Radon and Cancer Risk

If you are concerned about radon from household sources, you can test for radon. Learn more in “Testing your home for radon” below.

Radon exposure at certain jobs

In the workplace, people working underground, such as some types of miners, are among the most likely to be exposed to high levels of radon.

Higher levels of radon exposure are also more likely for people who work in uranium processing factories or encounter phosphate fertilizers that may have high levels of radium (an element that can break down into radon).

Can radon cause cancer?

Yes. Being exposed to radon for a long period of time can lead to lung cancer. Radon and its progeny are absorbed in the body mainly by inhaling into the lungs, and the radiation they give off travels only a short distance, so other tissues in the body get much smaller amounts of radiation.

Radon and lung cancer

Radon gas in the air breaks down into tiny radioactive elements that can be breathed in and lodge in the lining of the lungs, where they can give off radiation. This radiation can damage lung cells and, over time, lead to lung cancer.

Cigarette smoking is by far the most common cause of lung cancer in the United States, but radon is the second leading cause. Experts estimate that about 21,000 lung cancer deaths each year in the US are related to radon.

Exposure to both radon gas and cigarette smoke creates a greater risk for lung cancer than either factor alone. Most radon-related lung cancers develop in people who smoke. However, radon is also thought to cause a large number of lung cancer deaths each year among people who don't smoke.

The evidence that radon causes lung cancer comes from both studies in people and studies done in the lab:

Studies have found that exposure to radon leads to higher lung cancer risk in people working in underground mines, in people living in homes with higher levels of radon, and in people who live in areas where radon levels are higher.

Studies in lab animals have found an increased risk of lung tumors with exposure to radon.

• In lab studies using human cells, radon and its progeny have also been shown to cause damage to chromosomes (packets of DNA) and other types of cellular damage often seen in cancer cells.

What expert agencies say

Several agencies study different substances in the environment to determine if they are carcinogenic (cancer causing). The American Cancer Society looks to these groups to evaluate the risks based on the available evidence.

• The International Agency for Research on Cancer (IARC) is part of the World Health Organization (WHO). One of its goals is to identify causes of cancer. IARC classifies radon and its progeny as “carcinogenic to humans,” based on sufficient evidence that they can cause lung cancer.
• The National Toxicology Program (NTP) is an interagency program of US government agencies, including the National Institutes of Health (NIH), the Centers for Disease Control and Prevention (CDC), and the Food and Drug Administration (FDA). The NTP has classified radon as “known to be a human carcinogen.”
• The US Environmental Protection Agency (EPA) monitors the human health effects from exposure to various substances in the environment. The EPA lists radon as the second leading cause of lung cancer and the number one cause of lung cancer among people who don't smoke.

For more information, see Known and Probable Human Carcinogens.

Radon and other cancers

Some studies have suggested that radon exposure might also be linked to some other types of cancer, such as adult and childhood leukemia. But the evidence so far has been mixed and not nearly as strong as it is for lung cancer. More research is needed to explore these possible links.

How to reduce your risk of radon exposure at home 

Radon is in the air we breathe, both indoors and out. It isn’t possible to avoid it completely, but there may be things you can do to lower your exposure.

Testing your home for radon

For most people, the largest potential source of radon exposure is in your home. Because radon gas can’t be seen or smelled, the only way to know whether you're being exposed is to test for it.

You can hire a professional or do it yourself with a kit you buy at a hardware store or online. Follow the instructions for leaving the kit in your house for the required number of days. Then mail it to a lab and wait for the results.

Short-term kits are usually left in place for 2 to 90 days. Long-term kits, which give a more accurate assessment of your home’s year-round average radon level, are usually left in place for 3 months or longer. The EPA recommends testing all homes below the 3^rd floor, even new homes that were built “radon-resistant.”

It is also possible for radon to enter your home through your water supply, though this poses a much lower risk than when it comes through the soil. If you have a private well, you can have it tested for radon. If you have public water supply, contact your supplier if you have questions about radon levels.

What to do if radon levels are high (radon mitigation)

The EPA recommends taking steps to lower radon levels if test results show levels of 4 pCi/L or higher. They also suggest people consider addressing levels between 2 pCi/L and 4 pCi/L.

If radon levels in your home or water supply are high, you can take steps to lower them. Methods to mitigate radon may include:

• Having a vent pipe system and fan installed, which pulls radon from beneath the house and vents it to the outside
• Sealing cracks in floors and walls or increasing ventilation through “sub-slab depressurization” using pipes and fans
• Using building materials that may be more “radon tight” to help reduce exposure in areas where radon levels are high
• Having your water supply treated so radon is removed before entering your home

As with most home repairs, the cost of reducing radon in your home can vary based on how your home is built (whether you have a basement, crawlspace, or neither) and what kind of repairs you need.

It’s important to have a qualified contractor fix your home because lowering high radon levels requires specific skills. Without these, you could increase your radon level or create other problems and more costs. If you decide to do the work yourself, be sure you have the proper training and equipment.

Visit the EPA website to learn more about testing and how to reduce radon levels in your environment.

Protection from radon in the workplace

Federal agencies, such as the Nuclear Regulatory Commission (NRC) and the Occupational Safety and Health Administration (OSHA), set limits on exposure to radon (and radon progeny) in the workplace. Because radon is known to be a health hazard, underground mines now have features to lower levels.

For people who may be exposed to radon in the workplace, it’s important to follow recommended safety procedures. If you are concerned that your exposure might be above the allowed limits, contact your workplace safety officer or these agencies.

What should I do if I’ve been exposed to radon?

There are no widely available medical tests to measure exposure to radon.

If you smoke and have been exposed to higher levels of radon, it’s important to try to quit smoking. The combined effects of smoking and radon raise the risk of lung cancer much more than either exposure alone.

If you think you might have been exposed to high levels of radon over long periods of time, talk with your doctor about whether you should get regular checkups or screening tests to look for possible signs of lung cancer. Be aware of possible symptoms of lung cancer, such as shortness of breath, a new or worsening cough, pain or tightness in the chest, hoarseness, or trouble swallowing. Tell your doctor if you start to have any of these symptoms.

For uranium miners, millers, and transporters who have certain health problems because of exposure to radon, the United States government has established the Radiation Exposure Compensation Program. The program offers a lump-sum payment to people with lung cancer and certain other lung diseases if certain criteria are met. Information about the program is available online or by calling 1-800-729-7327 (1-800-729-RECP).