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Radon Levels in Delaware County, Indiana

EPA puts Delaware County in Zone 1, its highest radon zone, and high results are common there: 55.1% of the 187 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

    55.1%

    16.2 pts above IN

    Delaware
    55.1%
    Indiana
    38.9%

    187 tests, 2008 to 2017

  • Median result

    4.2pCi/L

    Action level reached

    Delaware
    4.2 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    187

    30th of 69 by tests

    Delaware
    187
    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

    11 of 69

    Top quarter

    Delaware
    55.1%
    Miami
    63.3%

    By share, of 69 with 30+ tests

Read a result for Delaware County

Starts at Delaware County's median, 4.2 pCi/L

4.2pCi/L

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

EPA’s reading of 4.2 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. Delaware County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Delaware County, At a glance

Delaware County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Delaware 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 Delaware County, 2008 to 2017, laboratory

Reported results by concentration band, Delaware County, 2008 to 2017, laboratory
Under 2 pCi/L: 24%2 to 4 pCi/L: 21%4 pCi/L and above: 55%

Of 187 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Delaware County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L4423.5%
2 to 4 pCi/L4021.4%
4 pCi/L and above10355.1%
What these figures count

These are the 187 tests reported to CDC for Delaware 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

Delaware County, Compared

Delaware County radon figures, compared

Calculated by Radon411

More than half: 55.1% of the 187 radon tests reported to CDC for Delaware County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 11th of 69 Indiana counties with 30 or more tests for the same period. That is 16.2 points above the 38.9% pooled from 92 Indiana counties.

The median result, 4.2 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 53.6 pCi/L. The rest split 23.5% under 2 pCi/L and 21.4% from 2 to 4 (Indiana: 32.8% and 28.3%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 55.1% share point the same way here.

1 of its 3 bordering counties with figures ran higher, led by Grant County at 58.2%; Madison County reported 49.0%. 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 Delaware County went from 213 tests (2005 to 2014) to 187 (2008 to 2017), the share going from 45.5% to 55.1%.

Nationally, every county with a figure for the same period pools to 35.7%; Delaware County sits 19.4 points above it. CDC also counts 25 tests taken after mitigation in Delaware County for the same period: tests in homes where a fix was already in.

Delaware County against Indiana, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Delaware County
Delaware County18755.1%4.2 pCi/LThis county
Indiana, pooled92 counties, pooled43,14838.9%Not pooled−16.2 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−19.4 points
Miami Countyhighest in the state3063.3%5.3 pCi/L+8.2 points
Jasper Countylowest in the state7114.1%1.2 pCi/L−41.0 points
Randolph County, INborders it2860.7%4.5 pCi/L+5.6 points
Grant County, INborders it7958.2%4.6 pCi/L+3.1 points
Henry County, INborders it9550.5%4.0 pCi/L−4.6 points
Madison County, INborders it23949.0%3.8 pCi/L−6.1 points
Jay County, INborders it944.4%2.7 pCi/L−10.7 points
Blackford County, INborders it1136.4%3.6 pCi/L−18.7 points
Where Delaware County's reported results fell, 2008 to 2017, laboratory, beside Indiana and the United States
ResultDelaware County testsDelaware County shareIndiana shareU.S. shareAgainst Indiana
Under 2 pCi/L4423.5%32.8%39.6%−9.3 points
2 to 4 pCi/L4021.4%28.3%24.7%−6.9 points
4 pCi/L and above10355.1%38.9%35.7%+16.2 points
Delaware 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
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
Whitley County14 of 6918451.6%4.0 pCi/L
Kosciusko County15 of 691,24850.6%4.0 pCi/L
Henry County16 of 699550.5%4.0 pCi/L
Delaware County ten-year laboratory totals, against Indiana's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestIndiana, pooledChange from the row before
2008 to 201718755.1%4.2 pCi/L53.6 pCi/L38.9%+5.4 points
2007 to 201618149.7%3.8 pCi/L53.6 pCi/L39.2%−0.6 points
2006 to 201519950.3%4.0 pCi/L53.0 pCi/L39.6%+4.8 points
2005 to 201421345.5%3.4 pCi/L53.0 pCi/L39.3%First on file

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

Delaware County, Geology

The ground under Delaware County

Predicted

USGS's geologic map puts all of Delaware County's mapped land in one class: high radon potential. All 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 Delaware 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.High13100%

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

Delaware County beside the ground around it

Delaware 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; Blackford County comes nearest at 100%.

Share of land by USGS radon potential: Delaware County, the 6 counties bordering it and Indiana
AreaEPA zoneLow potentialModerate potentialHigh potential
Delaware CountyZone 1NoneNone100%
Madison CountyZone 1NoneNone100%
Henry CountyZone 1NoneNone100%
Blackford CountyZone 1NoneNone100%
Randolph CountyZone 1NoneNone100%
Grant CountyZone 1NoneNone100%
Jay CountyZone 1NoneNone100%
Indiana92 counties, pooled by land areaVariesNone43.4%56.6%

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

Local help

Delaware County, Local resources

Radon testing and mitigation in Delaware 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

Delaware County, Questions

Questions about radon in Delaware County

Are radon levels high in Delaware County?

Over the 2008 to 2017 laboratory totals, 55.1% of the radon tests reported to CDC for Delaware County, Indiana were at or above 4 pCi/L, and the median reported pre-mitigation result was 4.2 pCi/L. Of 69 Indiana counties with 30 or more tests for the same period, 10 reported a higher share; pooled, the state comes to 38.9%.

Which counties border Delaware County?

Delaware County borders 6 counties: Madison County, Henry County, Blackford County, Randolph County, Grant County and Jay County.

Products

Delaware County, Products

Testing a home in Delaware County

In Delaware County, 55.1% of 187 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 Delaware 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

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

Explore

Delaware County, Bordering counties

Counties bordering Delaware County

Calculated by Radon411

Delaware County, Cities and towns

Cities and towns in Delaware County

The Census Bureau estimates 113,106 residents in Delaware County for July 1, 2025, 1,342 more than in 2020 (+1.2%). That works out to 288 people per square mile of land. Muncie alone is home to 65,466 of them, 57.9% of the total. Reported testing is thin here: 187 tests over 2008 to 2017, or 1.7 for every 1,000 residents (2025 estimate), where Indiana as a whole comes to 6.2.

From Muncie to Selma, CDC publishes no figure by town: each reads Delaware County's.

The cities and towns in Delaware County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Muncie65,466+0.6%57.9%
Yorktown11,947+3.5%10.6%
Chesterfieldextends beyond Delaware County2,523+1.7%Counted whole
Albanyextends beyond Delaware County2,269−0.4%Counted whole
Daleville1,706+3.2%1.5%
Eaton1,586−0.3%1.4%
Gaston806+1.1%0.7%
Selma741−0.4%0.7%

8 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 Delaware County is counted whole, so it has no share.

Delaware County, Homes

Homes in Delaware County

Of Delaware County's 51,611 homes, 73% are detached houses, against 73% across Indiana; 12% are in buildings of five or more homes. The homes are older than Indiana's as a whole: half were built before 1966 (1976 for Indiana), and 40% date from before 1960. 66% 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 Delaware County, Indiana, 2019 to 2023
HomesDelaware CountyIndiana
Housing units51,6112,953,344
Detached houses73%73%
In buildings of 5 or more12%13%
Mobile homes5%4%
Built before 196040%32%
Built since 200012%21%
Middle year built19661976
Owner-occupied66%70%

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