Cigarette smoking is the major cause of preventable deaths in the U.S. On the average, people who smoke die 5 to 8 years earlier than people who don't smoke.

Tobacco users, and people who live with smokers, have nearly all cases of lung cancer. Their risk of developing throat, mouth, esophageal, pancreatic, kidney, bladder, and cervical cancer is several times greater than for people who are not regularly exposed to tobacco smoke. Smoking is the major cause of emphysema, a debilitating lung disease which slowly destroys a person's ability to breathe normally.

Smoking is especially hazardous for people with:

• heart disease

• blood vessel disease

• diabetes

• high blood pressure

• high cholesterol

• family history of these diseases.

Smokers, and those living with smokers, have a two times greater risk of fatal heart disease. Smoking also increases the risk of having a stroke. Women, especially those over 35 years old, who take birth control pills and smoke have an increased risk of stroke or heart attack. Increased blood pressure is another danger of smoking. Smoking also decreases HDL, or 'good cholesterol' levels.

Smokers and people living with them have a two to three times greater chance of having peptic ulcers. Smokers also have a greater than average risk of hip, wrist, and vertebral (spine) fractures. In addition, smoking complicates sleep disorders. Smokers also tend to get colds and other respiratory tract infections more often than nonsmokers.

Tobacco smoke is dangerous to nonsmokers. Exposure to the smoke, also called passive smoking, increases the risks of nonsmokers getting the same problems as smokers. A nonsmoker in a very smoky room for 1 hour with several smokers inhales as many bad chemicals as he would inhale by actually smoking 10 or more cigarettes himself. One study found that the rate of lung cancer among nonsmoking women depended on the amount their husbands smoked.

Smoking affects pregnant women and their unborn children. Smoking mothers have a greater risk of miscarriage and stillbirth. Children born to women who smoke have lower birth weights on average. They also have more frequent respiratory infections, a higher risk of chronic ear infections and asthma, and less efficient lung function. Recent research suggests possible links between maternal smoking and attention-deficit disorder (hyperactivity) in children. Investigation also continues into the possibility that cigarette smoke exposure may be a factor in SIDS (sudden infant death syndrome). Children of smokers usually become cigarette smokers themselves.

The more cigarettes a person smokes each day, the greater the risk of disease. Switching from cigarettes to a pipe or cigars may not lessen the risk of disease if you continue to inhale. Cigar and pipe smokers are at the same risk for cancers of the mouth, lip, larynx, and esophagus as cigarette smokers. Fortunately, when a smoker stops smoking many of these risks decrease.

Users of snuff or chewing tobacco ('smokeless tobacco') increase their risk of cancer of the mouth. The mouth cancer can develop relatively quickly, within 10 to 15 years of the first use of snuff or chewing tobacco.