Radon guide
How to test your home for radon
Radon has no smell or color, so a test is the only way to know your level. Setting one up takes a few minutes; the waiting is done by the kit.
Pick a test
If you need an answer soon, run a short-term test and follow it with a second one; EPA accepts the pair as a basis for deciding whether to fix. If you can wait, a long-term test tells you more. Low-cost kits are sold by mail and in some hardware stores, and your state radon office keeps a list of qualified testers.
Set it up
- Choose the floor. Use the lowest level of the home that people use regularly: the basement if someone spends time there, otherwise the first floor.
- Choose the room. Pick a room people use, such as a living room, den, playroom or bedroom. EPA asks you to leave out the kitchen and bathroom.
- Place the kit. Set it at least 20 inches above the floor, where nobody will move it, away from drafts, heaters, damp spots and outside walls.
- Close up the house. For a test shorter than four days, shut windows and outside doors at least 12 hours before you start and keep them closed apart from normal coming and going.
- Write down the start. Note the date and time on the form that came with the kit.
While the test runs
| Fine to use | Avoid |
|---|---|
| Heating and central air that recirculate indoor air | Window fans or anything that pulls in outdoor air |
| Bathroom or kitchen exhaust fans for short periods | Open windows, except normal entry and exit through doors |
| A radon reduction fan, if the home already has one | Short tests during severe storms or very high winds |
When the time is up
Record the stop date and time, reseal the kit as the instructions say and mail it to the lab right away, as the kit's instructions require. Labs usually report within a few days to a few weeks. If you are on a deadline, ask about faster service before you mail it.
Reading the result
EPA recommends fixing a home at 4 pCi/L or higher and suggests considering it between 2 and 4. A single short-term result above 4 should be confirmed: either with a second short-term test, averaging the two, or with a long-term test if you can wait. Our radon level checker explains any number you enter.
Hiring a tester instead
If you are buying or selling a home, or simply prefer not to do it yourself, a certified tester can place the device and handle the paperwork. Ask your state radon office for a list, or check that the person holds a state license or a national proficiency certification. See radon during a home sale for the testing options EPA describes for real estate deals.
Sources: EPA, A Citizen's Guide to Radon (2016); EPA, Home Buyer's and Seller's Guide to Radon (2024). Updated October 2026.