What is radon?

Radon is a cancer-causing radioactive gas. It comes from the breakdown of uranium, which is a natural part of soil and rock. Radon is found in rock, soil, water, building materials (such as granite or shale), and natural gas. Radon cannot be detected by human senses because it is odorless, tasteless, and invisible.

How does radon exposure occur?

Any home, school, office, or other building can have a radon problem. Radon may seep in through cracks and pores in the foundation of a house built on radon-contaminated soil. Radon is found in many homes, new and old, well-sealed or drafty. You don't have to have a basement to have a radon problem. The radon can then become trapped inside, especially if the home is well-insulated.

Radon is found in homes all over the world and has been found in every state in the United States. Studies have shown that nearly 1 out of every 15 homes in the U.S. has unsafe levels of radon.^{1, 2} The U.S. Surgeon General and the U.S. Environmental Protection Agency (EPA) recommended in 2005 that all homes be tested for radon levels.

What are the health effects of radon exposure?

Long-term exposure to radon has been linked with lung cancer. Radon is now the second leading cause of lung cancer, after tobacco smoking. It is estimated to cause about 21,000 lung cancer deaths per year in the U.S.¹ The risk of lung cancer is even higher when these causes are combined: smokers have a significantly higher risk for radon-associated lung cancer than nonsmokers.

Can radon exposure be prevented?

You can greatly reduce levels of radon in home, school, and work environments either by preventing it from entering buildings or by venting it out. When having radon professionally vented from your home or office, it is important to have a reputable company's help in following the guidelines set up by the EPA. If you live outside the United States, you can contact your regional environmental protection office for more information.

Frequently Asked Questions

Health Effects of Radon Exposure

When radon starts to decay, very tiny radioactive particles are released. If you inhale these particles, they enter the lungs and may cause cancerous changes in nearby cells. If you breathe in radon, you have a greater chance of getting lung cancer.³

Radon is the second leading cause of lung cancer, second only to tobacco smoke. It is responsible for about 21,000 deaths from lung cancer per year in the United States.¹

The U.S. Surgeon General and the U.S. Environmental Protection Agency (EPA) recommend that all homes be tested for radon levels.

The combination of smoking and radon exposure can greatly increase your risk of developing lung cancer. If you smoke or live with someone who smokes and you live or work in a place with dangerous radon levels, your risk of lung cancer is significantly higher than for someone who has never smoked but lives or works in places with unsafe radon levels. It is never too late to reduce your risk of lung cancer. Don't wait to test for and fix a radon problem. And if you smoke, try to quit. For more information, see the topic Quitting Smoking.

Radon exposure does not produce immediate symptoms. You may not realize that you are being exposed to dangerous levels of radon until you or someone in your family is diagnosed with lung cancer.

What Increases Your Risk of Radon Exposure

When uranium decays, it releases radon. Since uranium occurs naturally in soil and rocks, radon is found all over the world. Nearly 1 out of every 15 homes in the U.S. has elevated radon levels.¹ Also, if you live or work in an area that has large deposits of uranium (to see a map of the U.S. radon zones, go to the Web site www.epa.gov/radon/zonemap.html), you may be more likely to be exposed to high levels of radon. But factors relating to the specific construction and location of your house may be just as likely to affect your risk of radon exposure as the source of the radon itself. Even houses right next to each other can have very different radon levels.

Radon enters a home or building through cracks in the foundation or walls, through basement floors, and in water supplies (such as private wells). If the water supply contains radon, it may enter the air in the home through faucets, showers, dishwashers, or washing machines. Radon may also enter the home through pipes, sumps, or drains.

Radon is also found in many building materials. But building materials rarely cause a radon problem all by themselves.

Radon is heavier than air, so it is often found in higher concentrations in lower levels of buildings, such as in basements and sumps. Since radon is odorless, tasteless, and invisible, it is wise to test your home and office for radon levels no matter where you live or work.

How to Test for Radon

Testing for radon can be done with a do-it-yourself home test. Use only home tests that are labeled "meets EPA requirements." The two types of home tests used to detect radon are short-term and long-term.

You can purchase an EPA-qualified short-term or long-term detector test kit at hardware or retail stores or through government agencies in the United States, including:

• Your regional U.S. Environmental Protection Agency. Find your regional office by going to the EPA Web site (www.epa.gov/iaq/whereyoulive.html) or by calling the EPA National Radon Hotline at 1-800-SOS-RADON (1-800-767-7236).
• The Consumer Federation of America Foundation's Radon FIX-IT Program hotline at 1-800-644-6999.

If you don't want to do the test yourself or if you are buying or selling a home, you can hire a qualified tester to do the testing for you. Contact your state radon office for a list of qualified testers.

• The short-term test kit stays in your home or office for 2 to 90 days. Radon levels vary daily and from season to season. So you may want to follow up the first short-term test with a second to determine whether reduction in radon is needed.
• The long-term test kit stays in the home or office for more than 90 days. A long-term test will give more accurate results because radon levels can fluctuate from season to season.

These tests work by measuring average indoor levels of radon in your home or office. Radon is measured in units of radioactivity per volume of air. The most common measure is picocuries per liter of air (pCi/L). The average indoor level of radon is estimated to be about 1.3 pCi/L, while the average outdoor level of radon is about 0.4 pCi/L.¹ Levels that equal or exceed 4 pCi/L should be reduced. But the EPA says there is no safe level of radon. Radon levels between 2 pCi/L and 4 pCi/L can be reduced as well. Removing radon sources or venting radon should be done by a contractor specifically trained and certified to fix radon problems.

How to Prevent, Reduce, or Remove Radon

If your home or workplace has a high level of radon, you should take measures to reduce it. The goals of radon reduction are to:

• Prevent radon from entering the building.
• Vent or remove radon once it has entered the building.

The most common and usually most effective way to prevent radon from entering the home is through sub-slab depressurization, which involves venting air from beneath the foundation. Another way to remove radon-containing air from a building involves placing heavy plastic over the soil in earth-floored crawl spaces and using a fan and pipes or duct work to vent the radon to the outside (from under the plastic). This technique needs to be performed by qualified contractors who have completed training in a national radon proficiency program. You can locate a qualified contractor by contacting your local EPA office (find your regional office by going to the EPA Web site www.epa.gov/iaq/whereyoulive.html) or by calling the EPA National Radon Hotline at 1-800-SOS-RADON (1-800-767-7236).

The first step in reducing the level of radon in your home or office involves simple venting methods. Contact an EPA-qualified contractor to advise you or help you with ventilation of contaminated areas.

Methods of ventilation can include:⁴

• Opening windows.
• Installing vents in basements or crawl spaces.
• Increasing air movement with ceiling fans.
• Venting air outside the house from sump holes or floor drains.

The balance of air exchange is important to properly remove radon from the home or office. This is why it is essential to have a contractor properly trained in radon reduction to help with ventilation procedures.

Other control methods used to reduce radon include sealing cracks in the foundation or walls and using air cleaners.⁴

Once radon reduction or prevention procedures are done, the home or building should be retested. You may need to retest the home or building more than once until the radon level falls below the acceptable level of less than 4 pCi/L. It is usually safe to continue living in the home or building while the radon is being vented, but you may want to confirm this with your local EPA office.

Helpful Resources

In the United States, you may locate a contractor qualified to remove radon by contacting your local Environmental Protection Agency office (find your regional office by going to the EPA Web site www.epa.gov/iaq/whereyoulive.html) or by calling the EPA National Radon Hotline at 1-800-SOS-RADON (1-800-767-7236). The contractor should be able to show you a certification from a national radon proficiency program demonstrating that he or she has gone through special training to remove or reduce radon levels in your home or office.

Most countries have agencies that provide information about environmental protection. Contact your local environmental agency for more information about radon exposure in your area.

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