Smoking is one of the worst things that people voluntarily do to destroy their health. More than 400-thousand Americans--and three million people worldwide--die each year from smoking-related deaths. That's more than the total number of Americans killed in World War I, Korea, and Vietnam combined. Smoking increases the risk of heart disease, which is the number-one killer of both men and women in the U-S and is responsible for 30 percent of cancer deaths. If you smoke a pack a day or more, you have two-and-a-half times the risk of a heart attack and a lung cancer risk rate 12 to 25 times greater than a nonsmoker's. Cigarette smoking is also by far the most common cause of chronic bronchitis, emphysema, and other chronic obstructive pulmonary diseases, which are the fourth-leading cause of death in the U-S. Smoking also contributes to cancers of the lung, mouth, throat, esophagus, larynx, pancreas, stomach, kidney, bladder, breast, and prostate. Cigarette tar contains more than 4,000 known chemicals, 60 of which are known to cause cancer. Stroke, osteoporosis, and glaucoma are three more medical conditions caused, or worsened, by tobacco. People who use tobacco also have twice the amount of peptic ulcer disease and higher rates of asthma, allergies, gum disease, headaches, and coughs. Even if you don't smoke, your health can be affected just by being around a smoker. About 3000 nonsmokers die of lung cancer each year from secondhand smoke.