COPD Resources What is COPD? COPD Facts Causes of COPD Diagnosing COPD COPD vs. Asthma The Lungs Current Treatments Patient Information Causes of COPD Cigarette, Pipe, cigar and other types of tobacco smoking[3] Passive exposure to cigarette smoking[3] Occupational dusts and chemicals[3] Air pollution[3]; and Genetic factors (less than 5 percent of cases).[11]		Cigarette smoking is the leading cause of COPD and has been implicated in 80 percent to 90 percent of cases.[11]