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Radon Levels in Putnam County, Indiana

EPA puts Putnam County in Zone 1, its highest radon zone, and 34.5% of its 119 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

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    34.5%

    4.4 pts below IN

    Putnam
    34.5%
    Indiana
    38.9%

    119 tests, 2008 to 2017

  • Median result

    2.7pCi/L

    Below action level

    Putnam
    2.7 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    119

    42nd of 69 by tests

    Putnam
    119
    St. Joseph
    7,346

    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 Indiana

    55 of 69

    Lowest quarter

    Putnam
    34.5%
    Miami
    63.3%

    By share, of 69 with 30+ tests

Read a result for Putnam County

Starts at Putnam County's median, 2.7 pCi/L

2.7pCi/L

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

EPA’s reading of 2.7 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. Putnam County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Putnam County, At a glance

Putnam County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Putnam 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 70% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, Putnam County, 2008 to 2017, laboratory
Under 2 pCi/L: 37%2 to 4 pCi/L: 29%4 pCi/L and above: 34%

Of 119 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Putnam County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L4437.0%
2 to 4 pCi/L3428.6%
4 pCi/L and above4134.5%
What these figures count

These are the 119 tests reported to CDC for Putnam 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

Putnam County, Compared

Putnam County radon figures, compared

Calculated by Radon411

In Putnam County, about 3 in 10 reported tests over the 2008 to 2017 laboratory totals (41 of 119) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 1.2 points lower. Across 92 Indiana counties pooled together, 38.9% of tests reached that level, so Putnam County runs 4.4 points below its state.

Of 4 neighbours with a figure, all 4 reported a larger share at or above 4 pCi/L; the spread is 39.1% (Owen County) to 44.2% (Morgan County). By share, Putnam County is 55th of 69 Indiana counties with 30 or more tests for the same period.

Half the tests came in under 2.7 pCi/L and half over it; the single highest reached 45.6 pCi/L. Below the action level, 44 tests (37.0%) came in under 2 pCi/L, against 32.8% statewide, and 34 tests (28.6%) fell between 2 and 4, against 28.3% statewide.

Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 34.5% share point the same way here. USGS geology rates 70% of the county's land high radon potential. CDC also counts 5 tests taken after mitigation in Putnam County for the same period: tests in homes where a fix was already in.

CDC's ten-year totals for Putnam County went from 134 tests (2005 to 2014) to 119 (2008 to 2017), the share going from 43.3% to 34.5%.

Putnam County against Indiana, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Putnam County
Putnam County11934.5%2.7 pCi/LThis county
Indiana, pooled92 counties, pooled43,14838.9%Not pooled+4.4 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+1.2 points
Miami Countyhighest in the state3063.3%5.3 pCi/L+28.8 points
Jasper Countylowest in the state7114.1%1.2 pCi/L−20.4 points
Parke County, INborders it2568.0%4.8 pCi/L+33.5 points
Morgan County, INborders it22644.2%3.5 pCi/L+9.7 points
Hendricks County, INborders it1,17041.5%3.2 pCi/L+7.0 points
Montgomery County, INborders it15241.4%2.9 pCi/L+6.9 points
Owen County, INborders it11039.1%2.8 pCi/L+4.6 points
Clay County, INborders it2326.1%2.9 pCi/L−8.4 points
Where Putnam County's reported results fell, 2008 to 2017, laboratory, beside Indiana and the United States
ResultPutnam County testsPutnam County shareIndiana shareU.S. shareAgainst Indiana
Under 2 pCi/L4437.0%32.8%39.6%+4.2 points
2 to 4 pCi/L3428.6%28.3%24.7%+0.3 points
4 pCi/L and above4134.5%38.9%35.7%−4.4 points
Putnam 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
Lawrence County50 of 6926735.6%2.7 pCi/L
Posey County51 of 6921535.3%2.8 pCi/L
Ripley County52 of 696835.3%2.9 pCi/L
Jennings County53 of 695735.1%2.8 pCi/L
Daviess County54 of 695834.5%3.1 pCi/L
Putnam County55 of 6911934.5%2.7 pCi/L
Monroe County56 of 692,37534.2%2.8 pCi/L
Cass County57 of 699134.1%2.6 pCi/L
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
Putnam County ten-year laboratory totals, against Indiana's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestIndiana, pooledChange from the row before
2008 to 201711934.5%2.7 pCi/L45.6 pCi/L38.9%−5.3 points
2007 to 201612339.8%3.2 pCi/L45.6 pCi/L39.2%−2.0 points
2006 to 201513441.8%3.3 pCi/L45.6 pCi/L39.6%−1.5 points
2005 to 201413443.3%3.3 pCi/L45.6 pCi/L39.3%First on file

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

Putnam County, Geology

The ground under Putnam County

Predicted

USGS's geologic map splits Putnam County: 70.0% of its land is high radon potential and 30.0% moderate. The map puts 70.0% of Putnam County in the area it calls Huron-Erie Lobe and 20.0% in Crawford Upland/Mitchell Plain/Norman Upland, with one smaller area beside them. USGS gives the first a radon index of 13, in the high band (12 to 17), and the second 11, in the moderate band (9 to 11).

USGS's geologic areas under Putnam County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Huron-Erie LobeCalcareous clayey and loamy glacial deposits derived from marine carbonate and clastic sedimentary rocks.High1370.0%
Crawford Upland/Mitchell Plain/Norman UplandUnglaciated, underlain by karsted Mississippian carbonate rocks.Moderate1120.0%
Wabash LowlandLoess, pre-Wisconsinan glacial deposits, Pennsylvanian shale, sandstone, and carbonate bedrock.Moderate1010.0%

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

Putnam County beside the ground around it

Putnam County has more high-potential ground than Indiana as a whole: 70.0% of its land against 56.6%. Of the 6 counties that border it, 2 have more high-potential ground, Hendricks County the most at 100%.

Share of land by USGS radon potential: Putnam County, the 6 counties bordering it and Indiana
AreaEPA zoneLow potentialModerate potentialHigh potential
Putnam CountyZone 1None30.0%70.0%
Parke CountyZone 2None72.8%27.2%
Hendricks CountyZone 1NoneNone100%
Montgomery CountyZone 1None5.9%94.1%
Morgan CountyZone 2None44.4%55.6%
Clay CountyZone 2None100%None
Owen CountyZone 2None100%None
Indiana92 counties, pooled by land areaVariesNone43.4%56.6%

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

Local help

Putnam County, Local resources

Radon testing and mitigation in Putnam 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

Putnam County, Questions

Questions about radon in Putnam County

Are radon levels high in Putnam County?

Over the 2008 to 2017 laboratory totals, 34.5% of the radon tests reported to CDC for Putnam County, Indiana were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.7 pCi/L. Of 69 Indiana counties with 30 or more tests for the same period, 54 reported a higher share; pooled, the state comes to 38.9%.

Which counties border Putnam County?

Putnam County borders 6 counties: Parke County, Hendricks County, Montgomery County, Morgan County, Clay County and Owen County.

Products

Putnam County, Products

Testing a home in Putnam County

In Putnam County, 34.5% of 119 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 38.9% pooled across Indiana. In Zone 1 the year-round level in Putnam 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

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

Explore

Putnam County, Bordering counties

Counties bordering Putnam County

Calculated by Radon411

Putnam County, Cities and towns

Cities and towns in Putnam County

The Census Bureau estimates 37,876 residents in Putnam County for July 1, 2025, 1,180 more than in 2020 (+3.2%). That works out to 79 people per square mile of land. Its largest town, Greencastle, has 9,924 residents, 26.2% of the total. Together its 6 incorporated places hold 38.4% of those residents; the other 61.6% live outside any of them. Reported testing is thin here: 119 tests over 2008 to 2017, or 3.1 for every 1,000 residents (2025 estimate), where Indiana as a whole comes to 6.2.

From Greencastle to Russellville, CDC publishes no figure by town: each reads Putnam County's.

The cities and towns in Putnam County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Greencastle9,924+1.0%26.2%
Cloverdale2,174+5.9%5.7%
Roachdale865+4.0%2.3%
Bainbridge707+4.1%1.9%
Fillmore553+3.6%1.5%
Russellville313+3.6%0.8%

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).

Putnam County, Homes

Homes in Putnam County

Putnam County is a place of houses on their own lots: 80% of its 15,148 homes are detached single-family houses, against 73% across Indiana. Half of its homes were built before 1979, close to Indiana's 1976: 28% date from before 1960 and 18% from 2000 or later. 74% 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 Putnam County, Indiana, 2019 to 2023
HomesPutnam CountyIndiana
Housing units15,1482,953,344
Detached houses80%73%
In buildings of 5 or more6%13%
Mobile homes7%4%
Built before 196028%32%
Built since 200018%21%
Middle year built19791976
Owner-occupied74%70%

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