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.
Asbestos is a compound that was widely used in the past as both thermal and acoustic insulation material. Microscopic fibers of asbestos break loose from the insulation material and are released into the air where they can be inhaled into the lungs. Asbestos fibers can persist for a lifetime in lung tissue following exposure to asbestos. Both lung cancer and a type of cancer known as mesothelioma are associated with exposure to asbestos. Cigarette smoking drastically increases the chance of developing an asbestos-related lung cancer among workers exposed to asbestos; nevertheless, asbestos workers who do not smoke have a five fold greater risk of developing lung cancer than other non-smokers. Today, asbestos use is limited or banned in many countries including the Unites States.