 2 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 below 2 pCi/L, the level at which EPA says a fix should be considered. Allen County's median reported result, 2008 to 2017.

Interpret this reading

The data

Allen County, At a glance

Allen County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Allen 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 61% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, Allen County, 2008 to 2017, laboratory
Under 2 pCi/L: 50%2 to 4 pCi/L: 21%4 pCi/L and above: 29%

Of 58 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Allen County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L2950.0%
2 to 4 pCi/L1220.7%
4 pCi/L and above1729.3%
What these figures count

These are the 58 tests reported to CDC for Allen 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

Allen County, Compared

Allen County radon figures, compared

Calculated by Radon411

Allen County's 58 reported tests over the 2008 to 2017 laboratory totals had a middle value of 1.9 pCi/L and a maximum of 32.2 pCi/L, and 29.3% reached 4 pCi/L. Kentucky as a whole (120 Kentucky counties, pooled) comes to 43.7%: 14.4 points higher than here.

Among its state's counties it ranks 46th of 69 Kentucky counties with 30 or more tests for the same period. Statewide for the same period, Meade County reported the highest share (68.4%) and Hopkins County the lowest (9.5%).

Below the action level, 29 tests (50.0%) came in under 2 pCi/L, against 33.2% statewide, and 12 tests (20.7%) fell between 2 and 4, against 23.1% statewide. CDC's ten-year totals for Allen County went from 40 tests (2005 to 2014) to 58 (2008 to 2017), the share going from 27.5% to 29.3%.

EPA's 1993 zone map puts Allen County in Zone 1, a predicted county average above 4 pCi/L. USGS geology rates 61% of the county's land high radon potential.

Next door, the shares run from 19.4% in Macon County, TN to 61.5% in Warren County, with Sumner County, TN and Macon County, TN below Allen County.

Allen County against Kentucky, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Allen County
Allen County5829.3%1.9 pCi/LThis county
Kentucky, pooled120 counties, pooled28,79343.7%Not pooled+14.4 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+6.4 points
Meade Countyhighest in the state11768.4%8.2 pCi/L+39.1 points
Hopkins Countylowest in the state429.5%1.7 pCi/L−19.8 points
Warren County, KYborders it1,62461.5%6.3 pCi/L+32.2 points
Monroe County, KYborders it8752.9%4.6 pCi/L+23.6 points
Barren County, KYborders it18651.6%4.0 pCi/L+22.3 points
Simpson County, KYborders it12632.5%2.6 pCi/L+3.2 points
Sumner County, TNborders it1,31126.0%1.9 pCi/L−3.3 points
Macon County, TNborders it6719.4%1.9 pCi/L−9.9 points
Where Allen County's reported results fell, 2008 to 2017, laboratory, beside Kentucky and the United States
ResultAllen County testsAllen County shareKentucky shareU.S. shareAgainst Kentucky
Under 2 pCi/L2950.0%33.2%39.6%+16.8 points
2 to 4 pCi/L1220.7%23.1%24.7%−2.4 points
4 pCi/L and above1729.3%43.7%35.7%−14.4 points
Allen 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
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
Spencer County44 of 6916631.3%2.5 pCi/L
Breckinridge County45 of 693231.3%2.5 pCi/L
Allen County46 of 695829.3%1.9 pCi/L
Clark County47 of 6923129.0%2.4 pCi/L
Grayson County48 of 693627.8%2.2 pCi/L
Washington County49 of 694427.3%2.4 pCi/L
Pendleton County50 of 693426.5%1.9 pCi/L
Campbell County51 of 6954326.2%2.3 pCi/L
Allen County ten-year laboratory totals, against Kentucky's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestKentucky, pooledChange from the row before
2008 to 20175829.3%1.9 pCi/L32.2 pCi/L43.7%−1.1 points
2007 to 20165630.4%1.9 pCi/L32.2 pCi/L45.1%−1.7 points
2006 to 20155332.1%2.0 pCi/L32.2 pCi/L46.4%+4.6 points
2005 to 20144027.5%1.9 pCi/L32.2 pCi/L47.3%First on file

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

Allen County, Geology

The ground under Allen County

Predicted

USGS's geologic map splits Allen County: 61.5% of its land is high radon potential and 38.5% moderate. The map puts 60.9% of Allen County in the area it calls Eastern Pennyroyal and 38.5% in Mississippian Plateau, with one smaller area beside them. USGS gives the first a radon index of 12, in the high band (12 to 17), and the second 11, in the moderate band (9 to 11).

USGS's geologic areas under Allen County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Eastern PennyroyalMarine shale, sandstone and limestone.High1260.9%
Mississippian PlateauMississippian marine limestones, dolomites, marine sandstones, siltstones, and shales.Moderate1138.5%
Cherty HighlandCherty dolostone.High120.5%

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

Allen County beside the ground around it

Allen County has more high-potential ground than Kentucky as a whole: 61.5% of its land against 18.2%. Of the 6 counties that border it, 3 have more high-potential ground, Macon County, TN the most at 100%.

Share of land by USGS radon potential: Allen County, the 6 counties bordering it and Kentucky
AreaEPA zoneLow potentialModerate potentialHigh potential
Allen CountyZone 1None38.5%61.5%
Warren CountyZone 1None99.9%0.1%
Macon County, TNZone 1NoneNone100%
Simpson CountyZone 2None100%None
Barren CountyZone 1None50.0%50.0%
Monroe CountyZone 1NoneNone100%
Sumner County, TNZone 2None20.4%79.6%
Kentucky120 counties, pooled by land areaVaries5.7%76.1%18.2%

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

Local help

Allen County, Local resources

Radon testing and mitigation in Allen County

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

What it means

Allen County, Questions

Questions about radon in Allen County

Are radon levels high in Allen County?

Over the 2008 to 2017 laboratory totals, 29.3% of the radon tests reported to CDC for Allen County, Kentucky were at or above 4 pCi/L, and the median reported pre-mitigation result was 1.9 pCi/L. Of 69 Kentucky counties with 30 or more tests for the same period, 45 reported a higher share; pooled, the state comes to 43.7%.

Which counties border Allen County?

Allen County borders 6 counties: Warren County, KY, Macon County, TN, Simpson County, KY, Barren County, KY, Monroe County, KY and Sumner County, TN.

Products

Allen County, Products

Testing a home in Allen County

In Allen County, 29.3% of 58 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 Allen 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

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

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Allen County, Bordering counties

Counties bordering Allen County

Calculated by Radon411

Allen County, Cities and towns

Cities and towns in Allen County

Allen County is growing: the Census Bureau puts it at 22,536 residents on July 1, 2025, up 9.5% from 20,573 in 2020. That works out to 65 people per square mile of land. Scottsville, its one incorporated place, has 4,673 residents, 20.7% of the total. Reported testing is thin here: 58 tests over 2008 to 2017, or 2.6 for every 1,000 residents (2025 estimate), where Kentucky as a whole comes to 6.3.

Scottsville is the one incorporated place here; CDC publishes no figure by town, so it reads Allen County's.

Scottsville, Allen County: residents on July 1, 2025
PlaceResidentsSince 2020Share of residents
Scottsville4,673+9.3%20.7%

One incorporated place, 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).

Allen County, Homes

Homes in Allen County

Of Allen County's 9,261 homes, 74% are detached houses, against 68% across Kentucky; 19% are mobile homes. Half of its homes were built before 1988, close to Kentucky's 1982: 19% date from before 1960 and 31% from 2000 or later. 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 Allen County, Kentucky, 2019 to 2023
HomesAllen CountyKentucky
Housing units9,2612,010,655
Detached houses74%68%
In buildings of 5 or more4%12%
Mobile homes19%11%
Built before 196019%22%
Built since 200031%24%
Middle year built19881982
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.