The Agent's Guide to Radon in Southeast Michigan

What Is Radon and Why Does It Matter?

Radon is a naturally occurring radioactive gas that forms from the decay of uranium in soil and rock. It seeps into homes through cracks in the foundation, gaps around pipes, sump pits, and any opening where the house meets the ground. It's colorless, odorless, and tasteless — impossible to detect without testing.

The health risk is significant. Radon is the leading cause of lung cancer among non-smokers and the second leading cause overall, behind smoking. The EPA estimates radon causes approximately 21,000 lung cancer deaths annually in the United States. The risk increases with concentration level and duration of exposure.

Southeast Michigan Radon Levels by County

Michigan is divided into three EPA radon zones. Most of Southeast Michigan falls in Zone 2 (moderate risk), with some areas in Zone 1 (highest risk). Here's what the data shows for the counties where most of your transactions happen:

Washtenaw, Livingston, and Lapeer Counties generally show higher risk than the tri-county area, falling into EPA Zone 1. If you work in those markets, radon testing is even more critical.

What the Numbers Mean

Radon is measured in picocuries per liter (pCi/L). The EPA has established clear action levels, but understanding the nuance helps you advise clients more effectively:

How to Talk to Clients About Radon

Radon can alarm buyers unnecessarily if not framed properly. Here's how experienced agents handle the conversation:

• Before the test: "Radon testing is standard in Michigan. About 1 in 4 homes test above the action level. If it comes back high, it's fixable — not a deal-breaker."
• If results are low: "Great news — the home tested well below the EPA action level. One less thing to worry about."
• If results are elevated: "The radon level came back above 4 pCi/L, which means the EPA recommends a mitigation system. The good news: these systems are very effective and we can negotiate the installation as part of the transaction."
• If the client panics: "This doesn't mean the home is unsafe to enter or live in short-term. Radon risk is about long-term exposure over years. A mitigation system brings levels down dramatically — typically below 2 pCi/L — and can be installed in a day or two."

What Clients Need to Know About Fixing It

If radon testing reveals elevated levels, the fix is straightforward and effective. Understanding the basics helps you keep deals on track when clients hear "radon" and get nervous.

• How it works: A sub-slab depressurization system is the most common method. A pipe is installed through the basement floor into the gravel beneath, connected to a fan that draws radon gas from under the house and vents it above the roofline where it disperses harmlessly
• Installation time: Typically completed in a single day, sometimes half a day for straightforward installations
• Effectiveness: Properly installed systems typically reduce radon levels by 80-99%, often bringing levels well below 2 pCi/L
• Ongoing maintenance: Minimal — the fan runs continuously and lasts 5-10+ years. The system includes a visual indicator showing whether it's working. Periodic re-testing every 2-3 years is recommended
• Who installs: Licensed radon mitigation contractors. Michigan EGLE maintains a list of certified professionals

How Radon Affects the Deal

Elevated radon rarely kills a transaction. It's one of the most negotiable inspection findings because the fix is well-understood, effective, and relatively affordable. Here's how it typically plays out:

• Most common outcome: Seller installs a mitigation system before closing, or provides a credit for the buyer to do so
• Negotiation leverage: Unlike a roof replacement or foundation repair, radon mitigation is a known quantity — the scope and cost don't vary wildly, which makes negotiations cleaner
• Re-testing after mitigation: A post-mitigation test is recommended to confirm levels have dropped below 4 pCi/L. This usually happens 24-48 hours after installation
• Disclosure: Michigan does not currently require sellers to disclose known radon levels, but many listing agents proactively test and disclose as a good faith practice

How Radon Testing Works

Understanding the testing process helps you set expectations with clients and avoid scheduling confusion:

• Test duration: Short-term tests (used in most real estate transactions) take 48-96 hours. The testing device is placed in the lowest livable level of the home
• Closed-house conditions: Windows and exterior doors must remain closed for 12 hours before and during the test (normal entry/exit is fine). This is critical for accurate results
• Placement: The device is placed in the lowest level that could be used as living space — typically the basement, even if it's unfinished
• Timing within inspection: Radon testing can be set up at the start of the inspection and picked up 48+ hours later, or done as a separate appointment
• Seasonal variation: Radon levels tend to be higher in winter (sealed homes, heating drawing soil gas upward) and lower in summer (open windows, natural ventilation). Winter test results are generally considered worst-case

Agent's Radon Cheat Sheet

• Always recommend testing — on every purchase, regardless of county, home age, or construction type
• 1 in 4 Michigan homes test above the EPA action level of 4 pCi/L
• Oakland County is highest risk in the tri-county area at ~30% elevated
• It's fixable — mitigation systems are effective, installed in a day, and bring levels down dramatically
• It rarely kills deals — negotiation is straightforward because the fix is well-defined
• Listing agents: proactive testing before listing removes a negotiation point and builds buyer confidence
• Re-test every 2-3 years — levels can change over time as foundations settle and soil conditions shift
• No safe level exists — the EPA's 4 pCi/L is an action level, not a safety threshold