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Ten questions about radon, a cancer-causing gas found in one in four homes in Michigan

January is Radon Action Month in Michigan, when Michiganders are encouraged to learn more about this environmental hazard and test their homes during the heating season.

EGLE staffers Nicolas Luciani (l) and Les Smith at EGLE radon booth.

EGLE staffers Nicolas Luciani (l) and Leslie E. Smith III at EGLE radon booth.


Radon is a naturally occurring radioactive gas. You cannot see, smell or taste radon, and there are no short-term side effects that could cause alarm or warn of its presence. However, long-term exposure to radon increases the risk of developing lung cancer, which accounts for more deaths in both men and women than any other form of cancer in the United States, according to the Michigan Department of Environment, Great Lakes, and Energy (EGLE), which aims to:

  • increase awareness of health risks associated with elevated indoor radon levels,
  • promote home testing, and
  • encourage citizens to take action to reduce exposure once elevated radon levels are found.

Behind smoking, radon is the second leading cause of lung cancer and considered a leading environmental cause of cancer deaths in the United States.

The U.S. Environmental Protection Agency estimates that radon is responsible for about 21,000 lung cancer deaths in the United States each year.

Leslie E. Smith, III is EGLE’s indoor radon specialist. Throughout the year, he gets questions about radon gas. Here are 10 common questions and answers about radon.

Is radon really a health risk? I've heard it is a scam.

Yes, radon really is a health risk. Radon is a Class A carcinogen, which means it is known to cause cancer in humans. It is the second leading cause of lung cancer after smoking, and results in approximately 21,000 lung cancer deaths in the United States each year. Not everyone who breathes radon will develop lung cancer. Your risk is determined by such things as how much radon is in your home (and/or workplace, school, or other indoor environment); the amount of time you spend in your home (and/or workplace, school, or other indoor environment); and whether you smoke or have ever smoked. The longer you are exposed, and the higher the radon level, the greater the risk.

How do I know if I have a radon problem in my home? What radon level is safe?

The only way to know whether your home has elevated radon levels is to test your home. There are no physical signs to warn you of the presence of radon, and it cannot be detected with the senses. Radon levels can vary significantly from home to home, and you cannot use your neighbor's test results to determine whether or not your home has a problem. Your home must be tested.

There is no "safe" radon level. There is some risk associated with any exposure, and generally, the higher the radon level and the longer the exposure, the greater the risk.

Congress has a set a long-term goal of reducing indoor radon levels so that they are no greater than exposure to ambient (outdoor) air. The average outdoor level is between 0.3 picocuries per liter (pCi/L) and 0.7 pCi/L, and while that level is not yet technologically achievable, many homes can be brought down to levels below 2 pCi/L. In the meantime, we are using a guideline of 4 pCi/L. This guideline was selected because the rule of thumb is to keep exposure to radiation as low as reasonably achievable (ALARA), and 4 pCi/L is a reasonably achievable radon level. Whether a home has 100 pCi/L, or 50 pCi/L, or 20 or 10 pCi/L, the current technology can bring the level down to below 4 pCi/L for a reasonable amount of money, with a reasonable amount of effort, over a reasonable period of time.

How does radon get into my home?

Radon enters homes through openings in the foundation floor or walls, wherever the foundation is in contact with the soil. Because radon is a gas, it can travel through the soil, and it generally moves from an area of higher pressure to one of lower pressure. In most cases, the soil is at higher pressure than the house, and if radon is traveling along the foundation, it can be pushed into the lower pressure area through openings such as sump crocks, crawlspaces, space around plumbing or wiring, floor/wall joints, cracks, hollow block walls, or other entry points. Ultimately, tiny or large openings in the foundation floor or walls can act as entry points, and the pressure difference between the soil and the house acts as the driving force that allows radon to enter your home.

My home is new, old, drafty, or energy-efficient and built on a slab, crawlspace, basement, walk-out basement, or has multiple foundations. Do I need to worry?

Any home, regardless of age, energy-efficiency, or foundation type, could have a radon problem. The only way to know whether or not a particular home has a problem is to test THAT home.

Where can I get a radon test kit? Who can test my home?

Radon test kits are available from your local health department or they can be purchased at some hardware stores, home improvement centers, or other retail outlets. Radon test kits can also be purchased on the internet. If you need a professional tester to help you test your home or a home you're considering purchasing, use an individual who is certified by the National Radon Proficiency Program or the National Radon Safety Board.

How much does it cost to test?

Most short-term do-it-yourself radon test kits cost between $10 and $20, and long-term kits generally cost between $20 and $50. The kits sold by the local health departments include the price of the test device, the postage to mail it back to a lab out of state, and the lab fees for having the device analyzed. Most radon test kits sold in retail stores or through mail order also include everything in the price, but a few companies charge extra for postage or lab analysis, so be sure you know what you're getting before you make the purchase!

People involved in real estate transactions often prefer to have a professional perform the measurement for them. Test prices vary depending on the device or instrumentation used by the tester, travel costs, and so on, but the price would generally range from $50 to $150. Be sure the tester you hire understands and follows the testing protocol. (Testers are not licensed in Michigan, but you are encouraged to use an individual certified by either the National Radon Proficiency Program or the National Radon Safety Board. Contact your local health department for a list of measurement companies or visit the organization websites.)

I forgot to use my radon test last year. Can I still use it?

Radon test kits do expire and have an expiration date on the top right corner of the test kit. If it's past the expiration date, you will need to get a new test kit to be assured that you can get an accurate measurement.  Radon test kits are available from your local health department.

My neighbor tested and didn't find a radon problem. Do I still need to test?

Yes! Radon levels can vary significantly from home to home or land parcel to land parcel. The only way to know whether your home has a radon problem is to test your home.

If I find a radon problem, what next? Can it be fixed? Who does this kind of work? What does it cost? What do they do to fix a radon problem?

Elevated radon levels can be reduced, but first you should confirm that you really have a problem by conducting follow-up measurements. When a problem has been confirmed, you may want to hire a professional radon mitigation contractor to help you reduce the levels. Radon mitigation contractors are not licensed in Michigan.  So, you are encouraged to use an person who is certified by the National Radon Proficiency Program or the National Radon Safety Board.

Occasionally, when radon levels are fairly close to the guideline of 4 picocuries per liter (4 pCi/L), caulking and sealing radon entry points may be enough to bring the radon down to acceptable levels. However, caulking and sealing alone does not always provide the reduction you need, and it is seldom a long-term solution to a real radon problem. In most cases, a professional contractor would install a radon mitigation system and provide a guarantee of levels below 4 pCi/L. There are other methods, but a radon mitigation system is the most common technique used in Michigan. A radon mitigation system uses a vent pipe and fans to remove radon vapors from under your foundation and exhaust them above the roof where it's safe, ensuring the radon never enters your home.  Check out this short video showing how a mitigation system works.

The cost of a radon mitigation system in Michigan can vary significantly depending on where you are in the state and who you hire. A typical range in price would be $800-$1,500.

I'm buying a new home and the inspector found radon. What do I do now? Should I walk away from the deal?

Radon levels can almost always be reduced, so if you like a home, you should buy it. Radon is not a good reason to walk away from the deal. The issue is negotiable between the buyer and the seller, and there are a lot of options to consider. For instance, the buyer may ask that the seller fix the problem, or the buyer may choose to take the house "as is" and fix it later when it's more convenient. The two parties may come up with some formula for sharing the costs, or the seller may put money in escrow, so the buyer can retest to determine the annual average. In any event, the problem is fixable and shouldn't be a deal-breaker.

For more information about radon testing and mitigation, including resources for homeowners, builders, realtors, teachers and healthcare providers, go to, or call EGLE's Indoor Radon hotline at 800-RADONGAS or 800-723-6642.

Learn more about radon and other radiological materials in Michigan in EGLE Classroom’s January 18 EnviroSchool webinar for educators, Radioactive Michigan.

Stay informed by signing up for the GovDelivery list for Michigan Indoor Radon Program updates. Subscribers will be updated on items of general interest related to indoor radon testing and mitigation in Michigan. These updates may include announcements of state or national radon outreach events, radon testing and mitigation tips or reminders, or updates to radon resources.