How to Test Your Home for Radon

Step-by-step instructions on how to test your home for radon.

How to use a short-term test

Step 1: Place the test kit in the lowest living level of your home

This may be a bedroom, living room, office, playroom or den, the basement if it is frequently used, or the first floor. The test should be at least three feet from an exterior wall, one foot from an interior wall and 20 inches above the floor in a location where it won’t be disturbed – away from drafts, high heat, high humidity, and exterior walls. Do not put the test in your bathroom or kitchen.

Step 2: Close your windows and exterior doors

Close them for at least 12 hours before beginning the test. Keep windows and doors closed as much as possible during the test. Leave the kit in place for 48 to 72 hours. Depending on the test kit purchased, kits exposed for less than 2 days or more than 7 days are invalid.

NOTE: It is recommended to start the test on Friday morning and drop it off at the post office on Monday morning. Waiting too long before sending the kit will result in invalid test results.

Step 3: Reseal the package to send to the lab

Send to the lab specified on the package for analysis. Due to time sensitivity, we recommend taking the test kit into the post office and putting it in a slot inside. You should receive your test results within a couple weeks.

Test results

The national average indoor radon level is estimated to be about 1.3 pCi/L, and about 0.4 pCi/L of radon is normally found in the outside air. The U.S. Congress has set a long-term goal that indoor radon levels be no more than outdoor levels. While this goal is not yet technologically achievable in all cases, most homes today can be reduced to 2 pCi/L or below.

Sometimes short-term tests are less definitive about whether or not your home is above 4 pCi/L. This can happen when your results are close to 4 pCi/L. For example, if the average of your two short-term test results is 4.1 pCi/L, there is about a 50% chance that your year-round average is somewhat below 4 pCi/L. However, EPA believes that any radon exposure carries some risk – no level of radon is safe. Even radon levels below 4 pCi/L pose some risk, and you can reduce your risk of lung cancer by lowering your radon level.

If your living patterns change and you begin occupying a lower level of your home (such as a basement) you should retest your home on that level.

Even if your test result is below 4 pCi/L, you may want to test again sometime in the future.

High radon levels? What’s next

Learn about your options for reducing the radon in your home.

What to do next

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There are many kinds of low-cost “do-it-yourself” radon test kits you can get through the mail and in hardware stores and other retail outlets.If you prefer, or if you are buying or selling a home, you can hire a qualified tester to do the testing for you. You can also contact a private radon proficiency program for lists of privately certified radon professionals serving your area.

Long-term testing

Long-term tests remain in your home for more than 90 days. “Alpha track” and “electric” detectors are commonly used for this type of testing. A long-term test will give you a reading that is more likely to tell you your home’s year-round average radon level than a short-term test.