Michigan · county radon data
Radon in Kent County, Michigan
16.5% of the 6,257 home radon tests on record here reached the EPA action level — mid-pack for the state, ranked #43 of 83 tested Michigan counties.
What the numbers say
Kent County sits 0.1 points below the Michigan median (16.6% of tests over the limit across the state's counties). The median reading among its 6,257 reported tests was 1.8 pCi/L — and the single highest test on record reached 76.5 pCi/L, more than 19× the action level. EPA maps place the county in Radon Zone 2 — moderate predicted potential (2–4 pCi/L average screening levels), which still produces plenty of homes over the limit.
Why: the ground under Kent County
Covered in thick glacial drift over the Michigan Basin's sedimentary rocks. Radon potential is moderate for most of the state, but tills incorporating shale or carbonate fragments can push individual homes well over the action level — testing is the only way to know. (Regional attribution here is well supported; unit-level detail is coarser — see methodology.)
Geology sources: USGS WRI 98-4169 · EPA MI zone documentation.
The housing stock factor
The median Kent County home dates to 1977 — decades before radon-resistant new construction entered building codes. With 663,150 residents largely housed in that older stock, testing is the only way any individual household knows where it stands.
ZIP codes in Kent County
Michigan doesn't publish ZIP-level test results, so these ZIPs share the county figures above — the roster is here so you can confirm your address is covered by this data.
| ZIP | Place |
|---|---|
| 49301 | Ada |
| 49302 | Alto |
| 49306 | Belmont |
| 49315 | Byron Center |
| 49316 | Caledonia |
| 49319 | Cedar Springs |
| 49321 | Comstock Park |
| 49326 | Gowen |
| 49330 | Kent City |
| 49331 | Lowell |
| 49341 | Rockford |
| 49343 | Sand Lake |
| 49345 | Sparta |
| 49418 | Grandville |
| 49503 | Grand Rapids |
| 49504 | Grand Rapids |
| 49505 | Grand Rapids |
| 49506 | Grand Rapids |
| 49507 | Grand Rapids |
| 49508 | Grand Rapids |
| 49509 | Wyoming |
| 49512 | Grand Rapids |
| 49519 | Wyoming |
| 49525 | Grand Rapids |
| 49544 | Grand Rapids |
| 49546 | Grand Rapids |
| 49548 | Grand Rapids |
Kent County in the Michigan picture
| Kent County | 16.5% over the limit | 6,257 tests |
| Michigan's highest: Lenawee County | 56.7% | 1,349 tests |
| Michigan county median | 16.6% | 83 counties ranked |
| Share of all Michigan tests from this county | 7.6% | |
Ranked nearby in Michigan
- Gratiot County — #40, 16.8% of 327 tests over the limit
- Ottawa County — #41, 16.8% of 1,957 tests over the limit
- Sanilac County — #42, 16.6% of 264 tests over the limit
- Manistee County — #44, 16.5% of 286 tests over the limit
- Alger County — #45, 16.4% of 118 tests over the limit
- Isabella County — #46, 16.4% of 568 tests over the limit
(Ranking neighbors — counties adjacent in the Michigan test ranking, not necessarily on the map.)
High test? Fixes and real pricing: the Michigan mitigation cost guide. Every statistic here traces to the methodology (CDC EPHT (labs), 2008–2017; zones: EPA; year built & population: ACS 5-year).
Kent County radon FAQ
- Is radon high in Kent County?
- 16.5% of 6,257 home tests reported to the CDC came back at or above the EPA action level of 4 pCi/L — 0.1 points below the Michigan county median of 16.6%, ranking #43 of 83 tested counties. EPA classifies the county as Zone 2.
- Does an older home in Kent County mean more radon risk?
- The county's median home was built in 1977 — before radon-resistant construction practices entered building codes in the 1990s, so most of the housing stock has no built-in radon protection. Construction age changes the odds, not the answer: only a test tells you about your house.
- Where do these Kent County numbers come from?
- 6,257 aggregated home tests in the CDC's Environmental Public Health Tracking dataset (CDC EPHT 2008-2017). Median reading: 1.8 pCi/L; the highest recorded test hit 76.5 pCi/L. How we handle the data, including its limits, is documented on our methodology page.
- What's the highest radon reading recorded in Kent County?
- 76.5 pCi/L — 19× the EPA action level — against a county median of 1.8 pCi/L across 6,257 tests. That spread is the point: neighboring homes routinely test wildly differently.