While cigarette smoking is an undisputed cause of lung cancer, not all cases of lung cancer occur in smokers or former smokers. Each year, over 170,000 Americans develop lung cancer, and approximately ten per cent of lung cancers, or 17,000 cases, occur in non-smokers. Although not every non-smoker suffering from lung cancer will have an identifiable risk factor for development of the disease, a number of conditions and circumstances have been identified that will increase a non-smoker’s chance of developing lung cancer.
- Passive smoking, or the inhalation of tobacco smoke from other smokers sharing living or working quarters, is an established risk factor for the development of lung cancer. Non-smokers who reside with a smoker have a 24% increase in risk for developing lung cancer when compared with other non-smokers. Each year, up to 3,000 lung cancer deaths are estimated to occur in the U.S. that are attributable to passive smoking.
- Radon gas, a naturally-occurring gas that forms when uranium decays, is another known cause of lung cancer. An estimated 12% of total lung cancer deaths in both smokers and non-smokers, or 15,000 to 22,000 lung cancer-related deaths annually in the U.S, are believed to be at least partially related to radon gas exposure. Those who do smoke and are exposed to radon have an even greater risk of developing lung cancer than non-smokers who are exposed to radon gas. Radon gas can travel up through soil and enter homes through gaps in the foundation, pipes, drains, or other openings. The U.S. Environmental Protection Agency estimates that one out of every 15 homes in the U.S. contains dangerous levels of radon gas. Radon gas is invisible and odorless but can be detected with simple test kits.