Smoking is unhealthy because it is bad for the lungs, heart and mouth. Tobacco products and even secondhand smoke can cause cancer. People with asthma are especially affected by secondhand smoke, it makes an asthma attack worse.

Smoking is bad for the lungs because it can cause lung cancer. "The risk of developing lung cancer is about 23 times higher among men who smoke cigarettes and about 13 times higher among women who smoke cigarettes compared with non smokers."

Smoking is also bad for the heart because it can cause heart disease.

  • "Cigarette smoking causes coronary heart disease, the leading cause of death in the United States. Cigarette smokers are 2–4 times more likely to develop coronary heart disease than nonsmokers.
  • "Cigarette smoking approximately doubles a person's risk for stroke.
  • "Cigarette smoking causes reduced circulation by narrowing the blood vessels (arteries). People who smoke have a much greater risk of developing peripheral vascular disease than nonsmokers.
  • "Smoking causes abdominal aortic aneurysm.
  • "Secondhand smoke exposure causes heart disease and lung cancer in nonsmoking adults.
  • "Nonsmokers who are exposed to secondhand smoke at home or work increase their heart disease risk by 25–30% and their lung cancer risk by 20–30%.
  • "Breathing secondhand smoke has immediate harmful effects on the cardiovascular system that can increase the risk of heart attack. People who already have heart disease are at especially high risk."

Smoking can cause other types of cancer as well.

  • "Cigarette smoking increases the risk for many types of cancer, including cancers of the lip, oral cavity, pharynx, esophagus, pancreas, larynx (voice box), lung, uterine cervix, urinary bladder, and kidney."

Healthy lungs

Healthy heart

Unhealthy heart