Smoke grenades are used during drills, police and military exercises, and crowd control. We report on a 25-year-old man who was exposed to a Superior 3C smoke bomb. He was initially stable but developed respiratory distress after 3 days and ultimately developed pulmonary fibrosis with marked loss in pulmonary function. The Superior 3C smoke bomb is similar in composition to the British Military's L83A1/2 and L132A1 and the US M18 smoke grenades, all commonly used as multipurpose smoke-producing devices for combat and training. They are primarily composed of zinc oxide and hexachlorethane, the combustion of which produces zinc chloride. These devices are safe when used properly in open air but can cause significant morbidity in an enclosed space. This case emphasizes the potential hazards of using smoke bombs even in semienclosed spaces and the potential delay in the development of significant pulmonary complications.