Locations and reports
Radon Levels in Washtenaw County, Michigan
What this means for you
- Your area: EPA rates Washtenaw County Zone 1, the highest of its three radon zones. That is a prediction for the whole county, and homes with elevated levels occur in all three zones.
- Local tests: Of 8,500 radon tests reported to CDC for Washtenaw County (2008 to 2017), 41.3% were at or above 4 pCi/L, EPA's action level.
- Your home: The only way to know your home’s level is to test it.
pCi/L (picocuries per liter) is the unit radon is measured in. EPA recommends fixing a home at 4 pCi/L or above, its action level.
Over the 2008 to 2017 laboratory totals, 41.3% of the radon tests reported to CDC for Washtenaw County, Michigan came back at or above the EPA action level of 4 pCi/L, and the median result was 3.2 pCi/L. EPA's Map of Radon Zones places the county in Zone 1, highest predicted potential. Radon levels vary from home to home, so only a test measures the level in yours.
Predicted: EPA radon zone
EPA Zone 1: highest predicted potential
EPA predicts an average indoor of greater than 4 pCi/L (greater than 150 Bq/m³) across the county as a whole.
This is a county-level geologic prediction. It is not a measurement of any address, and houses with elevated radon are found in all three zones.
USGS geologic potential: Low across 85% of the county's land area
Predicted: EPA Map of Radon Zones
Measured: tests reported to CDC
Radon tests reported for Washtenaw County, 2008 to 2017, laboratory
- Tests reported
- 8,500
- At or above 4 pCi/L
- 41.3%
- Median result
- 3.2 pCi/L
Of 8,500 pre-mitigation tests reported to CDC, not homes in this area. CDC publishes the share in each band, not a count per band, so the per-band counts in the table are calculated by Radon411 and rounded to add up to the published total.
| Result band | Tests Calculated by Radon411 | Share Measured |
|---|---|---|
| Under 2 pCi/L | 2,780 | 32.7% |
| 2 to 4 pCi/L | 2,210 | 26.0% |
| 4 pCi/L and above | 3,510 | 41.3% |
Distribution of tested buildings, not this house. People testing before a sale, or because they suspect a problem, are over-represented in any reported testing data.
Measured: CDC tracking data. Figure above: 2008 to 2017, laboratory. Measured data period: 2005 to 2017 (every CDC figure on file).
Washtenaw County, In figures
Washtenaw County in figures
What the published data says about Washtenaw County, in words. A zone and a share of tests describe an area, never the level in any one home.
Predicted
PredictedEPA places Washtenaw County in Zone 1, highest predicted potential, as it does 8 other counties of Michigan's 83.
Of the 6 bordering counties, EPA places Jackson County and Lenawee County in Zone 1, Livingston County, Monroe County and Oakland County in Zone 2 and Wayne County in Zone 3.
Reported tests
MeasuredCDC publishes no annual figure for Washtenaw County; its figure is a laboratory total for 2008 to 2017: 41.3% of 8,500 reported tests were at or above 4 pCi/L.
Local record
Michigan's radon program is the Michigan Indoor Radon Program, run by Michigan Department of Environment, Great Lakes, and Energy; its contacts are under Local resources.
The county's largest incorporated places are Ann Arbor, Ypsilanti and Saline; the figures here cover them as part of the county.
Washtenaw County, State data
Michigan's own radon test data
MeasuredWhat Michigan's own agencies publish about radon tests in Washtenaw County, with their period. These are not CDC's figures and are never added to them.
What Michigan EGLE reports for the ZIP codes in Washtenaw County
Michigan EGLE publishes its figures by ZIP code, not by county. These are the 25 ZIP codes that lie wholly or partly in Washtenaw County, each with the state's own figures for it. Period: About 10 years to 2026-05-15.
| ZIP code | What the state reports |
|---|---|
| 48103 | 37% greater than 4 pCi/L, median 2.9 pCi/L, 1,229 tests |
| 48104 | 34% greater than 4 pCi/L, median 2.7 pCi/L, 454 tests |
| 48105 | 38% greater than 4 pCi/L, median 2.9 pCi/L, 538 tests |
| 48108 | 25% greater than 4 pCi/L, median 1.9 pCi/L, 302 tests |
| 48111 | 19% greater than 4 pCi/L, median 1.8 pCi/L, 95 tests |
| 48118 | 48% greater than 4 pCi/L, median 3.8 pCi/L, 253 tests |
| 48130 | 49% greater than 4 pCi/L, median 3.8 pCi/L, 339 tests |
| 48137 | 50% greater than 4 pCi/L, median 4.0 pCi/L, 68 tests |
| 48158 | 62% greater than 4 pCi/L, median 5.5 pCi/L, 138 tests |
| 48160 | 32% greater than 4 pCi/L, median 2.7 pCi/L, 66 tests |
| 48167 | 39% greater than 4 pCi/L, median 3.1 pCi/L, 182 tests |
| 48168 | 29% greater than 4 pCi/L, median 2.2 pCi/L, 159 tests |
| 48169 | 45% greater than 4 pCi/L, median 3.4 pCi/L, 390 tests |
| 48170 | 23% greater than 4 pCi/L, median 2.3 pCi/L, 203 tests |
| 48176 | 43% greater than 4 pCi/L, median 3.2 pCi/L, 351 tests |
| 48178 | 31% greater than 4 pCi/L, median 2.4 pCi/L, 372 tests |
| 48189 | 51% greater than 4 pCi/L, median 4.0 pCi/L, 146 tests |
| 48191 | 0% greater than 4 pCi/L, median 2.0 pCi/L, 13 tests |
| 48197 | 28% greater than 4 pCi/L, median 2.4 pCi/L, 473 tests |
| 48198 | 22% greater than 4 pCi/L, median 2.1 pCi/L, 202 tests |
| 49229 | 54% greater than 4 pCi/L, median 4.9 pCi/L, 35 tests |
| 49236 | 69% greater than 4 pCi/L, median 6.0 pCi/L, 54 tests |
| 49240 | 47% greater than 4 pCi/L, median 3.2 pCi/L, 59 tests |
| 49285 | 53% greater than 4 pCi/L, median 4.2 pCi/L, 17 tests |
| 49287 | 52% greater than 4 pCi/L, median 4.4 pCi/L, 27 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.
Washtenaw County, Comparison
How Washtenaw County compares
MeasuredWashtenaw County's own published CDC figures beside those of the counties that border it, for the same period.
Share of reported tests at or above 4 pCi/L
Measured2008 to 2017, laboratory, highest first. Each county’s own published CDC figure.
- Lenawee CountyMI1,907 tests56.7%
- Jackson CountyMI2,964 tests49.7%
- Livingston CountyMI4,885 tests43.1%
- Washtenaw CountyThis page8,500 tests41.3%
- Monroe CountyMI1,375 tests30.4%
- Oakland CountyMI16,224 tests28.8%
- Wayne CountyMI5,594 tests17.5%
Median reported result
Measured2008 to 2017, laboratory, highest first. Each county’s own published CDC figure.
- Lenawee CountyMI1,907 tests4.6 pCi/L
- Jackson CountyMI2,964 tests3.9 pCi/L
- Livingston CountyMI4,885 tests3.4 pCi/L
- Washtenaw CountyThis page8,500 tests3.2 pCi/L
- Monroe CountyMI1,375 tests2.5 pCi/L
- Oakland CountyMI16,224 tests2.3 pCi/L
- Wayne CountyMI5,594 tests1.8 pCi/L
Each figure is that county’s own published CDC figure for 2008 to 2017, laboratory, counting radon tests reported to CDC, not homes. Washtenaw County is this page. Nothing is averaged or combined across counties. The test count beside each county is CDC’s published number of pre-mitigation tests behind its figures. Figures from few tests can swing widely from year to year. Every Michigan county’s own figure is in the Michigan county table.
CDC publishes this figure only for counties here, so there is no state or national number to compare Washtenaw County, Michigan with.
Washtenaw County, Bordering counties
Counties bordering Washtenaw County
Calculated by Radon4116 counties share a boundary with Washtenaw County, computed from Census county geometry. Radon potential follows geology rather than county lines, so a bordering county’s report can be worth reading alongside this one.
- Lenawee CountyMIZone 1: Highest predicted potential
- Monroe CountyMIZone 2: Moderate predicted potential
- Wayne CountyMIZone 3: Lower predicted potential
- Jackson CountyMIZone 1: Highest predicted potential
- Livingston CountyMIZone 2: Moderate predicted potential
- Oakland CountyMIZone 2: Moderate predicted potential
Washtenaw County, Local resources
Local resources in Michigan
Who to ask in Michigan: the state's radon program, test kits and professionals.
Michigan Indoor Radon Program
Michigan Department of Environment, Great Lakes, and Energy
Michigan’s radon program answers questions about testing, mitigation and the rules where you live.
- Phone
- 800-723-6642
- Radon@Michigan.gov
- Licensing of radon professionals
Michigan does not license or regulate radon testing and mitigation contractors.
Test kits
Ask the program whether it has free or discounted kits, or compare kits you can buy.
Radon professionals
6 professionals are listed in Michigan.
Professionals in MichiganWashtenaw County, Cities and towns
Cities and towns in Washtenaw County
The radon figures on this page are for Washtenaw County as a whole. They do not differ by city or town.
- Ypsilanti
- Saline
- Milan (part)
- Chelsea
- Dexter
- Manchester
- Barton Hills
8 incorporated places, as listed in the U.S. Census Bureau’s 2020 place reference files. “(part)” marks a place that extends into another county.
Washtenaw County, Questions
Questions about radon in Washtenaw County
Common questions8 questions, answered from the figures above
How do I get a radon test in Washtenaw County?
EPA says you can test your home yourself or hire a qualified radon test company, and that either approach takes only a small amount of time and effort. No certified tester listed on Radon411 names Washtenaw County as a service area yet. The Michigan radon program is the place to ask about certified testers and any test kit offer it runs.
How to test a homeTest kits comparedFree and low-cost kits by stateMichigan radon program
Are radon levels high in Washtenaw County?
In 2017, 41.3% of the radon tests reported to CDC for Washtenaw County, Michigan were at or above 4 pCi/L, and the median reported pre-mitigation result was 3.2 pCi/L. That is a share of reported tests, not of homes. EPA places Washtenaw County in Zone 1, highest predicted potential, a predicted average indoor screening level greater than 4 pCi/L. Homes with elevated levels occur in all three zones, so the figures describe the area, not your house. Testing is the only way to know the radon level in a specific building.
Who does radon mitigation in Washtenaw County?
No listed mitigator names Washtenaw County as a service area yet; the Michigan directory lists 6 companies. EPA recommends having a qualified contractor fix a home with a radon problem, because lowering high radon levels takes technical knowledge and special skills, and some states require the work to be done by a licensed or certified professional. Your state radon program is the place to check whether Michigan requires one.
How radon mitigation worksWhat mitigation costsMitigators in Michigan
What EPA radon zone is Washtenaw County in?
EPA places Washtenaw County, Michigan in Zone 1, which EPA describes as highest predicted potential for the area. A zone is a prediction for the whole county and never determines whether a particular home should be tested. EPA recommends testing every home regardless of zone.
Should I test my home in Washtenaw County?
Yes. Testing is the only way to know the radon level in a specific building. EPA recommends fixing a home when the radon level is 4 pCi/L or higher. EPA recommends considering a fix when the level is between 2 and 4 pCi/L. How to test a home.
When is the best time of year to test?
EPA says short-term tests stay in the home from 2 to 90 days and that all radon tests should run a minimum of 48 hours; long-term tests stay more than 90 days. EPA's guides do not name a best season: they say radon levels tend to vary from day to day and season to season, so a long-term test is more likely than a short-term test to tell you the year-round average.
What does it cost to test?
EPA's Citizen's Guide calls testing easy and inexpensive, and EPA's Home Buyer's and Seller's Guide says passive short-term and long-term devices are generally inexpensive, while active devices may cost more. No national average price is published for this, so Radon411 does not give one. What testing costs.
Which counties border Washtenaw County?
Washtenaw County borders 6 counties, derived from Census county geometry. Radon potential follows geology rather than county lines, so a bordering county's report can be relevant.
What these figures mean if you own, buy, sell or rent
The reported-test figures on this page describe Washtenaw County, Michigan in 2017. They describe tests other people carried out in other buildings, and none of them measures yours.
- How to test a home
If you own your home
Test the lowest lived-in level; a short-term kit screens in days, a long-term kit reflects the year.
- Buying a house: radon guide
If you are buying
Ask for past results and any system's post-mitigation test, and test during the sale.
- Selling a house: radon guide
If you are selling
Testing before you list puts the timing in your hands; disclosure rules differ by state.
- Radon in rental homes
If you rent, or rent out a home
A tenant can test; a fix is the owner's to make, and duties differ by state.
How long a test has to run, under what conditions, and what EPA says a result means: the testing standard, in full.
Washtenaw County, Products
Testing and mitigation products
Whatever the figures for Washtenaw County show, only a test tells you about one home.
Testing
- Short-term test kitsPassive detectors exposed for a few days under closed-building conditions, then analyzed by a lab.
- Long-term test kitsDetectors exposed for more than 90 days, for a closer picture of the annual average.
- Continuous monitorsPowered devices that log radon on a repeating cycle, often used for transaction tests.
- Digital detectorsConsumer devices that display a running radon reading without a lab.
- Water radon testsKits for radon dissolved in well water, analyzed by a lab.
Mitigation
- Mitigation fansThe inline fan that keeps a soil depressurization system running, sized by the installer.
- System indicatorsU-tube manometers and fan alarms that show whether a mitigation system is still working.
- Sealing materialsCrack, joint and sump sealing used alongside a mitigation system, not instead of one.
Washtenaw County / Next steps
What to do next
Learn
Know what radon is
What radon is, how it gets indoors, and why a county zone is not a reading for your home.
Learn about radonTest
Test the building you live in
Short-term or long-term, where the device goes, and closed-house conditions.
How to testFix
Bring a high level down
How a mitigation system works, and the retest that confirms it.
How mitigation worksFind a pro
Hire a certified professional
Measurement and mitigation professionals by state, with their certifications.
Find a professional
Informational. Follow EPA guidance. EPA says all radon tests should be taken for a minimum of 48 hours, with windows and doors closed from 12 hours before a short-term test.