Chronic lower respiratory disease, primarily COPD, was the third leading cause of death in the United States in 2014. Almost 15.7 million Americans (6.4%) reported that they have been diagnosed with COPD. More than 50% of adults with low pulmonary function were not aware that they had COPD, so the actual number may be higher. With COPD, the airways in your lungs become inflamed and thicken, and the tissue where oxygen is exchanged is destroyed. The flow of air in and out of your lungs decreases. When that happens, less oxygen gets into your body tissues, and it becomes harder to get rid of the waste gas carbon dioxide. As the disease gets worse, shortness of breath makes it harder to remain active. The most common cause of COPD is tobacco smoking, with a smaller number of cases due to factors such as air pollution and genetics. In the developing world, common sources of air pollution are wood combustion and cooking fires. As of 2015, COPD affected about 174.5 million people (2.4% of the global population). It typically occurs in people over the age of 40. Males and females are affected equally commonly. In 2015, it caused 3.2 million deaths, more than 90% in the developing world up from 2.4 million deaths in 1990. The number of deaths is projected to increase further because of higher smoking rates in the developing world, and an aging population in many countries. It resulted in an estimated economic cost of US$2.1 trillion in 2010.

The pooled COPD prevalence among Bangladeshi adult was 12.5% (95% CI, 10.9-14.1) using the Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria and 11.9% (95% CI, 11.4-13.6) using the lower limit of the normality (LLN) criteria. The prevalence was higher among males, low socio-economic group, rural residents, and biomass fuel users. Tobacco consumption, exposure to biomass fuel, old age, and history of asthma were identified as major risk factors of COPD. COPD prevalence is high in Bangladesh.