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Radon Levels in Harrison County, Kentucky

EPA puts Harrison County in Zone 1, its highest radon zone, and high results are common there: 46.8% of the 111 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

    46.8%

    3.1 pts above KY

    Harrison
    46.8%
    Kentucky
    43.7%

    111 tests, 2008 to 2017

  • Median result

    3.4pCi/L

    Below action level

    Harrison
    3.4 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    111

    33rd of 69 by tests

    Harrison
    111
    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

    22 of 69

    Middle half

    Harrison
    46.8%
    Meade
    68.4%

    By share, of 69 with 30+ tests

Read a result for Harrison County

Starts at Harrison County's median, 3.4 pCi/L

3.4pCi/L

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

EPA’s reading of 3.4 pCi/L

Between 2 and 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 between 2 and 4 pCi/L. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. Harrison County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Harrison County, At a glance

Harrison County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Harrison 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 65% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, Harrison County, 2008 to 2017, laboratory
Under 2 pCi/L: 36%2 to 4 pCi/L: 17%4 pCi/L and above: 47%

Of 111 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Harrison County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L4036.0%
2 to 4 pCi/L1917.1%
4 pCi/L and above5246.8%
What these figures count

These are the 111 tests reported to CDC for Harrison 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

Harrison County, Compared

Harrison County radon figures, compared

Calculated by Radon411

In Harrison County, about 5 in 10 reported tests over the 2008 to 2017 laboratory totals (52 of 111) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 11.1 points higher. Across 120 Kentucky counties pooled together, 43.7% of tests reached that level, so Harrison County runs 3.1 points above its state.

Of 4 neighbours with a figure, 2 reported a larger share at or above 4 pCi/L and 2 a smaller one; the spread is 26.5% (Pendleton County) to 53.5% (Bourbon County). By share, Harrison County is 22nd of 69 Kentucky counties with 30 or more tests for the same period.

Half the tests came in under 3.4 pCi/L and half over it; the single highest reached 28.0 pCi/L. Below the action level, 40 tests (36.0%) came in under 2 pCi/L, against 33.2% statewide, and 19 tests (17.1%) fell between 2 and 4, against 23.1% statewide.

Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 46.8% share point the same way here. USGS geology rates 65% of the county's land moderate radon potential.

CDC's ten-year totals for Harrison County went from 77 tests (2005 to 2014) to 111 (2008 to 2017), the share going from 40.3% to 46.8%.

Harrison County against Kentucky, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Harrison County
Harrison County11146.8%3.4 pCi/LThis county
Kentucky, pooled120 counties, pooled28,79343.7%Not pooled−3.1 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−11.1 points
Meade Countyhighest in the state11768.4%8.2 pCi/L+21.6 points
Hopkins Countylowest in the state429.5%1.7 pCi/L−37.3 points
Bourbon County, KYborders it12753.5%4.8 pCi/L+6.7 points
Scott County, KYborders it87546.9%3.6 pCi/L+0.1 points
Grant County, KYborders it7833.3%2.5 pCi/L−13.5 points
Pendleton County, KYborders it3426.5%1.9 pCi/L−20.3 points
Robertson County, KYborders it425.0%1.1 pCi/L−21.8 points
Bracken County, KYborders it520.0%2.0 pCi/L−26.8 points
Nicholas County, KYborders it2010.0%1.9 pCi/L−36.8 points
Where Harrison County's reported results fell, 2008 to 2017, laboratory, beside Kentucky and the United States
ResultHarrison County testsHarrison County shareKentucky shareU.S. shareAgainst Kentucky
Under 2 pCi/L4036.0%33.2%39.6%+2.8 points
2 to 4 pCi/L1917.1%23.1%24.7%−6.0 points
4 pCi/L and above5246.8%43.7%35.7%+3.1 points
Harrison 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
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
Harrison County22 of 6911146.8%3.4 pCi/L
Metcalfe County23 of 693345.5%3.5 pCi/L
Estill County24 of 6917744.1%3.2 pCi/L
Adair County25 of 695343.4%3.8 pCi/L
Franklin County26 of 6981043.1%3.3 pCi/L
Boone County27 of 691,43442.9%3.5 pCi/L
Harrison County ten-year laboratory totals, against Kentucky's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestKentucky, pooledChange from the row before
2008 to 201711146.8%3.4 pCi/L28.0 pCi/L43.7%+4.6 points
2007 to 201610242.2%2.6 pCi/L28.0 pCi/L45.1%+5.0 points
2006 to 20159437.2%2.4 pCi/L21.0 pCi/L46.4%−3.1 points
2005 to 20147740.3%2.5 pCi/L16.1 pCi/L47.3%First on file

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

Harrison County, Geology

The ground under Harrison County

Predicted

USGS's geologic map splits Harrison County: 65.3% of its land is moderate radon potential and 34.7% high. The map puts 65.3% of Harrison County in the area it calls Outer Bluegrass and 34.7% in Inner Bluegrass. USGS gives the first a radon index of 11, in the moderate band (9 to 11), and the second 13, in the high band (12 to 17).

USGS's geologic areas under Harrison County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Outer BluegrassOrdovician-Devonian limestone and shale.Moderate1165.3%
Inner BluegrassOrdovician limestones, dolomites and shales.High1334.7%

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

Harrison County beside the ground around it

Harrison County has more high-potential ground than Kentucky as a whole: 34.7% of its land against 18.2%. Of the 7 counties that border it, 3 have more high-potential ground, Scott County the most at 50.7%.

Share of land by USGS radon potential: Harrison County, the 7 counties bordering it and Kentucky
AreaEPA zoneLow potentialModerate potentialHigh potential
Harrison CountyZone 1None65.3%34.7%
Bourbon CountyZone 1None55.9%44.1%
Scott CountyZone 1None49.3%50.7%
Robertson CountyZone 1None86.9%13.1%
Nicholas CountyZone 2None97.3%2.7%
Pendleton CountyZone 1None60.2%39.8%
Bracken CountyZone 2None99.1%0.9%
Grant 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

Harrison County, Local resources

Radon testing and mitigation in Harrison County

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

What it means

Harrison County, Questions

Questions about radon in Harrison County

Are radon levels high in Harrison County?

Over the 2008 to 2017 laboratory totals, 46.8% of the radon tests reported to CDC for Harrison County, Kentucky were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.4 pCi/L. Of 69 Kentucky counties with 30 or more tests for the same period, 21 reported a higher share; pooled, the state comes to 43.7%.

Which counties border Harrison County?

Harrison County borders 7 counties: Bourbon County, Scott County, Robertson County, Nicholas County, Pendleton County, Bracken County and Grant County.

Products

Harrison County, Products

Testing a home in Harrison County

In Harrison County, 46.8% of 111 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 Harrison 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

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

Explore

Harrison County, Bordering counties

Counties bordering Harrison County

Calculated by Radon411

Harrison County, Cities and towns

Cities and towns in Harrison County

The Census Bureau estimates 19,627 residents in Harrison County for July 1, 2025, 917 more than in 2020 (+4.9%). That works out to 64 people per square mile of land. Its largest town, Cynthiana, has 6,576 residents, 33.5% of the total. Together its 2 incorporated places hold 34.8% of those residents; the other 65.2% live outside any of them. CDC's 111 reported tests for 2008 to 2017 work out to 5.7 per 1,000 residents (2025 estimate), close to Kentucky's 6.3.

From Cynthiana to Berry, CDC publishes no figure by town: each reads Harrison County's.

The cities and towns in Harrison County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Cynthiana6,576+3.7%33.5%
Berry262+3.6%1.3%

2 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).

Harrison County, Homes

Homes in Harrison County

Of Harrison County's 8,136 homes, 74% are detached houses, against 68% across Kentucky; 12% are mobile homes. Half of its homes were built before 1979, close to Kentucky's 1982: 29% date from before 1960 and 19% from 2000 or later. 70% 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 Harrison County, Kentucky, 2019 to 2023
HomesHarrison CountyKentucky
Housing units8,1362,010,655
Detached houses74%68%
In buildings of 5 or more5%12%
Mobile homes12%11%
Built before 196029%22%
Built since 200019%24%
Middle year built19791982
Owner-occupied70%68%

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