About half of all COPD cases worldwide are due to non-tobacco-related risk factors, which vary by geographical region. These factors include air pollution, occupational exposures, poorly controlled asthma, environmental tobacco smoke, infectious diseases, and low socioeconomic status, reveals the latest study published in The Lancet Respiratory Medicine in the first of a Series of three papers on the origins of COPD by a team of scientists from Australia and India. While impaired lung growth during childhood, caused by a range of early-life exposures, is associated with an increased risk of COPD, other potential mechanisms for the pathogenesis of COPD in never-smokers include inflammation, oxidative stress, airway remodelling, and accelerated lung ageing. Compared with smokers who develop COPD, never-smokers with COPD have relatively mild chronic respiratory symptoms, little or no emphysema, milder airflow limitation, and fewer comorbidities; however, exacerbations can still be frequent, the study observed.