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Test6 min read

What is a radon test kit?

By Radon411 Editorial TeamUpdated How we research

Short answer

A radon test kit is a small, low-cost detector you set out in the lowest lived-in level of your home for a set time, then reseal and mail to a lab, which reports the radon level. Short-term kits stay out two days to 90 days, and long-term kits more than 90 days.

Next step: pick the right test for your home. Which test to use

To see the kits we cover side by side, go to radon test kits compared.

Most kits are passive detectors, such as charcoal canisters, alpha track detectors, electret ion chambers and charcoal liquid scintillation devices. They need no power, are generally inexpensive, and are sold online, by mail and in hardware and other retail stores. Free kits are sometimes available from local or county health departments or from state radon programs.

How you use the kit matters as much as which one you buy. Place it in the lowest lived-in level, at least 20 inches above the floor, away from drafts, high heat, high humidity and exterior walls. For a , keep windows and outside doors closed as much as possible, and leave the kit in place for as long as the package says; every radon test should run for a minimum of 48 hours.

A kit is different from a continuous monitor, an active device that needs power and continuously measures and records radon. When you are buying or selling a home, hiring a qualified tester is recommended.

What to do next: compare kits, check whether your state offers free or discounted kits, and read your result with the interpreter when it arrives.

At a glance · 1 min read

What a radon test kit is

A radon test kit is a small measuring device you set out in your home, leave for the time the package says, then reseal and send to the lab named on the package. Since you cannot see or smell radon, special equipment is needed to detect it, and a kit is the low-cost, do-it-yourself way to get that equipment into your home.

The detectors sold as radon test kits
DetectorShort-term testLong-term test
Charcoal canisterYesNo
Charcoal liquid scintillationYesNo
Alpha trackYesYes
Electret ion chamberYesYes
Show all 4 rows
Read moreA paragraph, 1 min

All four are passive devices: they need no power, they sit exposed to the air in the home for a set period, and then they go to a laboratory for analysis. Both short-term and long-term passive devices are generally inexpensive.

In a picture · 1 min read

Short-term and long-term kits

Kits come in two lengths. A short-term kit stays in the home for two days to 90 days, depending on the device, and gives a quick answer. A long-term kit stays for more than 90 days and tells you more about your home's year-round average, because radon levels vary from day to day and season to season.

TestHow long it runsWhat it is for
Short-term testStays in the home from 2 to 90 days, depending on the device, and for a minimum of 48 hours.A faster screening result. Because radon levels vary from day to day and season to season, it is less likely than a long-term test to tell you the year-round average.
Long-term testStays in the home for more than 90 days.It is more likely than a short-term test to tell you the home's year-round average radon level.
Short-term and long-term radon tests: how long each stays in the home and what it tells you.
Read moreA paragraph, 1 min

The longer the test, the better the result reflects your home's radon level and the way you live in it. Whichever you choose, every radon test should run for a minimum of 48 hours, and some devices need a longer minimum. If a first short-term result is high, take a followup test to be sure. See how long a radon test takes.

Step by step · 1 min read

How to use a radon test kit

  1. Step 1 of 5:

    Read the instructions

    Follow the instructions that come with your kit. The package says how long to leave the device out and where to send it.

  2. Step 2 of 5:

    Close up the house

    For a short-term test, close windows and outside doors and keep them closed as much as possible during the test.

  3. Step 3 of 5:

    Place the device

    Put it in the lowest lived-in level: the basement if it is frequently used, otherwise the first floor. In a multi-unit building, use the lowest level within your unit.

  4. Step 4 of 5:

    Record and leave it

    Record the start date and time, and do not disturb the device at any time during the test.

  5. Step 5 of 5:

    Send it off

    When the test ends, reseal the package and send it right away to the lab named on it. Results should arrive within a few weeks.

Read moreA note, 1 min

At a glance · 1 min read

Where to get a radon test kit

Kits are easy to find. Low-cost kits are sold through the mail, online and in hardware and other retail stores, and some places give them away.

Where radon test kits come from
WhereWhat to know
State radon programs and local or county health departmentsFree kits are sometimes available, and your state may offer free or discounted kits
National Radon Program Services at Kansas State UniversityKits are available to purchase online
Hardware, drug, home improvement and other storesPassive kits are sold in many retail and hardware stores
By mail from a measurement provider or laboratoryYou can order a kit by mail from a qualified radon measurement services provider or laboratory
Some local or state American Lung AssociationsSome offer test kits
Show all 5 rows
Read moreA paragraph, 1 min

For the free and discounted routes, see free radon test kits. To compare the kits themselves, see radon test kits.

At a glance · 1 min read

A kit, a monitor or a professional tester

A kit is not the only way to test. Active devices, continuous radon monitors and continuous working level monitors, need power and continuously measure and record radon or its decay products in the air. Many report how the level swung during the test, and a qualified tester can explain that report to you. These tests may cost more, but they may give a more reliable result.

Three ways to test a home for radon
OptionNeeds powerWhat you get
Passive test kitNoOne result for the test period, from a lab
Continuous monitorYesA record of the level through the test, which can reveal unusual swings
Qualified radon testerEither kindA tester, very often a home inspector, who uses a device suited to your situation

Questions · 1 min read

Questions about radon test kits

What does a radon test kit do?

It collects a sample of your home's air over a set period. You then send it to a lab, which reports the radon level.

How long does a radon test kit take?

A short-term kit stays out for two days to 90 days, depending on the device, and a long-term kit for more than 90 days. Every radon test should run for a minimum of 48 hours.

Can I get a free radon test kit?

Sometimes. Free kits are sometimes available from local or county health departments or from state radon programs, and your state may offer free or discounted kits.

Do I have to mail the kit to a lab?

For a passive kit, yes: reseal the package and send it to the lab named on it right away. A continuous monitor measures and records the level itself.

How soon will I get my results?

You should receive your results within a few weeks of sending the kit.

Where do I put a radon test kit?

In the lowest lived-in level, in a room used regularly but not the kitchen or bathroom, at least 20 inches above the floor.

What if my kit shows a high level?

Take a followup test to be sure, then read the results with the result interpreter.

Test

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