Some radon testing, including testing related to legal transactions, should be performed by a professional radon contractor, while other radon testing can be done by the occupants of a home. You can test your home for radon using a short-term radon test kit. Using a short-term radon test is easy, and the following guidelines will help ensure the best results.

Before Radon Testing

Read the manufacturer's instructions for testing that are included in the test kit.

Except for normal use, keep the home’s doors and windows closed for 12 hours before beginning the short-term radon test. Try to avoid having windows or doors open for prolonged periods of time during testing, and notify all occupants of the importance of keeping them closed while radon testing is in progress.

When It Is Time for Testing

The lowest occupied level of the home should be tested for radon. Select a location for the radon test that is: 

  • 3 feet away from exterior door and windows.
  • 20 inches above the floor.
  • At least 1 foot below the ceiling
  • 4 inches away from other objects on the surface where you are placing the test.

Avoid testing places that may be damp, like a laundry room or bathroom.

The test should not be placed directly above or below a HVAC vent.

Place the radon test paper side up, and record the starting time of the test.

After Testing

At the end of the testing period (typically 3 days), record the ending time, seal up the test and information in the envelope provided, and mail it back to the laboratory as soon as possible. A pre-paid shipping label is included, but the sample must be put in the mail promptly to help ensure it reaches the lab within the designated timeframe.

When you receive the test results, the radon level will be given in picocuries per liter.

If the home has 2 picocuries or less, that is pretty low.

If the level is higher than 2 picocuries, do another test to confirm the radon level.

If the second test result is over 4 picocuries, take action to lower the radon levels in the home.

Lowering Indoor Radon Levels

Radon mitigation is the process of lowering the radon levels in a home or building. An expert will evaluate the building to determine the most appropriate ways to address radon in your home. The cost of a radon mitigation system in Missouri is typically $2,000 or less for a 2,000 square foot home. A link to a searchable listing of Missouri radon contractors certified by the National Radon Proficiency Program (NRPP) can be found on nrpp.info/pro-search. More information on radon mitigation can be found in the EPA’s Consumer’s Guide to Radon Reduction.

Radon Testing Video