[troutman]

http://www.cancer.gov/about-cancer/c...don-fact-sheet

Cigarette smoking is the most common cause of lung cancer. Radon represents a far smaller risk for this disease, but it is the second leading cause of lung cancer in the United States. Scientists estimate that 15,000 to 22,000 lung cancer deaths in the United States each year are related to radon.

Exposure to the combination of radon gas and cigarette smoke creates a greater risk of lung cancer than exposure to either factor alone. The majority of radon-related cancer deaths occur among smokers. However, it is estimated that more than 10 percent of radon-related cancer deaths occur among nonsmokers.


http://www.hc-sc.gc.ca/ewh-semt/radi...eng.php#health


On average, 16% of lung cancer deaths are attributable to radon exposure in Canada. In 2006, an estimated 1,900 lung cancer deaths in Canada were due to radon exposure. Radon is the 2nd leading cause of lung cancer, after smoking.

Other than lung cancer, there is no evidence that radon exposure causes other harmful health effects such as any other form of cancer, respiratory diseases such as asthma, or symptoms such as persistent coughing or headaches.

Q. I am a smoker. Does radon affect me more than a non-smoker?

A. Yes. The risk from radon exposure for a smoker (including those exposed to second hand smoke) is much greater than for a non-smoker. For example, if you are a lifelong smoker but are not exposed to radon, your risk of getting lung cancer is one in ten. If you add exposure to a high level of radon, your risk becomes one in three. On the other hand, if you are a non-smoker, your lifetime lung cancer risk at the same high radon level is only one in twenty.