Chronic obstructive pulmonary disease (COPD) is a chronic, progressive condition characterized by coughing, wheezing and shortness of breath that can drastically restrict daily activities.

COPD is closely associated with smoking. According to the American Lung Association (ALA), smokers are 12 to 13 times more likely to die from COPD than non-smokers. The ALA also estimates that 80 to 90 percent of COPD deaths are caused by smoking. Second-hand smoke exposure has also been linked to the disease.

Besides smoking, COPD is also associated with exposure to environmental pollutants and organic substances, such as fertilizer. Rarely, COPD may be caused by a genetic deficiency in the protein alpha-1 antitrypsin. Studies have also shown that low levels of alpha-1 antitrypsin coupled with known risk factors such as smoking are particularly dangerous.

Although asthma is a respiratory ailment that may resemble COPD, it is not related to COPD. Both asthma and COPD make breathing more difficult. However, asthma is usually associated with inflammation and is not capable of causing the severe and permanent damage associated with COPD. Asthma and COPD do coexist in some individuals, though the two conditions are usually treated separately. People with asthma and COPD are often more sensitive to airborne irritants and allergens.

Patients with COPD usually have one of two pulmonary diseases: bronchitis or emphysema. Although these conditions are generally linked with COPD, they should not be confused with the disease. These two conditions often coexist in individuals with COPD.

Chronic bronchitis is a condition in which the breathing passages to and from the lungs (bronchioles) have become irritated, decreasing air flow and resulting in greater mucus production. This situation leaves the lungs at greater risk of infection.

Emphysema is a condition in which the air sacs in the lungs (alveoli) are damaged, interfering with the normal exchange of oxygen and carbon dioxide. Some of them eventually collapse. Thus, a single, large useless hole (a bulla) takes the place of the many functional sacs (alveoli) that had been supporting the airways (bronchioles). This makes it harder to exhale stale air from the lungs and inhale a full breath of clean air.

Because COPD involves lung damage that gradually occurs over many years, the condition is most common in patients over the age of 60. It also occurs more often in women. In addition, women are more likely to visit a hospital emergency room for COPD, require hospitalization for COPD and die from COPD. Children do not develop the condition.

According to the ALA, COPD is consistently among the five leading causes of death in the United States. The U.S. Centers for Disease Control and Prevention (CDC)  estimate that approximately 10 million adults were diagnosed with COPD in the United States in the year 2000, and as many as 24 million may be affected. It is also responsible for more than 1 million emergency room visits every year.

Currently, there is no cure for COPD. Because the disease is a chronic, progressive condition, physicians usually strive to manage the disease in close partnership with the patient. It is essential that smoking is discontinued and medications and therapy be closely adhered to. As the disease worsens, patients are at risk of experiencing acute episodes of COPD, accompanied by breathlessness, lack of oxygen, severe coughing and other symptoms. An acute episode will usually require hospitalization.