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Radon Levels in Miami County, Indiana

EPA puts Miami County in Zone 1, its highest radon zone, and high results are common there: 63.3% of the 30 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

How to test this homeFind a certified tester

  • Share at 4+ pCi/L

    63.3%

    24.4 pts above IN

    Miami
    63.3%
    Indiana
    38.9%

    30 tests, 2008 to 2017

  • Median result

    5.3pCi/L

    Action level reached

    Miami
    5.3 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    30

    69th of 69 by tests

    Miami
    30
    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

    1 of 69

    Top quarter

    Miami
    63.3%
    Miami
    63.3%

    By share, of 69 with 30+ tests

Read a result for Miami County

Starts at Miami County's median, 5.3 pCi/L

5.3pCi/L

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

EPA’s reading of 5.3 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. Miami County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Miami County, At a glance

Miami County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

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

Reported results by concentration band, Miami County, 2008 to 2017, laboratory
Under 2 pCi/L: 17%2 to 4 pCi/L: 20%4 pCi/L and above: 63%

Of 30 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Miami County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L516.7%
2 to 4 pCi/L620.0%
4 pCi/L and above1963.3%
What these figures count

These are the 30 tests reported to CDC for Miami 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

Miami County, Compared

Miami County radon figures, compared

Calculated by Radon411

More than half: 63.3% of the 30 radon tests reported to CDC for Miami County over the 2008 to 2017 laboratory totals read at least 4 pCi/L. That places it 1st of 69 Indiana counties with 30 or more tests for the same period. That is 24.4 points above the 38.9% pooled from 92 Indiana counties.

The median result, 5.3 pCi/L, sits above EPA's 4 pCi/L action level, and the top reported result was 72.4 pCi/L. The rest split 16.7% under 2 pCi/L and 20.0% from 2 to 4 (Indiana: 32.8% and 28.3%). Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 63.3% share point the same way here.

No bordering county with a figure for the same period reported a higher share; the closest is Wabash County at 59.3%, the lowest Cass County at 34.1%. Statewide for the same period, Harrison County reported the highest share (62.4%) and Jasper County the lowest (14.1%).

CDC's ten-year totals for Miami County went from 24 tests (2005 to 2014) to 30 (2008 to 2017), the share going from 58.3% to 63.3%.

Nationally, every county with a figure for the same period pools to 35.7%; Miami County sits 27.6 points above it.

Miami County against Indiana, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Miami County
Miami County3063.3%5.3 pCi/LThis county
Indiana, pooled92 counties, pooled43,14838.9%Not pooled−24.4 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled−27.6 points
Harrison Countyhighest in the state22162.4%5.5 pCi/L−0.9 points
Jasper Countylowest in the state7114.1%1.2 pCi/L−49.2 points
Wabash County, INborders it9159.3%5.8 pCi/L−4.0 points
Grant County, INborders it7958.2%4.6 pCi/L−5.1 points
Howard County, INborders it21649.1%3.8 pCi/L−14.2 points
Fulton County, INborders it9746.4%3.3 pCi/L−16.9 points
Cass County, INborders it9134.1%2.6 pCi/L−29.2 points
Where Miami County's reported results fell, 2008 to 2017, laboratory, beside Indiana and the United States
ResultMiami County testsMiami County shareIndiana shareU.S. shareAgainst Indiana
Under 2 pCi/L516.7%32.8%39.6%−16.1 points
2 to 4 pCi/L620.0%28.3%24.7%−8.3 points
4 pCi/L and above1963.3%38.9%35.7%+24.4 points
Miami 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
Miami County1 of 693063.3%5.3 pCi/L
Harrison County2 of 6922162.4%5.5 pCi/L
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
Miami County ten-year laboratory totals, against Indiana's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestIndiana, pooledChange from the row before
2008 to 20173063.3%5.3 pCi/L72.4 pCi/L38.9%+1.8 points
2007 to 20162661.5%4.9 pCi/L72.4 pCi/L39.2%+5.0 points
2006 to 20152356.5%4.7 pCi/L72.4 pCi/L39.6%−1.8 points
2005 to 20142458.3%4.8 pCi/L72.4 pCi/L39.3%First on file

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

Miami County, Geology

The ground under Miami County

Predicted

USGS's geologic map puts all of Miami County's mapped land in one class: high radon potential. The map puts 88.8% of Miami County in the area it calls Huron-Erie Lobe and 11.2% in Saginaw Lobe. USGS gives the first a radon index of 13 and the second 12, both in the high band (12 to 17).

USGS's geologic areas under Miami 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.High1388.8%
Saginaw LobeClayey and loamy glacial deposits.High1211.2%

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

Miami County beside the ground around it

Miami County has more high-potential ground than Indiana as a whole: 100% of its land against 56.6%. Of the 5 counties that border it, none has as large a share of high-potential ground; Fulton County comes nearest at 100%.

Share of land by USGS radon potential: Miami County, the 5 counties bordering it and Indiana
AreaEPA zoneLow potentialModerate potentialHigh potential
Miami CountyZone 1NoneNone100%
Wabash CountyZone 1NoneNone100%
Cass CountyZone 1NoneNone100%
Howard CountyZone 1NoneNone100%
Fulton CountyZone 1NoneNone100%
Grant CountyZone 1NoneNone100%
Indiana92 counties, pooled by land areaVariesNone43.4%56.6%

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

Local help

Miami County, Local resources

Radon testing and mitigation in Miami 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

Miami County, Questions

Questions about radon in Miami County

Are radon levels high in Miami County?

Over the 2008 to 2017 laboratory totals, 63.3% of the radon tests reported to CDC for Miami County, Indiana were at or above 4 pCi/L, and the median reported pre-mitigation result was 5.3 pCi/L. Of 69 Indiana counties with 30 or more tests for the same period, none reported a higher share; pooled, the state comes to 38.9%.

Which counties border Miami County?

Miami County borders 5 counties: Wabash County, Cass County, Howard County, Fulton County and Grant County.

Products

Miami County, Products

Testing a home in Miami County

In Miami County, 63.3% of 30 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 Miami 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

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

Explore

Miami County, Bordering counties

Counties bordering Miami County

Calculated by Radon411

Miami County, Cities and towns

Cities and towns in Miami County

About 34,487 people live in Miami County by the Census Bureau's estimate for July 1, 2025, 1,420 fewer than in 2020 (−4.0%). That works out to 92 people per square mile of land. Its largest town, Peru, has 10,962 residents, 31.8% of the total. Reported testing is thin here: 30 tests over 2008 to 2017, or 0.9 for every 1,000 residents (2025 estimate), where Indiana as a whole comes to 6.2.

From Peru to Macy, CDC publishes no figure by town: each reads Miami County's.

The cities and towns in Miami County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Peru10,962+0.2%31.8%
Converseextends beyond Miami County1,128−2.3%Counted whole
Bunker Hill828+1.2%2.4%
Denver465−2.3%1.3%
Amboy309−2.2%0.9%
Macy194−2.5%0.6%

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 Miami County is counted whole, so it has no share.

Miami County, Homes

Homes in Miami County

Miami County is a place of houses on their own lots: 76% of its 14,927 homes are detached single-family houses, against 73% across Indiana. The homes are older than Indiana's as a whole: half were built before 1962 (1976 for Indiana), and 48% date from before 1960. Owners live in 75% of the occupied homes (Indiana: 70%), so for most households a test and a fix are their own to order.

Homes in Miami County, Indiana, 2019 to 2023
HomesMiami CountyIndiana
Housing units14,9272,953,344
Detached houses76%73%
In buildings of 5 or more4%13%
Mobile homes9%4%
Built before 196048%32%
Built since 20009%21%
Middle year built19621976
Owner-occupied75%70%

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