Because cigarette smoking uses inhalation as its nicotine delivery system, the lungs and bronchi, or the airways leading to the lungs, sustain the most damage. Any restriction to the airways or the blood vessels that serve the lungs hampers lung function. Smoking harms humans by increasing blood pressure and reducing oxygen loads, so that the transfer of oxygen from the lungs to the circulatory system becomes less efficient. Over time, tobacco users may experience a progression of health problems associated with breathing.
Functional Decline
The Centers for Disease Control and Prevention (CDC) report that adult and adolescent smokers suffer the type of reduced lung function that usually accompanies advanced aging. Lungs weakened by tobacco use are more susceptible to bacterial and viral infections.
The damage to lungs may result in scarring of tissue from smoke contact or from recurrent infections, such as a pneumonia. Scar tissue impedes lung function and gives rise to progressive breathing health problems.
Chronic Bronchitis
Chronic bronchitis is one form of chronic obstructive pulmonary disease (COPD), a lung disease caused by persistent cigarette smoking. Its main symptom is a "smoker's cough" that may be present on most days for extended periods, according to the American Lung Association. The breathing obstruction created by this health problem can be fatal.
Damage to the lungs from smoke exposure causes excess mucus to be produced by the bronchi. The bronchial cilia, filaments that normally clear away mucus and dirt, can be paralyzed or disabled by cigarette smoking. When the cilia are unable to move mucus up and out of the airways, a cough develops to perform this function.
Emphysema
Emphysema is the advanced form of COPD, a health problem that is incurable and potentially fatal. More severe coughing, wheezing and shortness of breath--especially reduced outward airflow--may indicate emphysema.
Johns Hopkins Medicine reports that the lung alveoli, or air sacs that fill with oxygen and carbon dioxide, are specifically damaged through long-term tobacco use. They become enlarged and brittle, and are less efficient at expelling air from the lungs. Holes or scars that form in the lungs from emphysema are irreversible.
Cancer
Cigarette smoking causes lung cancer. Nicotine and more than 60 other carcinogens in cigarette smoke alter the body's cellular DNA. The American Cancer Society relates that lung cells can form cancerous tumors, some of which may spread to other parts of the body.
About 85 percent of lung cancer fatalities occur in smokers, the CDC notes. Individual risk for lung cancer increases, along with the number of cigarettes smoked and the number of years of tobacco use. Quitting smoking has the adverse effect of reducing lung cancer risk.
