If you're buying a home in Macomb County, Michigan — Sterling Heights, Warren, Clinton Township, Shelby Township, Macomb Township, or anywhere up the Gratiot corridor — radon should be on your inspection checklist. Macomb gets less attention than Oakland County in radon conversations, but the data tells a more complicated story than the EPA's zone map suggests. This guide walks you through everything a Macomb County buyer needs to know: what radon is, what your zone designation actually means, how testing works during your inspection, what the results mean, and what mitigation costs in 2026.
Radon is a colorless, odorless, tasteless radioactive gas produced by the natural decay of uranium in soil and rock. It seeps up through the ground and accumulates in enclosed indoor spaces — basements, crawl spaces, slab-on-grade ground floors. Outdoors it dissipates harmlessly in the open air. Indoors, with a tight building envelope and a stack effect pulling air upward, it can build to levels that materially raise lifetime cancer risk.
According to the EPA, long-term exposure to elevated indoor radon is the leading cause of lung cancer among non-smokers in the United States and the second-leading cause overall after smoking. Because the gas produces no symptoms in the short term, the only way to know whether a home has a problem is to test for it. The EPA's action level — the threshold at which mitigation is recommended — is 4.0 picocuries per liter (pCi/L).
Macomb County is split between EPA Radon Zone 2 (moderate potential, predicted average 2–4 pCi/L) and Zone 3 (low potential, predicted average below 2 pCi/L) depending on the specific township. The county sits at a geological transition: northern and western Macomb (Romeo, Washington Township, Bruce Township, parts of Shelby) tend to track closer to Oakland County's elevated Zone 1 levels, while southern Macomb (Warren, Eastpointe, parts of St. Clair Shores) sit in Zone 3 territory closer to Lake St. Clair.
Three factors make Macomb County radon results harder to predict than the zone map suggests:
There are two main types of radon tests inspectors use during a real estate transaction:
A continuous radon monitor is a small electronic device that takes hourly readings for at least 48 hours, then produces a detailed report. This is the gold standard for real estate testing because it's tamper-resistant (the device records temperature, humidity, and barometric pressure changes that would indicate someone opened windows or moved the device), it produces an hourly graph that proves test conditions were correct, and the seller can't dispute the data.
A passive charcoal canister sits in the basement for 48–96 hours, then gets mailed to a lab for analysis. It's cheaper but produces a single average number with no tamper detection. We don't recommend canisters for real estate transactions — if the result is borderline or contested, you have nothing to fall back on.
We use continuous monitors for all Macomb County radon tests. Results come back within hours of test completion, not days.
Real estate radon tests must be conducted under "closed-house conditions" — windows and exterior doors closed except for normal entry/exit — for at least 12 hours before the test starts and throughout the entire test period. The test should be placed:
If a seller leaves windows open or runs the HVAC fan continuously to dilute results, a continuous monitor will catch the change in conditions and the test should be invalidated and re-run.
Once you get your result, here's how to interpret it:
If your test exceeds 4.0 pCi/L, mitigation is straightforward and effective. The standard solution is a sub-slab depressurization system: a contractor cuts a small hole in the basement slab, installs a PVC pipe down into the soil, runs the pipe up through the home (or up the exterior), and adds a continuous-running inline fan that creates negative pressure under the slab. The fan pulls radon from beneath the home and vents it harmlessly above the roof line.
Typical Macomb County mitigation pricing in 2026:
After installation, retest. A properly installed system should bring almost any home under 2.0 pCi/L. The mitigation contractor should warranty the system and the result.
If your inspection radon test comes back above 4.0 pCi/L in Macomb County, you have leverage. The most common outcomes:
Walking away over radon alone is rare in Macomb County. Mitigation is reliable, predictable, and reasonably priced. The result is more often a credit and a project for the first 60 days of homeownership.
We test for radon as a standard add-on to every Macomb County home inspection — Sterling Heights, Warren, Clinton Township, Shelby Township, Macomb Township, Romeo, and the surrounding areas. Continuous monitor, 48-hour minimum test, hourly data graph included with your inspection report. Call (734) 359-7993 or book online and we'll set the monitor at your inspection and pick it up when results are ready.