Smoking is one of the worst things you can do for your health. Secondhand smoke is also very dangerous. Nearly 7,300 nonsmoking Americans die from lung cancer caused by secondhand smoke every year, reports the Centers for Disease Control and Prevention (CDC). Smoking and secondhand smoke exposure can also cause other health conditions, such as chronic obstructive pulmonary disease (COPD), emphysema, and heart disease. They also raise your risk of developing many types of cancer.