Cigarette smoking is the leading contributor to preventable deaths in the United States. Smoking can result in chronic conditions that affect the heart, circulatory and respiratory systems, contributing or causing more than 25 specific diseases, according to the Surgeon General.

Smokers face a much higher risk of life-threatening events such as heart attack and stroke. Tobacco use is blamed for more than 437,000 deaths each year from all causes, including heart attack and stroke, according to the American Heart Association’s Heart Disease and Stroke Statistics – 2007. About 34 percent of these deaths were cardiovascular related.

Nonsmokers are also at risk. Experts estimate that a nonsmoker who is exposed to secondhand (or slipstream) tobacco smoke (at work or in the home) faces a 30 percent higher risk of coronary artery disease than someone not exposed to secondhand smoke. About 35,000 nonsmokers are estimated to die every year from smoking-related coronary artery disease.

Besides the human toll, smoking carries a hefty economic price. Medical costs for smoking-related conditions exceed $157 billion annually in the United States. Worldwide, the magnitude of this problem is even greater – smoking causes or contributes to 3.5 million deaths every year.

Cigarette smoking can make otherwise uncommon medical problems more likely. Lung cancer, for instance, was rarely encountered up to the early 20^th century. By the 1930s (about 40 years after mass-produced cigarettes appeared on the market) physicians began seeing an increase in the number of lung cancer cases.

In 1950, the landmark study by British doctors Richard Doll and Austin Hill concluded that cigarette smoking is an “important factor” in the production of lung cancer. The research was widely publicized and sparked anti-smoking campaigns around the world. In 1964, a report by the U.S. Surgeon General acknowledged the connection between smoking and cancer. A second Surgeon General report in 1988 stated that nicotine and tobacco produce addiction levels similar to heroin or cocaine.

Every Surgeon General’s report since then had added to the list of disease caused by smoking. Today, in addition to lung cancer, heart disease, chronic obstructive pulmonary disorder and stroke, smoking has been linked to:

• Abdominal aortic aneurysm
• Leukemia
• Cataract
• Cancer of the cervix, kidney, pancreas, stomach, bladder, esophagus, larynx and throat
• Pneumonia
• Gum disease
• Sudden infant death syndrome (SIDS)

Researchers have estimated that smoking cuts an average of 10 years off a person's life expectancy, even with advances in prevention and treatment of the various diseases associated with smoking. However, by quitting early these “lost” years can be regained. A person who quits at age 35 can live as long as nonsmokers, according to recent studies.