Second-hand smoking
The inhalation of smoke from the environment, known as passive or second-hand smoking, can increase the chances of lung cancer among individuals who are not active smokers. The smoke inhaled by the individuals who live with smokers and from the environment. These individuals have 24% more risk of lung cancer than those who do not live with smokers. The risk increased by the level of exposure to the smoke, i.e., the number of cigarettes smoked per day and the number of years of smoking.