In addition to the addictive drug nicotine, the other principal harmful substances in cigarettes are tar and carbon monoxide. Tar is a sticky, brown residue that collects in the lungs. Primarily made up of chemicals known as hydrocarbons, tar is a powerful cancer-causing agent that has been linked to the development of lung cancer. Carbon monoxide is a poison that partially replaces the oxygen normally carried throughout the body by red blood cells, robbing the body of sufficient oxygen. Switching to a low-tar cigarette usually does not help because the person
usually compensates for the change by inhaling longer or by smoking more cigarettes. Other toxic chemicals in tobacco smoke include arsenic, formaldehyde, ammonia, lead, benzene, and vinyl chloride. The airways try to fight these poisons by producing excess mucus, which obstructs the airways, producing the telltale smoker’s cough that indicates the development of chronic bronchitis. Tobacco smoke damages not only the cells inside the lungs but also the tiny hairlike projections called cilia that line and protect the airways, hindering the respiratory system’s ability to fight infection. Smoke inflames lung tissue, causing the airways to release chemicals that destroy the tiny air sacs in the lungs called alveolar, where oxygen is transferred into the bloodstream. The alveoli
merge into fewer but larger air sacs, reducing the surface area in the lungs available for oxygen transfer. Because the level of oxygen in the blood is reduced, the affected person becomes breathless. This process describes the development of the disease known as emphysema.
Cigarette smoking causes cancer of the lung, mouth, tongue, throat, pancreas, kidney, and bladder by producing cell changes that cause the cells to reproduce uncontrollably. Smoking is responsible for about 87 percent of all cases of lung cancer in the United States. Most lung cancers begin in a bronchus, one of the
two main air passages that enter the lungs. Smoking also is a major contributor to the development of heart disease, by reducing blood levels of high-density liposuction (HDL), the “good” cholesterol that protects against heart disease. Additionally, smoking adversely affects the arteries that supply the heart with blood and nutrients. Men who smoke have twice the risk of having a heart attack as do nonsmoking men.
Nonsmokers exposed to secondhand smoke also endure an increased risk of heart disease. Up to 30 percent of all deaths from heart disease in the nation can be attributed to cigarette smoking, and the risk increases with the number of cigarettes smoked and the number of years of smoking. Smoking cigarettes also doubles your risk of having a stroke. In spite of the dire health prospects facing smokers, many of them continue their habit because of nicotine’s addictive properties. But if you smoke, effective methods exist to help you quit and avoid starting again.
