Inhalation of toxic substances in the workplace can result in a variety of respiratory disorders. One relatively rare sequela of the inhalation of toxic fumes is bronchiolitis obliterans, a condition characterized by fibrosis and narrowing of the small airways. Several substances have been reported to cause bronchiolitis obliterans, including ammonia, chlorine, hydrogen fluoride, hydrogen sulfide, nitrogen dioxide, ozone, phosgene, and other irritant fumes. Little has been reported on the pulmonary effects of fly ash produced by the incineration of coal and oil. We report a case of bronchiolitis obliterans with a component of partially reversible airway obstruction in a 39-year-old male occupationally exposed to incinerator fly ash.