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Pulmonary Disease and Smoking – Introduction
Cigarette smoking is the leading cause of health conditions affecting the LUNGS and accounts for 90 percent of LUNG CANCER in the United States. It is also the leading cause of many forms of CARDIOVASCULAR DISEASE (CVD), including HYPERTENSION, ATHEROSCLEROSIS, ISCHEMIC HEART DISEASE (IHD), CORONARY ARTERY DISEASE (CAD), and PERIPHERAL VASCULAR DISEASE (PVD).
Though the correlation between cigarette smoking and lung cancer has been known since the 1940s and widely publicized since the 1964 landmark report Smoking and Health: Report of the Advisory Committee to the Surgeon General of the Public Health Service, nearly 49 million Americans currently smoke. About one in six has at least one significant health condition that is a direct consequence of smoking. The longer a person smokes, the higher the risk for developing a smoking-related health condition.
Pulmonary Function and Smoking
The first few puffs of every cigarette paralyze the cilia, the hairlike structures that line the airways and sweep mucus from the lungs. NICOTINE from the smoke immediately passes across the alveolar membrane into the BLOOD, entering the circulation within seconds. A potent central NERVOUS SYSTEM STIMULANT and vasoconstrictor, nicotine causes smooth MUSCLE fibers to contract, contributing to cerebrovascular and cardiovascular disease such as STROKE and HEART ATTACK. Nicotine remains active in the circulation for about 20 minutes after the last puff from the cigarette, keeping the airways constricted.
One of the most hazardous chemicals in cigarette smoke is carbon monoxide, which binds more strongly with HEMOGLOBIN than oxygen. Hemoglobin molecules will not release carbon monoxide to bind with oxygen, thus carbon monoxide blocks oxygen diffusion into the blood. Carbon monoxide levels in the blood can reach 5 to 7 percent with smoking a single cigarette, dropping OXYGEN SATURATION to near 90 percent. The other byproducts of combustion from cigarette smoke can result in direct toxicity to the lungs.
Obstructive Lung Diseases
Tar and smoke particulates that enter the airways and lungs with each cigarette cause irritation and INFLAMMATION. Over time SCAR tissue replaces lung tissue as the body attempts to repair itself from repeated damage and protect itself from further damage. This scar tissue gradually destroys the alveoli and bronchioles, the lung’s smallest structures, and eventually becomes pervasive within the lungs.
The consequence is CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD), which accounts for more than 70 percent of pulmonary disease related to smoking. COPD is the leading reason for LUNG TRANSPLANTATION in the United States and is also the leading form of noncancer lung disease. Once the damage of COPD occurs, it is permanent.
Cigarette smoke contains about 4,000 identifiable chemicals, more than 60 of which are identified carcinogens (cancer-causing substances). Among them are tar, arsenic, polycyclic aromatic hydrocarbon (PAH) compounds, formaldehyde, and nitrosamines. Smoking accounts for more than 90 percent of LUNG CANCER in the United States. Among cancers, lung cancer is the leading killer of both men and women. Part of the reason the outlook is so poor for lung cancer is that by the time it shows symptoms it is fairly advanced and often has spread to other organs throughout the body.
Pulmonary Benefits of Smoking Cessation
Much, though not all, of the damage cigarette smoking does will gradually repair itself when the person no longer smokes. The rate of decline of lung function will slow, and chronic cough and sputum production often improve. Cardiovascular risk also drops significantly after smoking cessation. Risk for head and neck and lung cancers also decreases.