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Radon Levels in Jefferson County, Indiana

EPA puts Jefferson County in Zone 2, its middle radon zone, and high results are common there: 45.8% of the 72 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

    45.8%

    6.9 pts above IN

    Jefferson
    45.8%
    Indiana
    38.9%

    72 tests, 2008 to 2017

  • Median result

    3.1pCi/L

    Below action level

    Jefferson
    3.1 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    72

    53rd of 69 by tests

    Jefferson
    72
    St. Joseph
    7,346

    Reported to CDC before any fix, 2008 to 2017

  • EPA radon zone

    Zone 2

    Moderate potential

    1. 1
    2. Zone 2
    3. 3

    1 highest, 3 lowest

    EPA predicts 2 to 4 pCi/L indoors

  • Rank in Indiana

    29 of 69

    Middle half

    Jefferson
    45.8%
    Miami
    63.3%

    By share, of 69 with 30+ tests

Read a result for Jefferson County

Starts at Jefferson County's median, 3.1 pCi/L

3.1pCi/L

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

EPA’s reading of 3.1 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. Jefferson County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Jefferson County, At a glance

Jefferson County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Jefferson County is a county: EPA's forecast for it as a whole is an average indoor of 2 to 4 pCi/L (75 to 150 Bq/m³). It describes no single address, and homes above EPA's are found in every zone, this one included.

USGS geologic potential: Moderate across 76% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, Jefferson County, 2008 to 2017, laboratory
Under 2 pCi/L: 37%2 to 4 pCi/L: 17%4 pCi/L and above: 46%

Of 72 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Jefferson County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L2737.5%
2 to 4 pCi/L1216.7%
4 pCi/L and above3345.8%
What these figures count

These are the 72 tests reported to CDC for Jefferson 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

Jefferson County, Compared

Jefferson County radon figures, compared

Calculated by Radon411

In Jefferson County, about 5 in 10 reported tests over the 2008 to 2017 laboratory totals (33 of 72) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 10.1 points higher. Across 92 Indiana counties pooled together, 38.9% of tests reached that level, so Jefferson County runs 6.9 points above its state.

Of 3 neighbours with a figure, 1 reported a larger share at or above 4 pCi/L and 2 a smaller one; the spread is 35.1% (Jennings County) to 47.7% (Clark County). By share, Jefferson County is 29th of 69 Indiana counties with 30 or more tests for the same period.

Half the tests came in under 3.1 pCi/L and half over it; the single highest reached 30.5 pCi/L. Below the action level, 27 tests (37.5%) came in under 2 pCi/L, against 32.8% statewide, and 12 tests (16.7%) fell between 2 and 4, against 28.3% statewide.

Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 45.8% share point the same way here. USGS geology rates 76% of the county's land moderate radon potential. CDC also counts 15 tests taken after mitigation in Jefferson County for the same period: tests in homes where a fix was already in.

CDC's ten-year totals for Jefferson County went from 67 tests (2005 to 2014) to 72 (2008 to 2017), the share going from 50.7% to 45.8%.

Jefferson County against Indiana, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Jefferson County
Jefferson County7245.8%3.1 pCi/LThis county
Indiana, pooled92 counties, pooled43,14838.9%Not pooled−6.9 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−10.1 points
Miami Countyhighest in the state3063.3%5.3 pCi/L+17.5 points
Jasper Countylowest in the state7114.1%1.2 pCi/L−31.7 points
Clark County, INborders it51247.7%3.6 pCi/L+1.9 points
Trimble County, KYborders it2445.8%3.7 pCi/LLevel
Carroll County, KYborders it2638.5%3.5 pCi/L−7.3 points
Scott County, INborders it1735.3%2.0 pCi/L−10.5 points
Ripley County, INborders it6835.3%2.9 pCi/L−10.5 points
Jennings County, INborders it5735.1%2.8 pCi/L−10.7 points
Switzerland County, INborders it1533.3%1.5 pCi/L−12.5 points
Where Jefferson County's reported results fell, 2008 to 2017, laboratory, beside Indiana and the United States
ResultJefferson County testsJefferson County shareIndiana shareU.S. shareAgainst Indiana
Under 2 pCi/L2737.5%32.8%39.6%+4.7 points
2 to 4 pCi/L1216.7%28.3%24.7%−11.6 points
4 pCi/L and above3345.8%38.9%35.7%+6.9 points
Jefferson County ranked among the 69 Indiana counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Clark County24 of 6951247.7%3.6 pCi/L
Porter County25 of 691,13646.5%3.5 pCi/L
Fulton County26 of 699746.4%3.3 pCi/L
Elkhart County27 of 692,85646.4%3.7 pCi/L
Clinton County28 of 698545.9%3.5 pCi/L
Jefferson County29 of 697245.8%3.1 pCi/L
Morgan County30 of 6922644.2%3.5 pCi/L
Dubois County31 of 6913644.1%3.7 pCi/L
Vigo County32 of 6945544.0%3.6 pCi/L
Huntington County33 of 6916943.8%3.5 pCi/L
Gibson County34 of 6912043.3%3.4 pCi/L
Jefferson County ten-year laboratory totals, against Indiana's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestIndiana, pooledChange from the row before
2008 to 20177245.8%3.1 pCi/L30.5 pCi/L38.9%−2.3 points
2007 to 20167748.1%3.3 pCi/L30.5 pCi/L39.2%−1.3 points
2006 to 20157949.4%3.5 pCi/L30.5 pCi/L39.6%−1.3 points
2005 to 20146750.7%4.4 pCi/L30.5 pCi/L39.3%First on file

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

Jefferson County, Geology

The ground under Jefferson County

Predicted

Most of the ground under Jefferson County is one class on USGS's geologic map: 76.2% of its land is moderate radon potential, with 23.8% high. The map puts 76.2% of Jefferson County in the area it calls Dearborn Upland and 23.8% in New Albany Shale. USGS gives the first a radon index of 10, in the moderate band (9 to 11), and the second 12, in the high band (12 to 17).

USGS's geologic areas under Jefferson County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Dearborn UplandOrdovician through Devonian limestone, dolostone, and gray shale, and pre-Wisconsinan glacial deposits.Moderate1076.2%
New Albany ShaleNew Albany black shale.High1223.8%

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

Jefferson County beside the ground around it

Indiana as a whole has more high-potential ground than Jefferson County: 56.6% of its land, against 23.8% here. Of the 7 counties that border it, 3 have more high-potential ground, Scott County the most at 61.6%.

Share of land by USGS radon potential: Jefferson County, the 7 counties bordering it and Indiana
AreaEPA zoneLow potentialModerate potentialHigh potential
Jefferson CountyZone 2None76.2%23.8%
Trimble County, KYZone 2None100%None
Scott CountyZone 1None38.4%61.6%
Jennings CountyZone 1None44.3%55.7%
Carroll County, KYZone 2None100%None
Ripley CountyZone 2None100%None
Switzerland CountyZone 2None100%None
Clark CountyZone 1None49.1%50.9%
Indiana92 counties, pooled by land areaVariesNone43.4%56.6%

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

Local help

Jefferson County, Local resources

Radon testing and mitigation in Jefferson County

What Indiana's program says
Phone
1-800-272-9723
Licensing of radon professionals
According to the Indiana Radon Rule, 410 IAC 5.1, everyone who is serving Indiana by doing radon testing, analysis and mitigation (radon reduction) in residential structures must be certified by the Indiana State Department of Health.

What it means

Jefferson County, Questions

Questions about radon in Jefferson County

Are radon levels high in Jefferson County?

Over the 2008 to 2017 laboratory totals, 45.8% of the radon tests reported to CDC for Jefferson County, Indiana were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.1 pCi/L. Of 69 Indiana counties with 30 or more tests for the same period, 28 reported a higher share; pooled, the state comes to 38.9%.

Which counties border Jefferson County?

Jefferson County borders 7 counties: Trimble County, KY, Scott County, IN, Jennings County, IN, Carroll County, KY, Ripley County, IN, Switzerland County, IN and Clark County, IN.

Products

Jefferson County, Products

Testing a home in Jefferson County

In Jefferson County, 45.8% of 72 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 38.9% pooled across Indiana. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Jefferson County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Jefferson County homes, compared

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Jefferson County, Bordering counties

Counties bordering Jefferson County

Calculated by Radon411

Jefferson County, Cities and towns

Cities and towns in Jefferson County

The Census Bureau estimates 33,279 residents in Jefferson County for July 1, 2025, 188 more than in 2020 (+0.6%). That works out to 92 people per square mile of land. Its largest town, Madison, has 12,304 residents, 37.0% of the total. Together its 4 incorporated places hold 49.8% of those residents; the other 50.2% live outside any of them. Reported testing is thin here: 72 tests over 2008 to 2017, or 2.2 for every 1,000 residents (2025 estimate), where Indiana as a whole comes to 6.2.

From Madison to Brooksburg, CDC publishes no figure by town: each reads Jefferson County's.

The cities and towns in Jefferson County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Madison12,304−0.2%37.0%
Hanover3,866+3.4%11.6%
Dupont340+0.3%1.0%
Brooksburg71−1.4%0.2%

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).

Jefferson County, Homes

Homes in Jefferson County

Of Jefferson County's 14,446 homes, 71% are detached houses, against 73% across Indiana; 12% are mobile homes. Half of its homes were built before 1972, close to Indiana's 1976: 32% date from before 1960 and 14% from 2000 or later. 69% of occupied homes are lived in by their owner (Indiana: 70%); in the rest a tenant can run a test, but a fix is the landlord's to make.

Homes in Jefferson County, Indiana, 2019 to 2023
HomesJefferson CountyIndiana
Housing units14,4462,953,344
Detached houses71%73%
In buildings of 5 or more6%13%
Mobile homes12%4%
Built before 196032%32%
Built since 200014%21%
Middle year built19721976
Owner-occupied69%70%

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