"Popcorn lung" is a colloquial term for a condition called bronchiolitis obliterans, which damages the small airways in the lungs. It is associated with exposure to diacetyl, a chemical used in artificial butter flavoring for popcorn and other foods. Inhalation of diacetyl can lead to scarring of the lung tissue, resulting in coughing, wheezing, and shortness of breath. The condition gained attention in the early 2000s when workers at a microwave popcorn plant developed severe respiratory issues. Although the use of diacetyl in food products has decreased, concerns remain about its presence in e-cigarettes and other inhaled products.