Homeowner guide

How do I test my home for radon?

Last reviewed November 2026. The agency pages linked in this guide were checked November 5, 2026. Dates are Mountain Standard Time (Phoenix).

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Start with a short-term test. A kit is enough for many homes. Hire a qualified tester if you are buying or selling, or if you would rather not place the test yourself. EPA's Citizen's Guide says testing is easy, and that you cannot see radon (EPA: A Citizen's Guide to Radon (2016 edition)). CDC says radon is an odorless, invisible radioactive gas, and that the only way to know the level in a home is to test (CDC: Radon and Your Health).

If the first result is 4 pCi/L or higher, do a follow-up test before you decide to fix the home. Then read what a high radon result means.

What to do next

Kit or a pro

EPA's Citizen's Guide says low-cost do-it-yourself kits are available by mail and in some hardware stores and other stores. If you prefer, or if you are buying or selling a home, you can hire a qualified tester. Contact your state radon office first for a list of qualified testers. You can also contact a private radon proficiency program (EPA: A Citizen's Guide to Radon (2016 edition)). The guide points to EPA's finder (EPA: Find a test kit or professional).

That finder page says the National Radon Program Services at Kansas State University offers discounted kits, that many kits are sold online and in home-improvement stores, and that some state programs offer free or discounted kits. It also says to contact the state radon program if you want someone to test or fix the home (EPA: Find a test kit or professional).

EPA says states that receive indoor radon grants must keep a public list of providers credentialed either through the state's own process or through one of two national programs: the National Radon Proficiency Program (NRPP) or the National Radon Safety Board (NRSB) (EPA: Find a test kit or professional). A listing on remediationpros shows License on record from an official roster. Confirm the current status with the issuing agency before you hire.

CDC says you can contact your state radon office or buy a kit in a hardware store or online, and that you should send a kit to an approved laboratory (CDC: Radon and Your Health). EPA's radon FAQ page is the index for questions such as how to get a kit and how often to retest (EPA: Radon frequently asked questions). The steps below are the ones in the Citizen's Guide, which is the document that page points people toward.

How EPA says to place a short-term kit

Follow the instructions that come with the kit. These are the placement rules in EPA's Citizen's Guide (EPA: A Citizen's Guide to Radon (2016 edition)).

  • Short-term tests stay in the home for two days to 90 days, depending on the device. Long-term tests stay more than 90 days. A long-term test is more likely to reflect the year-round average, because levels change from day to day and season to season.
  • For a short-term test, close windows and outside doors and keep them closed as much as possible during the test. Fans that only recirculate indoor air may run. Do not run fans or machines that bring in outdoor air. A radon-system fan, and small exhaust fans used only for short periods, may run.
  • For a short-term test of just 2 or 3 days, close windows and outside doors at least 12 hours before you start. Do not run that short test during an unusually severe storm or unusually high winds.
  • Put the kit in the lowest lived-in level. That is the basement if people use it often; otherwise the first floor. Use a room people use regularly, such as a living room, playroom, den, or bedroom. Do not put it in the kitchen or bathroom.
  • Place it at least 20 inches above the floor, where it will not be disturbed, away from drafts, high heat, high humidity, and exterior walls. Leave it for as long as the package says. Reseal it and send it to the lab named on the package right away.

EPA's three testing steps

This is the decision order in the Citizen's Guide (EPA: A Citizen's Guide to Radon (2016 edition)).

  • Step 1. Take a short-term test. If the result is 4 pCi/L or higher, take a follow-up test.
  • Step 2. Follow up with a long-term test if you want a better read of the year-round average. Follow up with a second short-term test if you need results quickly. If the first short-term result is more than twice EPA's 4 pCi/L action level, take a second short-term test immediately.
  • Step 3. If you followed up with a long-term test, EPA says to fix the home if that result is 4 pCi/L or more. If you followed up with a second short-term test, consider fixing the home if the average of the two short-term results is 4 pCi/L or higher. Results close to 4 pCi/L are less certain. EPA says no level of radon is safe.
  • During a home sale, the Citizen's Guide says two short-term tests can be used to decide whether to fix the home, including two tests placed side by side about four inches apart. Buyers often want a test by someone who is not involved in the sale.

What a test costs

These are figures already published on the radon mitigation cost guide, not a new price survey. The National Radon Program Services page lists a short-term kit (2–4 days) at $20, including lab analysis, and a long-term kit (3–12 months) at $30, including lab analysis (National Radon Program Services, Kansas State University). Those kit durations are the ones on that page. They are narrower than the Citizen's Guide ranges of two days to 90 days for short-term devices and more than 90 days for long-term devices (EPA: A Citizen's Guide to Radon (2016 edition)).

Pennsylvania DEP describes a state-certified lab test kit at about $20–$30 (Pennsylvania DEP news release (Jan 9, 2025)). In the 2024 industry survey summarized on the cost guide, the most common bracket for a professional radon measurement in a single-family home was $151–$200 (47% of responses) (The Radon Reporter industry survey, as summarized by AdeptPlus). The cost guide also lists other survey brackets and consumer-reported kit prices. Those national figures are not a price for one home.

FAQ

Should I use a kit or hire someone?

EPA says a do-it-yourself kit is a normal way to test, and that you can hire a qualified tester if you prefer or if you are buying or selling (EPA: A Citizen's Guide to Radon (2016 edition)). Contact the state radon program for a list. EPA's finder names NRPP and NRSB as the two national proficiency programs on state grant lists (EPA: Find a test kit or professional).

Where does the kit go?

In the lowest lived-in level, in a room you use regularly, not the kitchen or bathroom, at least 20 inches above the floor. For a 2 or 3 day test, close windows and outside doors at least 12 hours beforehand and keep them closed as much as possible (EPA: A Citizen's Guide to Radon (2016 edition)).

What if the first result is 4 pCi/L or higher?

Take a follow-up test. Use a long-term test for a year-round average, or a second short-term test if you need a faster result. If the first result is more than twice the 4 pCi/L action level, EPA says to take a second short-term test immediately (EPA: A Citizen's Guide to Radon (2016 edition)). See what the level means.

How much does a radon test cost?

A National Radon Program Services short-term kit is $20, including lab analysis, and a long-term kit is $30, including lab analysis (National Radon Program Services, Kansas State University). Pennsylvania DEP lists about $20–$30 for a state-certified lab kit (Pennsylvania DEP news release (Jan 9, 2025)). The 2024 survey's most common professional-measurement bracket was $151–$200 (The Radon Reporter industry survey, as summarized by AdeptPlus).

How often should I test again?

EPA's Citizen's Guide says to test again after the home is fixed, and that it is a good idea to retest every two years. Also retest if you start using a lower level of the home, such as a basement (EPA: A Citizen's Guide to Radon (2016 edition)). The questions are indexed on EPA's radon FAQ page (EPA: Radon frequently asked questions).

Sources

Each link was checked November 5, 2026. Dollar figures in this guide are copied from the radon cost guide and its sources. They are not new ranges.

Contractors by state

These links go only to states where the directory currently lists radon mitigation contractors.

This guide is general information from public sources such as EPA, CDC and HUD. It is not medical, legal or professional advice. Rules differ by state and city; check with your state health or environmental agency before starting work. If you have health concerns, talk to a doctor. Contractors listed on remediationpros show 'License on record' from official rosters; confirm current status with the issuing agency before hiring.