The Truth About Radon


What is radon?

Radon is a naturally occurring, cancer-causing radioactive gas. You cannot see, smell or taste radon, but it may be a problem in your home. The Surgeon General has warned that radon is the second leading cause of lung cancer in the United States today. If you smoke and your home has high radon levels, you’re at an even higher risk for developing lung cancer. Some scientific studies of radon exposure indicate that children may be more sensitive to radon.


The Environmental Protection Agency and the Surgeon General’s Office estimate that as many as 20,000 lung cancer deaths are caused each year by radon.

  • Radon is a colorless, odorless and flavorless gas at ordinary temperature and pressure. Radon is radioactive and decays into other radioactive and toxic elements.

  • Radon is present in the Earth's crust at an abundance of 4 x10-13 milligrams per kilogram. It is always present outdoors and in drinking water from natural sources, but at a low level in open areas. It's mainly a problem in enclosed spaces, such as indoors or in a mine.

  • The EPA estimates the average indoor radon concentration is 1.3 picocuries per liter (pCi/L). It has estimated that approximately 1 in 15 homes in the US has high radon, which is 4.0 pCi/L or higher.

  • Radon is the second leading cause of lung cancer overall (after smoking) and the leading cause of lung cancer in non-smokers.


Health Risks of Radon


The U.S. Surgeon General, Richard Carmona, Issues National Health Advisory

The Surgeon General of the United States issued a Health Advisory in January 2005, warning Americans about the health risk from exposure to radon in indoor air. The Nation’s Chief Physician urged Americans to test their homes to find out how much radon they might be breathing. Dr. Carmona also stressed the need to remedy the problem as soon as possible when the radon level is 4 pCi/L or more. Dr. Carmona noted that more than 20,000 Americans die of radon-related lung cancer each year.

Deaths Per Year


Studies Find Direct Evidence Linking Radon in Homes to Lung Cancer

(January 29, 2005 and March 16, 2005) Two studies show definitive evidence of an association between residential radon exposure and lung cancer. The North American study and European studies both combined data from several previous residential studies. These two studies go a step beyond earlier findings. They confirm the radon health risks — predicted by occupational studies of underground miners, who breathed radon for a period of years. Early in the debate about radon-related risks, some researchers questioned whether occupational studies could be used to calculate risks from exposure to radon in the home environment. “These findings effectively end any doubts about the risks to Americans of having radon in their homes,” said Tom Kelly, Director of EPA’s Indoor Environments Division. “We know that radon is a carcinogen. This research confirms that breathing low levels of radon can lead to lung cancer.”

Exposure to Radon Causes Lung Cancer in Non-smokers and Smokers Alike

Lung cancer kills thousands of Americans every year. The untimely deaths of Peter Jennings and Dana Reeve have raised public awareness about lung cancer, especially among people who have never smoked. Smoking, radon, and secondhand smoke are the leading causes of lung cancer. Although lung cancer can be treated, the survival rate is one of the lowest for those with cancer. From the time of diagnosis, between 11 and 15 percent of those afflicted will live beyond five years depending upon demographic factors. In many cases lung cancer can be prevented; this is especially true for radon.


Haynes, William M., ed. (2011). CRC Handbook of Chemistry and Physics (92nd ed.). Boca Raton, FL: CRC Press. p. 4.122. ISBN 1439855110
Kusky, Timothy M. (2003). Geological Hazards: A Sourcebook. Greenwood Press. pp. 236–239. ISBN 9781573564694.