Over recent years, investigators have experienced a growing appreciation for small airways disease as an occupational lung disease. Small airways disease includes a range of diagnoses such as hypersensitivity pneumonitis, mineral dust airways disease, and constrictive bronchiolitis. Novel exposures or, in certain cases, novel settings for well-established respiratory toxicants continue to be reported. Given recent reports among military personnel serving in the Middle East as well as diacetyl exposed workers employed in microwave popcorn manufacturing plants, constrictive bronchiolitis as an occupational lung disease has gained particular notoriety. The diagnosis of constrictive bronchiolitis remains challenging as plain chest radiographs may appear normal and physiologic testing may revea...