Skip to content
RADON411

Locations and reports

Radon Levels in St. Joseph County, Michigan

EPA puts St. Joseph County in Zone 1, its highest radon zone, and 34.1% of its 1,068 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

    34.1%

    7.2 pts above MI

    St. Joseph
    34.1%
    Michigan
    26.9%

    1,068 tests, 2008 to 2017

  • Median result

    2.9pCi/L

    Below action level

    St. Joseph
    2.9 pCi/L
    EPA
    4.0 pCi/L

    Midpoint of the tests, 2008 to 2017

  • Tests reported

    1,068

    29th of 82 by tests

    St. Joseph
    1,068
    Oakland
    16,224

    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 Michigan

    15 of 82

    Top quarter

    St. Joseph
    34.1%
    Lenawee
    56.7%

    By share, of 82 with 30+ tests

Read a result for St. Joseph County

Starts at St. Joseph County's median, 2.9 pCi/L

2.9pCi/L

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

EPA’s reading of 2.9 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. St. Joseph County's median reported result, 2008 to 2017.

Interpret this readingWhat a fix costs

The data

St. Joseph County, At a glance

St. Joseph County at a glance

Predicted: EPA radon zone

EPA Zone 1: highest predicted potential

EPA puts all of St. Joseph 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 St. Joseph County, 2008 to 2017, laboratory

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

Of 1,068 pre-mitigation tests reported to CDC, not homes in this area.

Reported results by concentration band, St. Joseph County, 2008 to 2017, laboratory: data table
Result bandTests MeasuredShare Measured
Under 2 pCi/L36334.0%
2 to 4 pCi/L34131.9%
4 pCi/L and above36434.1%
What these figures count

These are the 1,068 tests reported to CDC for St. Joseph 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

St. Joseph County, Compared

St. Joseph County radon figures, compared

Calculated by Radon411

In St. Joseph County, about 3 in 10 reported tests over the 2008 to 2017 laboratory totals (364 of 1,068) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 1.6 points lower. Across 83 Michigan counties pooled together, 26.9% of tests reached that level, so St. Joseph County runs 7.2 points above its state.

Of 7 neighbours with a figure, 4 reported a larger share at or above 4 pCi/L and 3 a smaller one; the spread is 18.0% (Van Buren County) to 55.4% (Branch County). By share, St. Joseph County is 15th of 82 Michigan counties with 30 or more tests for the same period.

Half the tests came in under 2.9 pCi/L and half over it; the single highest reached 42.9 pCi/L. Below the action level, 363 tests (34.0%) came in under 2 pCi/L, against 46.4% statewide, and 341 tests (31.9%) fell between 2 and 4, against 26.7% statewide.

Zone 1 on EPA's map (predicted average above 4 pCi/L) and a 34.1% share point the same way here. USGS geology rates 100% of the county's land high radon potential. CDC also counts 44 tests taken after mitigation in St. Joseph County for the same period: tests in homes where a fix was already in.

CDC's ten-year totals for St. Joseph County went from 973 tests (2005 to 2014) to 1,068 (2008 to 2017), the share going from 32.6% to 34.1%.

St. Joseph County against Michigan, the United States and nearby counties, 2008 to 2017, laboratory
AreaTestsAt or above 4 pCi/LMedianDifference from St. Joseph County
St. Joseph County1,06834.1%2.9 pCi/LThis county
Michigan, pooled83 counties, pooled114,40726.9%Not pooled−7.2 points
United States, pooled2,661 counties, pooled2,013,54435.7%Not pooled+1.6 points
Lenawee Countyhighest in the state1,90756.7%4.6 pCi/L+22.6 points
Muskegon Countylowest in the state6293.2%1.2 pCi/L−30.9 points
Branch County, MIborders it1,04855.4%4.4 pCi/L+21.3 points
Elkhart County, INborders it2,85646.4%3.7 pCi/L+12.3 points
LaGrange County, INborders it12041.7%3.4 pCi/L+7.6 points
Calhoun County, MIborders it1,64936.4%3.0 pCi/L+2.3 points
Kalamazoo County, MIborders it4,10033.3%2.8 pCi/L−0.8 points
Cass County, MIborders it57230.4%2.6 pCi/L−3.7 points
Van Buren County, MIborders it39418.0%1.9 pCi/L−16.1 points
Where St. Joseph County's reported results fell, 2008 to 2017, laboratory, beside Michigan and the United States
ResultSt. Joseph County testsSt. Joseph County shareMichigan shareU.S. shareAgainst Michigan
Under 2 pCi/L36334.0%46.4%39.6%−12.4 points
2 to 4 pCi/L34131.9%26.7%24.7%+5.2 points
4 pCi/L and above36434.1%26.9%35.7%+7.2 points
St. Joseph County ranked among the 82 Michigan counties with 30 or more tests, by share at or above 4 pCi/L, 2008 to 2017, laboratory
CountyRankTestsAt or above 4 pCi/LMedian
Ionia County10 of 821,39136.8%2.9 pCi/L
Calhoun County11 of 821,64936.4%3.0 pCi/L
Iron County12 of 8226536.2%2.6 pCi/L
Tuscola County13 of 8236935.5%2.6 pCi/L
Eaton County14 of 823,41134.4%2.8 pCi/L
St. Joseph County15 of 821,06834.1%2.9 pCi/L
Lapeer County16 of 8264933.4%2.7 pCi/L
Kalamazoo County17 of 824,10033.3%2.8 pCi/L
Shiawassee County18 of 821,51531.6%2.5 pCi/L
Barry County19 of 821,61530.7%2.6 pCi/L
Cass County20 of 8257230.4%2.6 pCi/L
St. Joseph County ten-year laboratory totals, against Michigan's pooled share
PeriodTestsAt or above 4 pCi/LMedianHighestMichigan, pooledChange from the row before
2008 to 20171,06834.1%2.9 pCi/L42.9 pCi/L26.9%+0.1 points
2007 to 20161,02834.0%2.8 pCi/L35.9 pCi/L26.8%+1.1 points
2006 to 20151,02332.9%2.8 pCi/L35.9 pCi/L26.8%+0.3 points
2005 to 201497332.6%2.7 pCi/L35.9 pCi/L26.2%First on file

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

St. Joseph County, State data

Michigan's own radon test data

Measured

What Michigan's own agencies publish about radon tests in St. Joseph County, with their period. These are not CDC's figures and are never added to them.

MeasuredState figures, not CDC's

What Michigan EGLE reports for the ZIP codes in St. Joseph County

Michigan EGLE publishes its figures by ZIP code, not by county. These are the 12 ZIP codes that lie wholly or partly in St. Joseph County, each with the state's own figures for it. Period: About 10 years to 2026-05-15.

ZIP codes in St. Joseph County
ZIP codeWhat the state reports
4901123% greater than 4 pCi/L, median 2.1 pCi/L, 13 tests
4903019% greater than 4 pCi/L, median 1.9 pCi/L, 16 tests
4903220% greater than 4 pCi/L, median 2.5 pCi/L, 10 tests
4904033% greater than 4 pCi/L, median 2.4 pCi/L, 21 tests
490420% greater than 4 pCi/L, median 2.0 pCi/L, 16 tests
490662 tests, figures not shown
4906723% greater than 4 pCi/L, median 2.0 pCi/L, 13 tests
4907258% greater than 4 pCi/L, median 4.7 pCi/L, 12 tests
4909139% greater than 4 pCi/L, median 3.1 pCi/L, 84 tests
4909334% greater than 4 pCi/L, median 3.0 pCi/L, 73 tests
4909731% greater than 4 pCi/L, median 2.7 pCi/L, 58 tests
4909955% greater than 4 pCi/L, median 4.1 pCi/L, 31 tests
  • EGLE's figures cover first-time tests only, from organizations willing to provide data.
  • EGLE does not publish figures for a ZIP code with fewer than 5 test results.
  • EGLE says the map is not intended to decide whether a home should be tested: all homes should be tested.
  • ZIP code boundaries are postal delivery areas, not legal or administrative boundaries.
  • A ZIP code that crosses the county line is listed whole; its figures cover all of it.

Measured: Michigan EGLE data, About 10 years to 2026-05-15.

St. Joseph County, Geology

The ground under St. Joseph County

Predicted

USGS's geologic map puts all of St. Joseph County's mapped land in one class: high radon potential. All of it lies in the area the map calls Saginaw Lobe Moraine Area, to which USGS gives a radon index of 12, in the high band (12 to 17).

USGS's geologic areas under St. Joseph County
AreaThe rock, in USGS's wordsPotentialRadon indexShare of land
Saginaw Lobe Moraine AreaGlacial deposits derived from Sandstone and shale.High1299.6%

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

St. Joseph County beside the ground around it

St. Joseph County has more high-potential ground than Michigan as a whole: 100% of its land against 9.6%. Of the 7 counties that border it, none has as large a share of high-potential ground; Branch County comes nearest at 100%.

Share of land by USGS radon potential: St. Joseph County, the 7 counties bordering it and Michigan
AreaEPA zoneLow potentialModerate potentialHigh potential
St. Joseph CountyZone 1NoneNone100%
LaGrange County, INZone 1NoneNone100%
Kalamazoo CountyZone 114.1%2.3%83.6%
Cass CountyZone 134.5%None65.5%
Branch CountyZone 1NoneNone100%
Elkhart County, INZone 1NoneNone100%
Calhoun CountyZone 1None25.0%75.0%
Van Buren CountyZone 397.9%None2.1%
Michigan83 counties, pooled by land areaVaries45.0%44.3%9.6%

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

Local help

St. Joseph County, Local resources

Radon testing and mitigation in St. Joseph County

What Michigan's program says
Phone
800-723-6642
Email
Radon@Michigan.gov
Licensing of radon professionals
Michigan does not license or regulate radon testing and mitigation contractors.

What it means

St. Joseph County, Questions

Questions about radon in St. Joseph County

Are radon levels high in St. Joseph County?

Over the 2008 to 2017 laboratory totals, 34.1% of the radon tests reported to CDC for St. Joseph County, Michigan were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.9 pCi/L. Of 82 Michigan counties with 30 or more tests for the same period, 14 reported a higher share; pooled, the state comes to 26.9%.

Which counties border St. Joseph County?

St. Joseph County borders 7 counties: LaGrange County, IN, Kalamazoo County, MI, Cass County, MI, Branch County, MI, Elkhart County, IN, Calhoun County, MI and Van Buren County, MI.

Products

St. Joseph County, Products

Testing a home in St. Joseph County

In St. Joseph County, 34.1% of 1,068 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 26.9% pooled across Michigan. In Zone 1 the year-round level in St. Joseph 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

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

Explore

St. Joseph County, Bordering counties

Counties bordering St. Joseph County

Calculated by Radon411

St. Joseph County, Cities and towns

Cities and towns in St. Joseph County

St. Joseph County's population has barely moved since 2020: 60,968 residents on July 1, 2025 against 60,923 then, by the Census Bureau's estimates. That works out to 122 people per square mile of land. No town dominates: Sturgis, the largest, has 10,900 residents, 17.9% of the total. Together its 8 incorporated places hold 43.9% of those residents; the other 56.1% live outside any of them. Testing is reported here more often than across the state: CDC's 1,068 reported tests for 2008 to 2017 come to 17.5 for every 1,000 residents (2025 estimate), against 11.3 for Michigan.

From Sturgis to Burr Oak, CDC publishes no figure by town: each reads St. Joseph County's.

The cities and towns in St. Joseph County by residents, July 1, 2025
PlaceResidentsSince 2020Share of residents
Sturgis10,900−2.0%17.9%
Three Rivers7,910−0.8%13.0%
Constantine1,983−0.2%3.3%
White Pigeon1,824+5.7%3.0%
Centreville1,374+5.0%2.3%
Colon1,182−2.2%1.9%
Mendon862−2.7%1.4%
Burr Oak755−2.2%1.2%

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).

St. Joseph County, Homes

Homes in St. Joseph County

St. Joseph County is a place of houses on their own lots: 78% of its 27,248 homes are detached single-family houses, against 72% across Michigan. Half of its homes were built before 1970, close to Michigan's 1972: 42% date from before 1960 and 12% from 2000 or later. Owners live in 75% of the occupied homes (Michigan: 73%), so for most households a test and a fix are their own to order.

Homes in St. Joseph County, Michigan, 2019 to 2023
HomesSt. Joseph CountyMichigan
Housing units27,2484,599,683
Detached houses78%72%
In buildings of 5 or more9%13%
Mobile homes8%5%
Built before 196042%36%
Built since 200012%15%
Middle year built19701972
Owner-occupied75%73%

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