Short-term kit
Air Chek Short-Term radon test kit you hang, lab fee included
- Lab fee included
In home: 72 to 168 hours
Locations and reports
Radon Levels in Monroe County, Michigan
EPA puts Monroe County in Zone 2, its middle radon zone, and 30.4% of its 1,375 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
Share at 4+ pCi/L
30.4%
3.5 pts above MI
- Monroe
- 30.4%
- Michigan
- 26.9%
1,375 tests, 2008 to 2017
Median result
2.5pCi/L
Below action level
- Monroe
- 2.5 pCi/L
- EPA
- 4.0 pCi/L
Midpoint of the tests, 2008 to 2017
Tests reported
1,375
23rd of 82 by tests
- Monroe
- 1,375
- Oakland
- 16,224
Reported to CDC before any fix, 2008 to 2017
EPA radon zone
Zone 2
Moderate potential
- 1
- Zone 2
- 3
1 highest, 3 lowest
EPA predicts 2 to 4 pCi/L indoors
Rank in Michigan
21 of 82
Top quarter
- Monroe
- 30.4%
- Lenawee
- 56.7%
By share, of 82 with 30+ tests
Read a result for Monroe County
Starts at Monroe County's median, 2.5 pCi/L
EPA’s own thresholds; the figures are the area’s, never this home’s.
EPA’s reading of 2.5 pCi/L
Between 2 and 4 pCi/L
- Under 20 to 1.9 pCi/L
- 2 to 4consider a fix
- 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.
The data
Monroe County, At a glance
Monroe County at a glance
Predicted: EPA radon zone
EPA Zone 2: moderate predicted potential
Monroe County is a
USGS geologic potential: Moderate across 98% 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
Under 2 pCi/L: 39%2 to 4 pCi/L: 31%4 pCi/L and above: 30%
Of 1,375 pre-mitigation tests reported to CDC, not homes in this area.
| Result band | Tests Measured | Share Measured |
|---|---|---|
| Under 2 pCi/L | 538 | 39.1% |
| 2 to 4 pCi/L | 419 | 30.5% |
| 4 pCi/L and above | 418 | 30.4% |
What these figures count
These are the 1,375 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).
Monroe County, Compared
Monroe County radon figures, compared
Calculated by Radon411In Monroe County, about 3 in 10 reported tests over the 2008 to 2017 laboratory totals (418 of 1,375) were at or above EPA's action level. Against the national pool of 35.7%, the gap is 5.3 points lower. Across 83 Michigan counties pooled together, 26.9% of tests reached that level, so Monroe County runs 3.5 points above its state.
Of 4 neighbours with a figure, 3 reported a larger share at or above 4 pCi/L and 1 a smaller one; the spread is 17.5% (Wayne County) to 56.7% (Lenawee County). By share, Monroe County is 21st of 82 Michigan counties with 30 or more tests for the same period.
Half the tests came in under 2.5 pCi/L and half over it; the single highest reached 151.2 pCi/L. Below the action level, 538 tests (39.1%) came in under 2 pCi/L, against 46.4% statewide, and 419 tests (30.5%) fell between 2 and 4, against 26.7% statewide.
Zone 2 on EPA's map (predicted average between 2 and 4 pCi/L) and a 30.4% share point the same way here. USGS geology rates 98% of the county's land moderate radon potential. CDC also counts 80 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 1,456 tests (2005 to 2014) to 1,375 (2008 to 2017), the share going from 29.3% to 30.4%.
Pooled shares: Radon411's sum of CDC's county counts for one period.
Monroe County, State data
Michigan's own radon test data
MeasuredWhat Michigan's own agencies publish about radon tests in Monroe 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 Monroe County
Michigan EGLE publishes its figures by ZIP code, not by county. These are the 23 ZIP codes that lie wholly or partly in Monroe County, each with the state's own figures for it. Period: About 10 years to 2026-05-15.
| ZIP code | What the state reports |
|---|---|
| 48111 | 19% greater than 4 pCi/L, median 1.8 pCi/L, 95 tests |
| 48117 | 30% greater than 4 pCi/L, median 1.9 pCi/L, 53 tests |
| 48131 | 33% greater than 4 pCi/L, median 2.8 pCi/L, 27 tests |
| 48133 | 10% greater than 4 pCi/L, median 2.8 pCi/L, 10 tests |
| 48134 | 11% greater than 4 pCi/L, median 1.3 pCi/L, 46 tests |
| 48140 | 35% greater than 4 pCi/L, median 1.4 pCi/L, 17 tests |
| 48144 | 29% greater than 4 pCi/L, median 2.6 pCi/L, 73 tests |
| 48145 | 27% greater than 4 pCi/L, median 2.6 pCi/L, 22 tests |
| 48159 | 9% greater than 4 pCi/L, median 1.7 pCi/L, 11 tests |
| 48160 | 32% greater than 4 pCi/L, median 2.7 pCi/L, 66 tests |
| 48161 | 29% greater than 4 pCi/L, median 2.3 pCi/L, 122 tests |
| 48162 | 27% greater than 4 pCi/L, median 2.5 pCi/L, 163 tests |
| 48164 | 14% greater than 4 pCi/L, median 2.0 pCi/L, 14 tests |
| 48166 | 29% greater than 4 pCi/L, median 2.6 pCi/L, 58 tests |
| 48179 | 28% greater than 4 pCi/L, median 1.4 pCi/L, 18 tests |
| 48182 | 25% greater than 4 pCi/L, median 2.0 pCi/L, 107 tests |
| 48191 | 0% greater than 4 pCi/L, median 2.0 pCi/L, 13 tests |
| 49228 | 16% greater than 4 pCi/L, median 1.7 pCi/L, 44 tests |
| 49229 | 54% greater than 4 pCi/L, median 4.9 pCi/L, 35 tests |
| 49238 | 29% greater than 4 pCi/L, median 1.7 pCi/L, 7 tests |
| 49267 | 38% greater than 4 pCi/L, median 3.1 pCi/L, 8 tests |
| 49270 | 18% greater than 4 pCi/L, median 1.8 pCi/L, 33 tests |
| 49276 | 57% greater than 4 pCi/L, median 4.7 pCi/L, 7 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.
Monroe County, Geology
The ground under Monroe County
PredictedUSGS's geologic map puts all of Monroe County's mapped land in one class: moderate radon potential. 98.3% of it lies in the area the map calls Antrim Shale-Lake deposits, to which USGS gives a radon index of 9, in the moderate band (9 to 11).
| Area | The rock, in USGS's words | Potential | Radon index | Share of land |
|---|---|---|---|---|
| Antrim Shale-Lake deposits | Antrim black shale covered by glacial lake deposits. | Moderate | 9 | 98.3% |
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 Michigan 9.6% of the land is rated high; none of Monroe County's is. Every one of the 4 counties that border it has more high-potential ground, Washtenaw County the most at 84.9%.
The map rates the ground, not the air in any home.
Local help
Monroe County, Local resources
Radon testing and mitigation in Monroe County
- Michigan Indoor Radon ProgramMichigan Indoor Radon Program, run by Michigan Department of Environment, Great Lakes, and Energy, does not license radon professionals, and answers questions about testing and mitigation in Michigan.Visit the program’s page(opens in a new tab)
- Free and low-cost kitsAsk the program whether it has free or discounted kits, or compare kits you can buy.
- Compare kits
- Professionals in Michigan69 professionals are listed in Michigan.
What Michigan's program says
- Phone
- 800-723-6642
- Radon@Michigan.gov
- Licensing of radon professionals
Michigan does not license or regulate radon testing and mitigation contractors.
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, 30.4% of the radon tests reported to CDC for Monroe County, Michigan were at or above 4 pCi/L, and the median reported pre-mitigation result was 2.5 pCi/L. Of 82 Michigan counties with 30 or more tests for the same period, 20 reported a higher share; pooled, the state comes to 26.9%.
Which counties border Monroe County?
Monroe County borders 4 counties: Washtenaw County, MI, Lucas County, OH, Wayne County, MI and Lenawee County, MI.
Products
Monroe County, Products
Testing a home in Monroe County
In Monroe County, 30.4% of 1,375 tests reported to CDC over the 2008 to 2017 laboratory totals reached 4 pCi/L, against 26.9% pooled across Michigan. In Zone 2 a short-term kit (2 to 90 days) is the quick first check in Monroe County; a long-term test tells the year-round average.
Test kits and monitors3
See every kit and monitor
Long-term kit
RL116 long-term radon test kit
- Lab fee extra
Method: Alpha track
In home: 90 days to 12 months
Monitor
RM-63Pro rechargeable radon monitor with a touchscreen
- C-NRPP 2024/25: Not included
- Battery
- Alarm
- Screen
Method: Semiconductor sensor
- See every kit and monitor Test kits and monitors
Test kits and monitors: 1 of 3
Explore
Monroe County, Bordering counties
Counties bordering Monroe County
Calculated by Radon411- Radon levels in Lenawee County, MIEPA zone 1
56.7%at or above 4 pCi/L
Median 4.6 pCi/L · 1,907 tests · 26.3 points above Monroe County
- Radon levels in Washtenaw County, MIEPA zone 1
41.3%at or above 4 pCi/L
Median 3.2 pCi/L · 8,500 tests · 10.9 points above Monroe County
- Radon levels in Lucas County, OHEPA zone 2
40.2%at or above 4 pCi/L
Median 3.0 pCi/L · 1,381 tests · 9.8 points above Monroe County
- Radon levels in Wayne County, MIEPA zone 3
17.5%at or above 4 pCi/L
Median 1.8 pCi/L · 5,594 tests · 12.9 points below Monroe County
Monroe County, Cities and towns
Cities and towns in Monroe County
The Census Bureau estimates 156,004 residents in Monroe County for July 1, 2025, 1,092 more than in 2020 (+0.7%). That works out to 284 people per square mile of land. No town dominates: Monroe, the largest, has 20,076 residents, 12.9% of the total. CDC's 1,375 reported tests for 2008 to 2017 work out to 8.8 per 1,000 residents (2025 estimate), close to Michigan's 11.3.
From Monroe to Estral Beach, CDC publishes no figure by town: each reads Monroe County's.
| Place | Residents | Since 2020 | Share of residents |
|---|---|---|---|
| Monroe | 20,076 | −1.8% | 12.9% |
| Flat Rockextends beyond Monroe County | 10,218 | −2.7% | Counted whole |
| Dundee | 6,008 | +11.5% | 3.9% |
| Milanextends beyond Monroe County | 5,973 | −1.6% | Counted whole |
| Carleton | 2,302 | −1.3% | 1.5% |
| South Rockwood | 1,576 | −1.1% | 1.0% |
| Luna Pier | 1,351 | −1.9% | 0.9% |
| Petersburg | 1,152 | −1.3% | 0.7% |
| Maybee | 578 | +5.9% | 0.4% |
| Estral Beach | 413 | −1.2% | 0.3% |
10 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 Monroe County is counted whole, so it has no share.
Monroe County, Homes
Homes in Monroe County
Monroe County is a place of houses on their own lots: 78% of its 66,300 homes are detached single-family houses, against 72% across Michigan. Half of its homes were built before 1973, close to Michigan's 1972: 35% date from before 1960 and 20% from 2000 or later. Owners live in 81% of the occupied homes (Michigan: 73%), so for most households a test and a fix are their own to order.
| Homes | Monroe County | Michigan |
|---|---|---|
| Housing units | 66,300 | 4,599,683 |
| Detached houses | 78% | 72% |
| In buildings of 5 or more | 9% | 13% |
| Mobile homes | 8% | 5% |
| Built before 1960 | 35% | 36% |
| Built since 2000 | 20% | 15% |
| Middle year built | 1973 | 1972 |
| Owner-occupied | 81% | 73% |
Census Bureau, American Community Survey, 2019 to 2023: estimates from a sample of homes, looser for a small place. Shares by Radon411.