Even a small amount of cigarette exposure can cause permanent genetic damage to the lungs that could lead to lung cancer. The risk of getting lung cancer in someone who has ever smoked, even a small amount, will always be at least slightly higher than for someone who has never smoked. Even non-smokers who are exposed to cigarette smoke at home or at work (secondhand smoke) are at increased risk for lung cancer, although certainly nowhere near as great a risk as for those who smoke heavily.