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Radon Levels in DeKalb County, Indiana

EPA puts DeKalb County in Zone 1, its highest radon zone, and high results are common there: 56.6% of the 242 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

    56.6%

    17.7 pts above IN

    DeKalb
    56.6%
    Indiana
    38.9%

    242 tests, 2008 to 2017

  • Median result

    4.4pCi/L

    Action level reached

    DeKalb
    4.4 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    242

    24th of 69 by tests

    DeKalb
    242
    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

    8 of 69

    Top quarter

    DeKalb
    56.6%
    Miami
    63.3%

    By share, of 69 with 30+ tests

Read a result for DeKalb County

Starts at DeKalb County's median, 4.4 pCi/L

4.4pCi/L

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

EPA’s reading of 4.4 pCi/L

At or above 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 at or above 4 pCi/L. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. DeKalb County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

DeKalb County, At a glance

DeKalb County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of DeKalb 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 100% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, DeKalb County, 2008 to 2017, laboratory
Under 2 pCi/L: 20%2 to 4 pCi/L: 23%4 pCi/L and above: 57%

Of 242 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, DeKalb County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L4920.2%
2 to 4 pCi/L5623.1%
4 pCi/L and above13756.6%
What these figures count

These are the 242 tests reported to CDC for DeKalb 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

DeKalb County, Compared

DeKalb County radon figures, compared

Calculated by Radon411

More than half: 56.6% of the 242 radon tests reported to CDC for DeKalb County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 8th of 69 Indiana counties with 30 or more tests for the same period. That is 17.7 points above the 38.9% pooled from 92 Indiana counties.

The median result, 4.4 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 46.2 pCi/L. The rest split 20.2% under 2 pCi/L and 23.1% from 2 to 4 (Indiana: 32.8% and 28.3%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 56.6% share point the same way here.

No bordering county with a figure for the same period reported a higher share; the closest is Steuben County at 55.7%, the lowest LaGrange County at 41.7%. Statewide for the same period, Miami County reported the highest share (63.3%) and Jasper County the lowest (14.1%).

CDC's ten-year totals for DeKalb County went from 153 tests (2005 to 2014) to 242 (2008 to 2017), the share going from 61.4% to 56.6%.

Nationally, every county with a figure for the same period pools to 35.7%; DeKalb County sits 20.9 points above it. CDC also counts 20 tests taken after mitigation in DeKalb County for the same period: tests in homes where a fix was already in.

DeKalb County against Indiana, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from DeKalb County
DeKalb County24256.6%4.4 pCi/LThis county
Indiana, pooled92 counties, pooled43,14838.9%Not pooled−17.7 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−20.9 points
Miami Countyhighest in the state3063.3%5.3 pCi/L+6.7 points
Jasper Countylowest in the state7114.1%1.2 pCi/L−42.5 points
Steuben County, INborders it14055.7%4.5 pCi/L−0.9 points
Noble County, INborders it13652.9%4.3 pCi/L−3.7 points
Defiance County, OHborders it7048.6%3.8 pCi/L−8.0 points
Williams County, OHborders it2842.9%3.3 pCi/L−13.7 points
Allen County, INborders it3,99041.8%3.3 pCi/L−14.8 points
LaGrange County, INborders it12041.7%3.4 pCi/L−14.9 points
Where DeKalb County's reported results fell, 2008 to 2017, laboratory, beside Indiana and the United States
ResultDeKalb County testsDeKalb County shareIndiana shareU.S. shareAgainst Indiana
Under 2 pCi/L4920.2%32.8%39.6%−12.6 points
2 to 4 pCi/L5623.1%28.3%24.7%−5.2 points
4 pCi/L and above13756.6%38.9%35.7%+17.7 points
DeKalb 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
Benton County3 of 693461.8%5.7 pCi/L
Carroll County4 of 693860.5%5.8 pCi/L
Wabash County5 of 699159.3%5.8 pCi/L
Grant County6 of 697958.2%4.6 pCi/L
LaPorte County7 of 6979258.2%5.0 pCi/L
DeKalb County8 of 6924256.6%4.4 pCi/L
Wayne County9 of 6914056.4%4.5 pCi/L
Steuben County10 of 6914055.7%4.5 pCi/L
Delaware County11 of 6918755.1%4.2 pCi/L
Fountain County12 of 696055.0%4.6 pCi/L
Noble County13 of 6913652.9%4.3 pCi/L
DeKalb County ten-year laboratory totals, against Indiana's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestIndiana, pooledChange from the row before
2008 to 201724256.6%4.4 pCi/L46.2 pCi/L38.9%−3.1 points
2007 to 201620159.7%4.7 pCi/L46.2 pCi/L39.2%−3.3 points
2006 to 201517363.0%4.8 pCi/L46.2 pCi/L39.6%+1.6 points
2005 to 201415361.4%4.8 pCi/L46.2 pCi/L39.3%First on file

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

DeKalb County, Geology

The ground under DeKalb County

Predicted

USGS's geologic map puts all of DeKalb County's mapped land in one class: high radon potential. 99.3% of it lies in the area the map calls Huron-Erie Lobe, to which USGS gives a radon index of 13, in the high band (12 to 17).

USGS's geologic areas under DeKalb 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.High1399.3%

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

DeKalb County beside the ground around it

DeKalb County has more high-potential ground than Indiana as a whole: 100% of its land against 56.6%. Of the 6 counties that border it, none has as large a share of high-potential ground; LaGrange County comes nearest at 100%.

Share of land by USGS radon potential: DeKalb County, the 6 counties bordering it and Indiana
AreaEPA zoneLow potentialModerate potentialHigh potential
DeKalb CountyZone 1NoneNone100%
Allen CountyZone 1NoneNone100%
Steuben CountyZone 1NoneNone100%
Noble CountyZone 1NoneNone100%
Defiance County, OHZone 2None37.4%62.6%
Williams County, OHZone 2None9.7%90.3%
LaGrange CountyZone 1NoneNone100%
Indiana92 counties, pooled by land areaVariesNone43.4%56.6%

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

Local help

DeKalb County, Local resources

Radon testing and mitigation in DeKalb 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

DeKalb County, Questions

Questions about radon in DeKalb County

Are radon levels high in DeKalb County?

Over the 2008 to 2017 laboratory totals, 56.6% of the radon tests reported to CDC for DeKalb County, Indiana were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.4 pCi/L. Of 69 Indiana counties with 30 or more tests for the same period, 7 reported a higher share; pooled, the state comes to 38.9%.

Which counties border DeKalb County?

DeKalb County borders 6 counties: Allen County, IN, Steuben County, IN, Noble County, IN, Defiance County, OH, Williams County, OH and LaGrange County, IN.

Products

DeKalb County, Products

Testing a home in DeKalb County

In DeKalb County, 56.6% of 242 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 DeKalb 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

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

Explore

DeKalb County, Bordering counties

Counties bordering DeKalb County

Calculated by Radon411

DeKalb County, Cities and towns

Cities and towns in DeKalb County

The Census Bureau estimates 44,535 residents in DeKalb County for July 1, 2025, 1,243 more than in 2020 (+2.9%). That works out to 123 people per square mile of land. Its largest town, Auburn, has 14,068 residents, 31.6% of the total. CDC's 242 reported tests for 2008 to 2017 work out to 5.4 per 1,000 residents (2025 estimate), close to Indiana's 6.2.

From Auburn to Altona, CDC publishes no figure by town: each reads DeKalb County's.

The cities and towns in DeKalb County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Auburn14,068+3.9%31.6%
Garrett6,694+2.2%15.0%
Butler2,673+1.7%6.0%
Waterloo2,168+2.6%4.9%
Hamiltonextends beyond DeKalb County1,559+2.1%Counted whole
Ashleyextends beyond DeKalb County1,037+1.1%Counted whole
St. Joe429+4.1%1.0%
Corunna241+2.6%0.5%
Altona220+2.8%0.5%

9 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 DeKalb County is counted whole, so it has no share.

DeKalb County, Homes

Homes in DeKalb County

DeKalb County is a place of houses on their own lots: 79% of its 18,280 homes are detached single-family houses, against 73% across Indiana. Half of its homes were built before 1975, close to Indiana's 1976: 36% date from before 1960 and 19% from 2000 or later. Owners live in 82% of the occupied homes (Indiana: 70%), so for most households a test and a fix are their own to order.

Homes in DeKalb County, Indiana, 2019 to 2023
HomesDeKalb CountyIndiana
Housing units18,2802,953,344
Detached houses79%73%
In buildings of 5 or more6%13%
Mobile homes8%4%
Built before 196036%32%
Built since 200019%21%
Middle year built19751976
Owner-occupied82%70%

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