Cigarette smoke is a toxic mixture of more than 7,000 chemicals, many of which may cause cancer and other diseases. These poisonous chemicals enter the lungs, then the bloodstream, which carries them throughout the body, resulting in immediate injury to the blood vessels and tissues. With continued smoking, your tissues incur damage, and your immune system works overtime, fighting to heal the damage. This vicious cycle of cell damage and the immune system's response disrupts health and promotes all kinds of serious illnesses, including heart disease, multiple types of cancer and a long list of other illnesses.
Atherosclerosis, Heart Disease and Stroke
Smoking causes atherosclerosis, a disease of the blood vessels that begins with damage to the inner lining of the artery wall. Your body's attempt to heal the damage results in the formation of hard plaques inside your arteries. Eventually, atherosclerosis can disrupt the healthy flow of blood to your heart, brain and other organs and tissues, increasing your risk of developing heart disease and stroke. Atherosclerotic heart disease is the leading cause of death for men and women in the United States. People who smoke are 2 to 4 times more likely to develop heart disease than nonsmokers, according to the Centers for Disease Control and Prevention.
Cancer and Lung Disease
Smoking is the leading cause of lung cancer. According to a report from the surgeon general in 2014, nearly 90 percent of all lung cancer deaths are attributable to smoking. Smoking also increases your likelihood of cancer in other body areas, including your head, neck, breasts, pancreas, kidneys, cervix, bladder, colon and rectum. It can even increase your risk of developing leukemia. Smoking causes chronic obstructive pulmonary disease, or COPD, a disorder that includes emphysema and chronic bronchitis. People who smoke are 12 times more likely to die from COPD than nonsmokers, according to the CDC.
Other Health Risks
Smoking causes or has been implicated in the development of a huge variety of other diseases, including type 2 diabetes. People who smoke have a 30 percent to 40 percent higher risk for diabetes than nonsmokers, according to the 2014 surgeon general’s report. Smoking reduces fertility in both men and women and causes erectile dysfunction in men. Women who smoke are at increased risk for pregnancy complications including miscarriage, preterm delivery and birth defects. Smoking contributes to gum disease, leading to tooth loss, and it affects eye health, increasing your chances of cataracts and blindness. It also promotes lung and other infections, contributes to weakened bones in post-menopausal women, and increases your risk of complex diseases like rheumatoid arthritis.
Risks From Light Smoking and Secondhand Smoke
Cutting down on the amount you smoke may be a step in the right direction, but there is no safe level of cigarette smoke. According to a study reported in the October 2005 issue of "Tobacco Control," smoking just 1 to 4 cigarettes per day is associated with a sharp increase in the risk of death. Even secondhand exposure can shorten your life. In 2006, the surgeon general reported that any level of exposure to cigarette smoke is harmful. This includes secondhand exposure, which can have immediate negative effects and lead to heart disease and lung cancer. About 3,400 nonsmoking adults die of lung cancer each year as a result of breathing secondhand smoke, according to the 2014 surgeon general’s report.