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Radon Levels in Monroe County, Indiana

EPA puts Monroe County in Zone 1, its highest radon zone, and 34.2% of its 2,375 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

    34.2%

    4.7 pts below IN

    Monroe
    34.2%
    Indiana
    38.9%

    2,375 tests, 2008 to 2017

  • Median result

    2.8pCi/L

    Below action level

    Monroe
    2.8 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    2,375

    6th of 69 by tests

    Monroe
    2,375
    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

    56 of 69

    Lowest quarter

    Monroe
    34.2%
    Miami
    63.3%

    By share, of 69 with 30+ tests

Read a result for Monroe County

Starts at Monroe County's median, 2.8 pCi/L

2.8pCi/L

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

EPA’s reading of 2.8 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. Monroe County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

Monroe County, At a glance

Monroe County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of Monroe 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: Moderate across 100% of the county's area

Predicted: EPA Map of Radon Zones

Measured: tests reported to CDC

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

Reported results by concentration band, Monroe County, 2008 to 2017, laboratory
Under 2 pCi/L: 34%2 to 4 pCi/L: 32%4 pCi/L and above: 34%

Of 2,375 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, Monroe County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L81334.2%
2 to 4 pCi/L75031.6%
4 pCi/L and above81234.2%
What these figures count

These are the 2,375 tests reported to CDC for Monroe 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

Monroe County, Compared

Monroe County radon figures, compared

Calculated by Radon411

In Monroe County, about 3 in 10 reported tests over the 2008 to 2017 laboratory totals (812 of 2,375) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 1.5 points lower. Across 92 Indiana counties pooled together, 38.9% of tests reached that level, so Monroe County runs 4.7 points below its state.

Of 6 neighbours with a figure, 3 reported a larger share at or above 4 pCi/L and 3 a smaller one; the spread is 25.9% (Brown County) to 44.2% (Morgan County). By share, Monroe County is 56th of 69 Indiana counties with 30 or more tests for the same period.

Half the tests came in under 2.8 pCi/L and half over it; the single highest reached 95.7 pCi/L. Below the action level, 813 tests (34.2%) came in under 2 pCi/L, against 32.8% statewide, and 750 tests (31.6%) fell between 2 and 4, against 28.3% statewide.

Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 34.2% share point the same way here. USGS geology rates 100% of the county's land moderate radon potential. CDC also counts 257 tests taken after mitigation in Monroe County for the same period: tests in homes where a fix was already in.

CDC's ten-year totals for Monroe County went from 1,609 tests (2005 to 2014) to 2,375 (2008 to 2017), the share going from 36.2% to 34.2%.

Monroe County against Indiana, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from Monroe County
Monroe County2,37534.2%2.8 pCi/LThis county
Indiana, pooled92 counties, pooled43,14838.9%Not pooled+4.7 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+1.5 points
Miami Countyhighest in the state3063.3%5.3 pCi/L+29.1 points
Jasper Countylowest in the state7114.1%1.2 pCi/L−20.1 points
Morgan County, INborders it22644.2%3.5 pCi/L+10.0 points
Owen County, INborders it11039.1%2.8 pCi/L+4.9 points
Lawrence County, INborders it26735.6%2.7 pCi/L+1.4 points
Greene County, INborders it4932.7%3.0 pCi/L−1.5 points
Jackson County, INborders it8827.3%2.8 pCi/L−6.9 points
Brown County, INborders it11225.9%2.8 pCi/L−8.3 points
Where Monroe County's reported results fell, 2008 to 2017, laboratory, beside Indiana and the United States
ResultMonroe County testsMonroe County shareIndiana shareU.S. shareAgainst Indiana
Under 2 pCi/L81334.2%32.8%39.6%+1.4 points
2 to 4 pCi/L75031.6%28.3%24.7%+3.3 points
4 pCi/L and above81234.2%38.9%35.7%−4.7 points
Monroe 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
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
Dearborn County61 of 6913630.1%2.6 pCi/L
Monroe County ten-year laboratory totals, against Indiana's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestIndiana, pooledChange from the row before
2008 to 20172,37534.2%2.8 pCi/L95.7 pCi/L38.9%−0.1 points
2007 to 20162,24134.3%2.7 pCi/L95.7 pCi/L39.2%−1.7 points
2006 to 20151,97036.0%2.8 pCi/L95.7 pCi/L39.6%−0.2 points
2005 to 20141,60936.2%2.9 pCi/L60.0 pCi/L39.3%First on file

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

Monroe County, Geology

The ground under Monroe County

Predicted

USGS's geologic map puts all of Monroe County's mapped land in one class: moderate radon potential. All of it lies in the area the map calls Crawford Upland/Mitchell Plain/Norman Upland, to which USGS gives a radon index of 11, in the moderate band (9 to 11).

USGS's geologic areas under Monroe County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Crawford Upland/Mitchell Plain/Norman UplandUnglaciated, underlain by karsted Mississippian carbonate rocks.Moderate11100%

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

Monroe County beside the ground around it

Across Indiana 56.6% of the land is rated high; none of Monroe County's is. Of the 6 counties that border it, 3 have more high-potential ground, Morgan County the most at 55.6%.

Share of land by USGS radon potential: Monroe County, the 6 counties bordering it and Indiana
AreaEPA zoneLow potentialModerate potentialHigh potential
Monroe CountyZone 1None100%None
Brown CountyZone 2None99.3%0.7%
Owen CountyZone 2None100%None
Morgan CountyZone 2None44.4%55.6%
Greene CountyZone 2None100%None
Lawrence CountyZone 1None100%None
Jackson CountyZone 2None79.6%20.4%
Indiana92 counties, pooled by land areaVariesNone43.4%56.6%

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

Local help

Monroe County, Local resources

Radon testing and mitigation in Monroe 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

Monroe County, Questions

Questions about radon in Monroe County

Are radon levels high in Monroe County?

Over the 2008 to 2017 laboratory totals, 34.2% of the radon tests reported to CDC for Monroe County, Indiana were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.8 pCi/L. Of 69 Indiana counties with 30 or more tests for the same period, 55 reported a higher share; pooled, the state comes to 38.9%.

Which counties border Monroe County?

Monroe County borders 6 counties: Brown County, Owen County, Morgan County, Greene County, Lawrence County and Jackson County.

Products

Monroe County, Products

Testing a home in Monroe County

In Monroe County, 34.2% of 2,375 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 Monroe 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

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

Explore

Monroe County, Bordering counties

Counties bordering Monroe County

Calculated by Radon411

Monroe County, Cities and towns

Cities and towns in Monroe County

The Census Bureau estimates 143,345 residents in Monroe County for July 1, 2025, 2,716 more than in 2020 (+1.9%). That works out to 363 people per square mile of land. Bloomington alone is home to 83,307 of them, 58.1% of the total. Together its 3 incorporated places hold 63.0% of those residents; the other 37.0% live outside any of them. Testing is reported here more often than across the state: CDC's 2,375 reported tests for 2008 to 2017 come to 16.6 for every 1,000 residents (2025 estimate), against 6.2 for Indiana.

From Bloomington to Stinesville, CDC publishes no figure by town: each reads Monroe County's.

The cities and towns in Monroe County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Bloomington83,307+4.0%58.1%
Ellettsville6,840+3.2%4.8%
Stinesville197−1.0%0.1%

3 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).

Monroe County, Homes

Homes in Monroe County

Fewer than six in ten of Monroe County's 64,850 homes are detached houses (54%, against 73% across Indiana); the rest are attached, in shared buildings or mobile. Much of Monroe County is recent building: 26% of its homes have gone up since 2000 and the middle year built is 1986, against 1976 for Indiana. 55% 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 Monroe County, Indiana, 2019 to 2023
HomesMonroe CountyIndiana
Housing units64,8502,953,344
Detached houses54%73%
In buildings of 5 or more28%13%
Mobile homes5%4%
Built before 196018%32%
Built since 200026%21%
Middle year built19861976
Owner-occupied55%70%

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