Particulate matter air pollution exposure: role in the development and exacerbation of chronic obstructive pulmonary disease

Due to the rapid urbanization of the world population, a better understanding of the detrimental effects of exposure to urban air pollution on chronic lung disease is necessary. Strong epidemiological evidence suggests that exposure to particulate matter (PM) air pollution causes exacerbations of pre-existing lung conditions, such as, chronic obstructive pulmonary disease (COPD) resulting in increased morbidity and mortality. However, little is known whether a chronic, low-grade exposure to ambient PM can cause the development and progression of COPD. The deposition of PM in the respiratory tract depends predominantly on the size of the particles, with larger particles deposited in the upper and larger airways and smaller particles penetrating deep into the alveolar spaces. Ineffective clearance of this PM from the airways could cause particle retention in lung tissues, resulting in a chronic, low-grade inflammatory response that may be pathogenetically important in both the exacerbation, as well as, the progression of lung disease. This review focuses on the adverse effects of exposure to ambient PM air pollution on the exacerbation, progression, and development of COPD.