How to Test Your Home for Radon (USA)

Two Parts:Testing Your Home for RadonInterpreting Results

Radon is an odorless gas that decays into radioactive particles that can get trapped in your lungs when you breathe, which damages tissues and increases your risk of lung cancer. In fact, radon is the second leading cause of lung cancer in the USA and claims as many as 21,000 lives per year.[1] Radon comes from the breakdown of uranium in soil, rock and water and can enter your home through porous building materials or leaks in your foundation. Learn how to test your home for radon and reduce the health risks to your family.

Part 1
Testing Your Home for Radon

  1. Image titled Test Your Home for Radon (USA) Step 1
    Buy or order a testing kit. There are numerous kinds of low-cost “do-it-yourself” radon test kits that you can either buy from a local hardware or home improvement store, or order online.[2] Depending on where you live, you might qualify for a free testing kit. Be aware that there are two categories of radon air tests: short-term and long-term.
    • Short-term radon tests are the most common and convenient. They measure radon levels for between 2-7 days, depending on the device. Homeowners should use use short-term testing.
    • Long-term tests measure radon levels for 90 days to one year. These radon tests give results more reflective of seasonal or year-round average radon levels in your home.[3] Long-term testing should be done by professionals.
    • Whatever radon test kit you get, make sure it meets the Environmental Protection Agency's (EPA) requirements.
  2. Image titled Test Your Home for Radon (USA) Step 2
    Close your doors and windows. Before you can get an accurate sample of the air in your home, you'll need to close all of your exterior doors and all of your windows. Close them at least 12 hours prior to and throughout the testing period, which can be up to 7 days with some short-term radon tests.[4]
    • Heating and A/C systems, as well as fans that re-circulate air in your home may be operated while radon testing.[5]
    • However, don't operate fans or other machines that bring in air from the outside — it can contaminate your results.
    • You shouldn't conduct short-term radon testing during unusually severe storms or when it's really windy outside. Wait for calm weather.
  3. Image titled Test Your Home for Radon (USA) Step 3
    Find a place to position your radon kit. Your radon test kit should be placed in the lowest level of your home that you spend a significant amount of time in.[6] This could mean the basement level if you frequently use it, or the first floor if you don't use or have an underground basement.
    • Choose a room that you use regularly, such as the living room, playroom, office or bedroom.
    • Don't set the testing kit up in your kitchen or bathrooms, because humidity and various fumes can affect or contaminate the results.
    • Whatever room you choose, position the testing kit at least 20 inches above the floor — use a small sturdy table if need be. Make sure it's away from drafts, high heat, humidity and exterior walls.[7]
  4. Image titled Test Your Home for Radon (USA) Step 4
    Leave the radon-sensitive material in place. After reading the instructions, take out the material that's radon sensitive and leave it on a sturdy table (at least 20 inches from the floor) for the specified time frame — typically between 2-7 days for most short-term kits. Short-term test kits use either special charcoal canisters, liquid scintillation vials or continuous radon monitors that are electronic.[8]
    • Whichever type of material your kit contains, take it out of the package, remove the top(s) to expose it to the air and place it on the table.
    • If your kit has the liquid scintillation vials, place the two vials about 6 inches apart on the table for best results.
  5. Image titled Test Your Home for Radon (USA) Step 5
    Collect the test material and mail it away. After the specified time frame is up, put the tops back on either the charcoal canisters or liquid scintillation vials, place them back into their original packaging and reseal it tightly.[9] Once safely resealed, send it via registered mail to the lab specified on the package for analysis.
    • Make sure to send in your package to the lab shortly after the testing period has ended for the most accurate results. Don't wait much more than a day or two.
    • You should receive your radon test results from the lab within a few weeks, both by regular mail and via email. With most labs, you can check your results online.
    • The results may look complicated, but remember that radon in the air is measured in pico Curies per liter of air or pCi/L (see below).
  6. Image titled Test Your Home for Radon (USA) Step 6
    Use an electronic radon monitor instead. As noted above, using an electronic radon monitor in your house is an alternative, although they're typically used by testing professionals — and the price reflects this. Electronic radon monitors are placed face-up on a stable table or any flat surface where the ventilation slots on the device are not blocked.[10] Electronic detectors provide a continuous reading of radon levels in your home, which can be easily seen from a digital display.
    • An advantage of using an electronic radon monitor is you'll be able to read the results immediately after the testing period has expired. No need to send it away to a lab for analysis.
    • The main disadvantage is the price. Some units cost upwards of $1,000, although they're marketed for professional use.
    • In most cases, electronic radon detectors are used in conjunction with charcoal and vial methods — it's not meant to replace the more traditional methods.
  7. Image titled Test Your Home for Radon (USA) Step 7
    Hire a professional to test your home. As an alternative to doing it yourself, you can hire a qualified radon tester to do the testing for you. Contact your state radon office or email an online training program about getting a list of qualified testers. It will be more expensive than doing it yourself, but you'll have the peace of mind that it's being done correctly and the results interpreted properly.
    • Long-term radon testing should always be done or monitored by a qualified radon measurement professional.
    • An advantage of getting your home professionally monitored for radon gas is that the testing team can recommend (or in some cases provide) an experienced crew to fix the problem.
    • Some radon reduction systems can reduce levels in your home by 99% — even very high levels can be reduced to much safer levels.[11]

Part 2
Interpreting Results

  1. Image titled Test Your Home for Radon (USA) Step 8
    Understand the results. The amount of radon in the air is measured in pico Curies per liter of air or pCi/L. The average indoor radon level is estimated to be about 1.3 pCi/L, whereas about 0.4 pCi/L of radon is typically found in the outside air.[12] According to most health authorities, 4 pCi/L of radon is the cutoff point between acceptable and unsafe.
    • Short-term testing can be less definitive about whether your home is above 4 pCi/L or not if it's close to that amount — there is a margin of testing error.
    • Thus, any reading over 3.5 pCi/L should be considered fairly high and reason to do more testing.
    • It's important to remember that radon isn't safe at any level, so readings below 4 pCi/L still pose some risk of lung cancer and other lung diseases.
  2. Image titled Test Your Home for Radon (USA) Step 9
    Do another short-term test if levels are high. If the results from your initial test are close to or over 4 pCi/L, then that's an indication to take action.[13] The first step you should take it is to do another short-term test in your home, preferably one that's made by another manufacturer. Alternatively, use a different testing medium — switch from liquid scintillation vials to charcoal canisters, for example.
    • There is some degree of error with radon testing, so change the variables and see if you get similar results.
    • If the average of your 2 short-term test results is around 4.1 pCi/L, then there is about a 50% chance that the year-round average in your home is actually below 4 pCi/L.[14]
  3. Image titled Test Your Home for Radon (USA) Step 10
    Get a long-term test done if levels are still high. If radon levels in your home still appear to be high (4 pCi/L or above), then you should get a long-term test done.[15] Long-term radon testing can be done by homeowners, but getting a qualified professional involved is likely a much better idea due to what's at stake (your health and/or the cost of fixing the problem).
    • Remember that radon levels in your home can change from month to month, and season to season, so a long-term test is the most definitive way of knowing your health risks.
    • If the long-term radon test shows that levels are 4 pCi/L or higher, then you should make a plan to fix your home.
    • Fixing a radon problem is sometimes recommended if it's found to be over 2 pCi/L.
    • Although it's not an inexpensive fix, most modern homes can be reduced to a radon level of 2 pCi/L or below.[16]


  • Some states and counties offer free radon test kits. Check to see if you're able to take advantage of these programs first before buying a kit.
  • Radon can penetrate all types of foundations, including crawlspaces and slab-on-ground basements.
  • Elevated levels of radon can be found in both new and old buildings, whether they are homes, workplaces or stores etc.
  • One of the things that the EPA recommends is the installation of a special vent pipe system and fan, which pulls radon from beneath your house and vents it to the outside — this system is called suction radon reduction.
  • Sealing foundation cracks and other openings makes any kind of venting system more effective and cost-efficient.
  • If the air in your home has tested high for radon, then get your water tested, especially if you use well water.

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