What Is Radon?

Radon is a radioactive gas you can't see, feel, taste, or smell. It starts out as uranium, a heavy metal found in the ground and most rocks on the planet. When uranium decays, it turns into another metal called radium. When radium breaks down, it becomes radon.

Radon gas leaves the soil and becomes part of the air and water. It can be in the air around you, but it’s usually in very small amounts that aren't harmful.

Large amounts of radon cause health problems. Even though it's a natural gas that comes from the earth, it can be toxic if you breathe in a lot of it over a long time. But there are some reliable ways you can keep your exposure low.

How does radon affect your health?

When you breathe in radon, it gets into the lining of your lungs and gives off radiation. Over a long time, that can damage the cells there and lead to lung cancer.

Radon is the second biggest cause of lung cancer after cigarette smoking. If you breathe a lot of radon and smoke, your chance of getting lung cancer is very high.

Some research has linked radon to other kinds of cancer, like childhood leukemia, but the evidence for that isn’t as clear.

What are the symptoms of radon exposure?

Unlike with other gases like carbon monoxide, you won’t have symptoms of radon poisoning right away. Instead, health problems from the exposure, such as lung cancer, show up after many years.

Lung cancer may start as a nagging cough, shortness of breath, or wheezing that doesn't go away. Other symptoms include coughing up blood, having chest pain, or losing weight without trying. If you notice any of these symptoms, call your doctor.

There are no routine medical tests that can tell you if you’ve breathed in too much radon. And no treatments will clear it from your body. But if you think you may have been exposed, talk to your doctor about whether you should have tests to check for signs of lung cancer.


How are you exposed to radon?

Buildings, like your home, school, or office, are built into the ground. If there are cracks in floors or walls, or small openings for pipes or wires that aren't fully sealed, radon can escape the soil and get indoors. Though it can get trapped in any enclosed area, radon levels are often highest in basements and crawl spaces because they're closest to the ground.

Some building materials, like concrete and wallboard, are made from natural substances that give off radon. So are granite countertops. But the amount these sources give off is mostly low. They might raise the radon level in your home, though not likely to dangerous levels.

Your job may put you in contact with radon, especially if you work underground, or with phosphate fertilizers.

Radon is also in water that comes from lakes, rivers, and reservoirs, but most of it is released into the air before the water gets to you. If your home's water supply comes from a well or another groundwater source, it may have more radon than water from a treatment facility.

How can I protect myself?

You can test your home or office with a radon kit. Some will measure levels for a few days, and others can gather the data for at least 3 months. You leave a small measuring device in a room, and then send it to a lab. You can also hire a professional to test your home or workplace for you. The Environmental Protection Agency website has a list of approved contractors in each state.

Radon is measured in picocuries. Anything higher than 4 picocuries, or 4 pCi/L, requires action. If you get these results, run another short- or long-term test to be sure. If the levels are still high, contact a certified professional about making repairs to your home or office. This may include sealing cracks or installing a ventilation system so radon doesn’t get trapped indoors.

WebMD Medical Reference Reviewed by Melinda Ratini, DO, MS on February 7, 2018



World Nuclear Association: "What is Uranium? How Does it Work?"

Agency for Toxic Substances & Disease Registry: "Public Health Statement for Radium," “ToxFAQs for Radon.”

American Lung Association: "Radon."

American Cancer Society: "Radon and Cancer."

CDC: "Radon in the Home."

Mayo Clinic: "Lung cancer."

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