2ndhand smoke, etc. The chief cause of lung cancer is long-term exposure to tobacco smoke. Nonsmoker cases are from a combination of genetic factors, radon gas, asbestos, and air pollution including secondhand smoke. Asbestos can also cause mesothelioma, a cancer of the pleura or lining on the surface of the lung and diaphragm. So a combo. Of pollution, smoking and other factors likely causes urban lung disease.