Hi weirdo...Maybe this will help make it a bit clearer...

Oxford University, cataloged the causes of cancer in the United States. They calculated that smoking accounted for more than 87 percent of all cancer deaths and that pollution was associated with about 2 percent of all cancers. The EPA agrees.

Lung cancer is the leading cause of cancer deaths in the United States, among both men and women. It claims more lives than colon, prostate and breast cancer combined. Since the mid-1990s, more than 150,000 Americans have died of the disease each year.

Yet most of these deaths could have been prevented. That's because smoking accounts for about 85 percent to 90 percent of lung cancer cases.

http://www.mayoclinic.com/invoke.cfm?id=DS00038

http://www.lungusa.org/site/pp.asp?c=dvLUK9O0E&b=35427