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Radon Levels in Franklin County, Indiana

EPA puts Franklin County in Zone 2, its middle radon zone, and 28.0% of its 50 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

    28.0%

    10.9 pts below IN

    Franklin
    28.0%
    Indiana
    38.9%

    50 tests, 2008 to 2017

  • Median result

    2.1pCi/L

    Below action level

    Franklin
    2.1 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    50

    63rd of 69 by tests

    Franklin
    50
    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

    63 of 69

    Lowest quarter

    Franklin
    28.0%
    Miami
    63.3%

    By share, of 69 with 30+ tests

Read a result for Franklin County

Starts at Franklin County's median, 2.1 pCi/L

2.1pCi/L

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

EPA’s reading of 2.1 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. Franklin County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Franklin County, At a glance

Franklin County at a glance

Predicted: EPA radon zone

EPA Zone 2: moderate predicted potential

Franklin 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 63% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, Franklin County, 2008 to 2017, laboratory
Under 2 pCi/L: 50%2 to 4 pCi/L: 22%4 pCi/L and above: 28%

Of 50 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Franklin County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L2550.0%
2 to 4 pCi/L1122.0%
4 pCi/L and above1428.0%
What these figures count

These are the 50 tests reported to CDC for Franklin 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

Franklin County, Compared

Franklin County radon figures, compared

Calculated by Radon411

Franklin County's 50 reported tests over the 2008 to 2017 laboratory totals had a middle value of 2.1 pCi/L and a maximum of 14.4 pCi/L, and 28.0% reached 4 pCi/L. Indiana as a whole (92 Indiana counties, pooled) comes to 38.9%: 10.9 points higher than here.

Among its state's counties it ranks 63rd of 69 Indiana counties with 30 or more tests for the same period. Statewide for the same period, Miami County reported the highest share (63.3%) and Jasper County the lowest (14.1%).

Below the action level, 25 tests (50.0%) came in under 2 pCi/L, against 32.8% statewide, and 11 tests (22.0%) fell between 2 and 4, against 28.3% statewide. CDC's ten-year totals for Franklin County went from 39 tests (2005 to 2014) to 50 (2008 to 2017), the share going from 33.3% to 28.0%.

EPA's 1993 zone map puts Franklin County in Zone 2, a predicted county average between 2 and 4 pCi/L. USGS geology rates 63% of the county's land moderate radon potential.

Next door, the shares run from 30.1% in Dearborn County to 54.3% in Butler County, OH.

CDC also counts 15 tests taken after mitigation in Franklin County for the same period: tests in homes where a fix was already in.

Franklin County against Indiana, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Franklin County
Franklin County5028.0%2.1 pCi/LThis county
Indiana, pooled92 counties, pooled43,14838.9%Not pooled+10.9 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+7.7 points
Miami Countyhighest in the state3063.3%5.3 pCi/L+35.3 points
Jasper Countylowest in the state7114.1%1.2 pCi/L−13.9 points
Fayette County, INborders it1376.9%7.9 pCi/L+48.9 points
Butler County, OHborders it1,95354.3%4.4 pCi/L+26.3 points
Union County, INborders it850.0%3.8 pCi/L+22.0 points
Rush County, INborders it1747.1%3.9 pCi/L+19.1 points
Ripley County, INborders it6835.3%2.9 pCi/L+7.3 points
Hamilton County, OHborders it3,75434.7%2.8 pCi/L+6.7 points
Decatur County, INborders it6333.3%2.8 pCi/L+5.3 points
Dearborn County, INborders it13630.1%2.6 pCi/L+2.1 points
Where Franklin County's reported results fell, 2008 to 2017, laboratory, beside Indiana and the United States
ResultFranklin County testsFranklin County shareIndiana shareU.S. shareAgainst Indiana
Under 2 pCi/L2550.0%32.8%39.6%+17.2 points
2 to 4 pCi/L1122.0%28.3%24.7%−6.3 points
4 pCi/L and above1428.0%38.9%35.7%−10.9 points
Franklin 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
Hancock County58 of 6927133.9%2.6 pCi/L
Decatur County59 of 696333.3%2.8 pCi/L
Greene County60 of 694932.7%3.0 pCi/L
Dearborn County61 of 6913630.1%2.6 pCi/L
St. Joseph County62 of 697,34629.3%2.7 pCi/L
Franklin County63 of 695028.0%2.1 pCi/L
Jackson County64 of 698827.3%2.8 pCi/L
Brown County65 of 6911225.9%2.8 pCi/L
Vanderburgh County66 of 691,50524.4%2.4 pCi/L
Lake County67 of 691,19823.5%1.8 pCi/L
Warrick County68 of 6956120.9%1.8 pCi/L
Franklin County ten-year laboratory totals, against Indiana's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestIndiana, pooledChange from the row before
2008 to 20175028.0%2.1 pCi/L14.4 pCi/L38.9%−9.3 points
2007 to 20165137.3%2.9 pCi/L14.4 pCi/L39.2%+5.4 points
2006 to 20154731.9%2.4 pCi/L14.4 pCi/L39.6%−1.4 points
2005 to 20143933.3%2.6 pCi/L14.4 pCi/L39.3%First on file

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

Franklin County, Geology

The ground under Franklin County

Predicted

USGS's geologic map splits Franklin County: 63.0% of its land is moderate radon potential and 37.0% high. The map puts 63.0% of Franklin County in the area it calls Dearborn Upland and 37.0% in Huron-Erie Lobe. USGS gives the first a radon index of 10, in the moderate band (9 to 11), and the second 13, in the high band (12 to 17).

USGS's geologic areas under Franklin County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Dearborn UplandOrdovician through Devonian limestone, dolostone, and gray shale, and pre-Wisconsinan glacial deposits.Moderate1063.0%
Huron-Erie LobeCalcareous clayey and loamy glacial deposits derived from marine carbonate and clastic sedimentary rocks.High1337.0%

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

Franklin County beside the ground around it

Indiana as a whole has more high-potential ground than Franklin County: 56.6% of its land, against 37.0% here. Of the 8 counties that border it, 5 have more high-potential ground, Union County the most at 100%.

Share of land by USGS radon potential: Franklin County, the 8 counties bordering it and Indiana
AreaEPA zoneLow potentialModerate potentialHigh potential
Franklin CountyZone 2None63.0%37.0%
Dearborn CountyZone 2None100%None
Fayette CountyZone 1None7.1%92.9%
Union CountyZone 1NoneNone100%
Decatur CountyZone 1None33.5%66.5%
Ripley CountyZone 2None100%None
Butler County, OHZone 1None0.2%99.8%
Rush CountyZone 1NoneNone100%
Hamilton County, OHZone 1None88.5%11.5%
Indiana92 counties, pooled by land areaVariesNone43.4%56.6%

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

Local help

Franklin County, Local resources

Radon testing and mitigation in Franklin 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

Franklin County, Questions

Questions about radon in Franklin County

Are radon levels high in Franklin County?

Over the 2008 to 2017 laboratory totals, 28.0% of the radon tests reported to CDC for Franklin County, Indiana were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.1 pCi/L. Of 69 Indiana counties with 30 or more tests for the same period, 62 reported a higher share; pooled, the state comes to 38.9%.

Which counties border Franklin County?

Franklin County borders 8 counties: Dearborn County, IN, Fayette County, IN, Union County, IN, Decatur County, IN, Ripley County, IN, Butler County, OH, Rush County, IN and Hamilton County, OH.

Products

Franklin County, Products

Testing a home in Franklin County

In Franklin County, 28.0% of 50 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 Franklin County; a long-term test tells the year-round average.

Test kits and monitors3

See every kit and monitor

Best radon monitors for Franklin County homes, compared

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Franklin County, Bordering counties

Counties bordering Franklin County

Calculated by Radon411

Franklin County, Cities and towns

Cities and towns in Franklin County

The Census Bureau estimates 23,286 residents in Franklin County for July 1, 2025, 495 more than in 2020 (+2.2%). That works out to 61 people per square mile of land. Batesville, the largest place on its list (7,401 residents in all), extends beyond Franklin County, so no share of the total is worked out for it. Reported testing is thin here: 50 tests over 2008 to 2017, or 2.1 for every 1,000 residents (2025 estimate), where Indiana as a whole comes to 6.2.

From Batesville to Mount Carmel, CDC publishes no figure by town: each reads Franklin County's.

The cities and towns in Franklin County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Batesvilleextends beyond Franklin County7,401+2.7%Counted whole
Brookville2,663+1.7%11.4%
Oldenburg651+1.2%2.8%
Laurel414+1.5%1.8%
Cedar Grove148+0.7%0.6%
Mount Carmel90+3.4%0.4%

6 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). A place that extends beyond Franklin County is counted whole, so it has no share.

Franklin County, Homes

Homes in Franklin County

Franklin County is a place of houses on their own lots: 79% of its 9,749 homes are detached single-family houses, against 73% across Indiana. Half of its homes were built before 1983, close to Indiana's 1976: 25% date from before 1960 and 22% from 2000 or later. Owners live in 81% of the occupied homes (Indiana: 70%), so for most households a test and a fix are their own to order.

Homes in Franklin County, Indiana, 2019 to 2023
HomesFranklin CountyIndiana
Housing units9,7492,953,344
Detached houses79%73%
In buildings of 5 or more3%13%
Mobile homes13%4%
Built before 196025%32%
Built since 200022%21%
Middle year built19831976
Owner-occupied81%70%

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