The short answer
Radon is an invisible, odorless gas that seeps into homes from the ground. It is the second leading cause of lung cancer after smoking. You cannot see or smell radon, so testing your home is the only way to know your level. If levels are high, a contractor can lower them.
Radon is an invisible, odorless radioactive gas that comes from the ground.
It is the second leading cause of lung cancer in the United States, after smoking.
The only way to know your home's radon level is to test for it.
If levels are high, a radon reduction system can lower them, usually at reasonable cost.
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The full explanation.
The simple version
Radon is a gas you cannot see, smell, or taste. It forms naturally in the ground and can seep into homes, where it can build up in the air.
Breathing in radon over many years can cause lung cancer. In fact, radon is the second leading cause of lung cancer in the United States, after smoking.
Because you cannot sense radon, testing your home is the only way to know if it is a problem.
Where radon comes from
Radon comes from uranium, a natural element in soil and rock. As uranium slowly breaks down, it releases radon gas.
Outdoors, radon spreads out in the air and is not a concern. The problem starts when radon seeps into buildings through:
- Cracks in floors and walls
- Gaps around pipes
- Openings in the foundation
Once inside, radon can build up, especially in lower levels like basements. It can be found in any type of home, new or old, with or without a basement.
How radon causes cancer
Radon is radioactive, which means it gives off small amounts of energy called radiation. When you breathe in radon, tiny radioactive particles can settle in your lungs.
Over the years, the radiation from these particles can damage the cells lining your lungs. This damage can build up and lead to lung cancer.
Radon is the leading cause of lung cancer in people who have never smoked. Unlike many risks, radon exposure is something you can test for and fix.
Radon and smoking together
Radon and smoking are a dangerous combination. Each one raises lung cancer risk on its own. Together, they raise it far more than adding the two alone would suggest.
If you smoke and your home has high radon, the risk is especially high. Lowering radon and quitting smoking both help, and doing both offers the greatest benefit.
Test your home
The only way to know your home's radon level is to test. You cannot rely on how the air feels or whether neighbors have tested.
Testing is simple and low-cost:
- You can buy a do-it-yourself test kit and follow the instructions.
- You can hire a qualified radon professional to test for you.
Radon is measured in units called picocuries per liter, or pCi/L. Higher numbers mean more radon. Health agencies suggest taking action if levels reach a certain point, and your test kit or contractor can explain the results.
What to do about high levels
If your test shows high radon, do not panic. High levels can be lowered.
A qualified contractor can install a radon reduction system. This usually means a vent pipe and fan that draw radon from under the home and release it outside, before it can build up indoors. These systems are often affordable and work well.
Sealing cracks in the foundation can also help, though it usually works best combined with a reduction system. Testing and, if needed, fixing radon is a practical way to protect your family's lungs.
When to test and retest
A few situations are good reminders to test your home for radon:
- If you have never tested before, no matter how long you have lived there.
- When buying or selling a home, since radon is often part of the process.
- After major changes to your home, like finishing a basement or changing the heating system.
- Every few years, since radon levels can change over time.
Winter can be a good time to test, because homes are often closed up and radon can build up more. Follow the instructions on your test kit closely for accurate results.
A risk you can act on
What sets radon apart from many cancer risks is how manageable it is. You cannot see or smell it, but you can measure it, and if it is high, you can lower it.
Testing your home is a simple, low-cost step that can protect your family for years. If you smoke, lowering radon and quitting smoking together offer the greatest protection for your lungs. Your health care team and local health department can point you to reliable test kits, contractors, and, if it applies to you, lung cancer screening options.
Words to know
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Common questions
▸What is radon?
Radon is a radioactive gas that forms naturally when uranium in soil and rock breaks down. It has no color, smell, or taste. It can seep up from the ground into homes and other buildings, where it can build up in the air you breathe.
▸How does radon cause cancer?
When you breathe in radon, tiny radioactive particles can get into your lungs and give off radiation. Over many years, this radiation can damage lung cells and lead to lung cancer.
▸How common a cause of cancer is radon?
Radon is the second leading cause of lung cancer in the United States, after cigarette smoking. It is the leading cause of lung cancer among people who have never smoked.
▸How do I know if my home has radon?
You cannot see or smell radon, so testing is the only way to know. Test kits are low-cost and easy to use, or you can hire a professional. Testing is a good idea for any home, no matter how new or old.
▸What if my radon level is high?
If your level is high, a qualified contractor can install a radon reduction system. This usually involves a vent pipe and fan that pull radon from under the home and release it outside. It is often affordable and works well.
▸Does smoking make radon worse?
Yes. Radon and smoking together raise lung cancer risk much more than either one alone. If you smoke and also have high radon at home, lowering both is especially important.
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