Learn About Radon Testing

Radon testing is a measurement done to detect the presence of radon gas in our homes. As the second leading cause of lung cancer and a potential role in non-Hodgkin's lymphoma, radon is an odorless, colorless gas that can only be detected by testing, and the Environmental Protection Agency recommends that everyone test their home. Both short-term and long-term tests are available, with short-term tests found in many hardware stores. If levels are abnormal, radon mitigation can almost always solve the problem and eliminate your risk.

Magnitude of the Problem

Many people associate lung cancer with smoking alone, yet the majority (well over 50 percent) of people diagnosed with lung cancer today are non-smokers; they either never smoked or quit smoking long ago. In order to understand the magnitude of radon-induced lung cancer, it's thought that it is responsible for roughly 21,000 to 27,000 deaths from lung cancer each year in the United States. In comparison, around 40,000 women die from breast cancer each year. If we had a way to prevent one-half to three-fourths of breast cancer deaths completely with a very inexpensive test and mitigation if necessary, it's likely that most people would have heard the news. Yet, we do have a way to prevent this many lung cancer deaths.

Why Testing for Radon Is Important

Radon gas is an invisible, odorless gas that is produced by the normal breakdown of uranium in the soil. Although some regions of the U.S. have higher levels of radon, elevated levels have been found in homes in all 50 states, and around the world. At the present time, it's estimated that 1 out of 15 homes in the United States have elevated radon levels. Thankfully, if elevated radon levels are detected and repaired, this cause of lung cancer is entirely preventable. Radon testing is easy, inexpensive, and doesn’t even require willpower.

Who Should Test for Radon?

Since radon is an odorless, colorless gas, the only way to know if levels are abnormal in your home is through testing. The EPA recommends that every home in the United States be tested for radon. In the past, some people thought that homes without basements were not at risk, but this is not the case. Any living area below the 3rd floor of a building should be tested.

Radon Levels: Normal and Abnormal

Radon is present in small amounts in the air throughout the world. The average level of radon in outdoor air is 0.4 pCi/L (pico Curies per Liter), and the average level in indoor air is 1.3 pCi/L.

The Environmental Protection Agency (EPA) recommends fixing your home if the radon level is above 4 pCi/L. They also state that individuals should consider repairs if the level falls between 2 pCi/L and 4 pCi/L

It can be difficult to compare risks with all of the media alerts you hear, but if you wouldn't allow smokers in your home, you should definitely consider fixing levels above 2 pCi/L.

Relative Risk of Radon Exposure

Exposure to radon in our homes is the second leading cause of lung cancer overall and the number one cause in non-smokers. To put the risk of radon in perspective, the EPA has a chart in which they compare the risk of radon to other risks. At a level of 4 pCi/L, the risk that non-smokers will develop lung cancer due to radon is about the same as the risk of dying in a car crash. For smokers, exposure to radon is of even greater concern. At a radon level of 4 pCi/L, the risk of developing lung cancer is 5 times the risk of dying in a car crash.

Radon and Non-Hodgkin Lymphoma

A 2016 study suggests that indoor air radon exposure may also increase the risk of blood-related cancers (such as leukemia, lymphomas, and multiple myeloma) in women, and the effect of radon levels may even be more significant. A different 2017 study conducted in Korea estimated that every 10 Bq/m3 increase in indoor radon was associated with a one percent increase in the risk of lung cancer in males but a seven percent increase in the risk of lymphomas in female children and adolescents. While it's not known whether this is simply a geographical correlation or instead implies causation, we do know that radon emits alpha particles that can damage DNA in the bone marrow, with DNA damage (mutations) being the underlying cause of cancer.

Radon Testing Methods

Both short-term and long-term tests are available to test for radon. Short-term tests are good if you want an instant reading of the status of your home. They are also important as part of an inspection before buying a home.

Short-Term Tests

Short-term tests are the fastest way to detect elevated radon levels in your home and are performed over a period of 2 to 90 days (most test kits are done over 2 to 4 days). Do-it-yourself short-term kits are available at most hardware stores, and can also be ordered online or by phone (see below). Many home inspection agencies offer radon detection as part of a home inspection. Based on the number of homes that have elevated levels around the world, and cost (both financially and physically) to your health, these tests are a very small investment.

Long-Term Tests

Long-term tests are conducted over a period more than 90 days. Radon levels fluctuate throughout the year and are highest during cold weather when heating is used and windows are closed. These tests can give an indication of what the average level of radon is in your home year-round. Most often, long-term tests are used by those who have done radon mitigation and want to make sure whatever radon mitigation measures they have taken are working.


Both passive and active devices can be used for radon testing. Passive devices, such as charcoal canisters, do not require power and are widely available. Active devices require power to run and can provide continuous monitoring of radon levels. These devices are usually used by a certified radon testing company rather than as a do-it-yourself test and are usually more expensive.


Most hardware stores carry short-term radon test kits that cost less than $20. Free or discounted kits are often available (especially during Radon Awareness Month in January) through state or county health departments. If you are interested in a qualified tester for radon, check with your state radon contract information. By phone, discounted test kits can be purchased at 1-800-SOS-RADON.​

How to Test for Radon

Carefully read and follow the manufacturer’s directions on your radon test kit. Some of these are very specific. For example, if your test is left out for more than the required amount of time, improperly sealed, or there is a delay between the test time and when you mail the test, your sample may be rejected. Most test kits recommend the following:

  • Place the test kit in the lowest area of living space in your home.
  • Keep windows and doors closed (except for entering and leaving) for 12 hours prior to testing your home, and throughout the duration of the test (short-term tests).
  • Avoid placing the test kit in the kitchen, bathrooms, hallways, laundry room, and rooms that may be drafty.
  • Place the kit at least 20 inches off the floor.

Special Situations

In addition to entering your home through the soil, radon may be present in well water, or in items that we introduce into our homes such as granite countertops. If you are concerned about the possibility of radon in your water, check with your state radon contact. General information about radon in drinking water is available through the EPA’s Safe Drinking Water Hotline at 1-800-426-4791.

What to Do If Your Radon Levels Are Above Normal

If your radon level is above 4 pCi/L, the first step it to repeat the test. If the average of the tests remains above 4 pCi/L, it is recommended that you contact a professional to perform radon mitigation (see resources below). We can't emphasize enough the importance of contacting a professional who is well versed in radon mitigation. In the long run, this can make a big difference in your health, as well as your wallet.

Radon Mitigation—Finding a Certified Professional

If your radon levels are elevated, it important to have your home repaired to reduce your families risk of lung cancer. Your state radon contact can provide you with a list of certified radon mitigation experts in your area. Take a moment to learn more about radon mitigation in case you will need to look into options, or have friends, neighbors, or family who will be facing a similar concern in the future.

A Word From Verywell

Testing for radon is one of the least expensive ways to reduce your risk of developing cancer. We hear a lot about of mammograms which may play a role in detecting cancer early in some women, but with radon testing, we have a way to test, and prevent, the most common type of cancer from developing completely.

Of more concern is that radon exposure, since it occurs in the home, leaves children at the greatest risk. We do everything possible to keep our children healthy, but we're not often thinking about how to improve their quality of life and life expectancy when they are 40 or 50. But whether you have children or not, test your home for radon today. No home is safe until you see an objective number, and even experts are shocked every day to learn about homes that are risky. You, your health, and your family are worth it.

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