Chronic obstructive pulmonary disease (COPD) is a lung disease that causes breathing difficulty, cough, mucus (sputum) production, and wheezing). COPD is typically caused by long-term exposure to irritating gases or particulate matter, most often from cigarette smoke. Other irritants that can cause COPD include cigar smoke, secondhand smoke, pipe smoke, air pollution, and workplace exposure to dust, smoke, or fumes. In about 1% of people with COPD, the disease results from a genetic disorder that causes low levels of a protein called alpha-1-antitrypsin (AAt). People with COPD are at increased risk of developing heart disease, lung cancer, and other conditions.
The main cause of COPD in developed countries is tobacco smoking. In the developing world, COPD often occurs in people exposed to fumes from burning fuel for cooking and heating in poorly ventilated homes). However, only some chronic smokers develop clinically apparent COPD, although many smokers with long smoking histories may develop reduced lung function. Other risk factors for COPD include a history of childhood respiratory infections, smoke exposure from coal or wood-burning stoves, exposure to secondhand smoke, and exposure to certain types of dust and chemicals at work.
In summary, the main causes of COPD are long-term exposure to lung irritants like tobacco smoke or chemicals, and air pollution).