A radioactive gas that gets trapped in indoor spaces accounts for 3 to 14 percent of all lung cancers – and our toenails could reveal our long-term exposure to this gas. Radon , a colorless and odorless gas, is the second-leading cause of lung cancer after tobacco smoking, and yet non-smokers and occasional smokers often do not qualify for a lung cancer screening. A team of scientists from the University of Calgary in Canada have found a surprisingly simple way to detect a person's long-term