Testing Your Home for Radon

Testing Your Home

You can buy a radon test kits from hardware stores or a Radon Information Center for around $20; certified radon measurement professionals are also available to test for you.

  1. Your first radon measurement should be made for a few days (two days, minimum) 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.
  2. A basement can be considered lived-in (for radon testing purposes) if it is occupied at least 7 hours per week. Otherwise, the main floor is the best place to test or do a follow-up test.*

*Note: 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

Radon is measured in picoCuries per liter, which are abbreviated pCi/L. Use the table below to understand what to do based your your test results.

Test Result Action
First result less than 4 pCi/L: No follow-up needed. Your home has low radon levels.
First result between 4 and 8 pCi/L: Do a year-long follow-up measurement with an alpha-track detector to determine your average radon exposure. 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.  Call 1-800-RADON to get more information about long-term testing.
First result above 8 pCi/L: Do a short-term or long-term follow-up test to confirm the accuracy of your first result.


If follow-up measurements indicate your radon exposure is higher than 4 pCi/L (the U.S. EPA guideline), it can be significantly reduced. The higher your confirmed radon results are, the more important it is to fix your home.

  • Outdoor air has about 0.4 pCi/L, and this is the lowest achievable level in a house.
  • The average radon level in the lowest lived-in floors of homes in Wisconsin is about 1.8 pCi/L.
  • In Wisconsin, 25 percent of homes have radon at over 4 pCi/L in basements.
  • In some regions of the state, more than half the homes have radon at over 4 pCi/L in basements.

How Soon to Fix Your Home

High levels of radon are dangerous to you and your family. When follow-up radon measurements on occupied levels of your home are high, you should get estimates on radon mitigation work (work to lower the levels of radon) by professionals included on the list of certified radon mitigation contractors. Having this work done will protect your family, and it will increase the value of your house.

If radon test results in occupied levels of your home are 4 to 20 pCi/L, it could take up to a year to get the work done. For test results above 20 pCi/L, it's important to get the work done soon as soon as possible.  Call your Wisconsin Radon Information Center for more information.

Last Revised: November 28, 2016