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Testing Your Home for Radon

Test your home

Testing your home is the only way to know if you and your family are at risk for radon. This is an important first step to know your home's radon level.

You can buy a radon test kit from a hardware store or a Radon Information Center for around $20. Certified radon measurement professionals are also available to test for you.

Fix your home if your radon level is 4 picocuries per liter (pCi/L) or higher. Levels below 4 pCi/L can still pose a risk, and in many cases may be reduced. Call your Wisconsin Radon Information Center for more information.


High levels of radon are dangerous to you and your family.

Having work done as soon as possible to lower the levels of radon by a certified radon mitigation contractor will protect your family.

Radon testing should be done every two years, even if levels are initially below 4 pCi/L.

Measure for at least two days

Your first radon measurement should be made for a minimum of two days in the lowest lived-in level of your home with the windows kept closed, as recommended in the United States Environmental Protection Agency's (EPA's) A Citizen's Guide to Radon.

A basement can be considered lived-in (for radon testing purposes) if it is occupied at least seven hours per week. Otherwise, the main floor is the best place to test.

The testing recommendations for real estate transactions or home sales can be somewhat different. Consult the EPA's Home Buyer's and Seller's Guide to Radon.

Understanding your radon test results

The EPA recommends performing a short-term test, two to three days, first. If that test comes back above the action level of 4 pCi/L, then a long-term test, at least 90 days and usually 6-12 months, is recommended to gauge the home's annual radon concentration. The below chart clarifies steps homeowners should take.

Test result Steps needed
Less than 4 pCi/L

No follow-up is needed as your home has low radon levels.

Test the home again after any air sealing work, heating/air conditioning system changes, or foundation modification.

Between 4-7 pCi/L

Do a long-term test to determine your average radon exposure. However, you can conduct a short-term test if quicker results is desired. Call 1-888-569-7236 to get more information about long-term testing.

Radon levels may change with seasons and are low when windows are open. The average radon level in occupied floors of your home determines your lung cancer risk from radon exposure.

8 pCi/L and above Do a follow-up short-term test immediately. If the average of the two results is greater than 4 pCi/L, you should consider fixing your home. The higher your short-term test results, the more certain it is that you should fix your home.

 Radon is measured in picocuries per liter, which are abbreviated pCi/L.

How your results compare

0.4 pCi/L: Lowest achievable level in a house and average outdoor levels.

1.8 pCi/L: Average radon level in the lowest lived-in floors of Wisconsin homes.

4 pCi/L: Level in basements of over half of homes in some regions of the state.

Testing your water

Compared to radon entering your home through the air, the risk is much lower in water. If you are concerned about radon in water, contact your local water supplier or test your private well. Refer to the Citizens Guide to Radon on EPA's website for more information, or the Radon in Water DHS webpage.


Experts are available statewide to answer your questions and provide test kits to the general public.

Have questions or need help? Get in touch with a radon expert by calling
1-888-LOW-RADON (1-888-569-7236).


Last revised May 9, 2023