Three cases of asthma that developed following smoke inhalation were described. It was suggested that the induction of airways hyperresponsiveness and the asthmatic state following a single high dose exposure to pyrolysis products was due to airway inflammation caused by one or more toxic inhalants. The first case involved a 34 year old white man, a fire fighter for 2 years, who was exposed to dense smoke for a few minutes in the hold of a tugboat during an on board fire. He was not wearing respiratory protective gear at the time of entry into the hold. The fire consumed wood, a few oil soaked rags, and other petroleum products, but no obvious plastics or synthetic materials. The second case involved a 38 year old white woman awakened by a residential fire that began in the refrigerator and spread throughout the apartment. The fire involved plastic laminates, plastic refrigerator components, wall coverings and synthetic drapery material. The third case involved a 28 year old Hispanic man entering a burning house to rescue a young child. He suffered burns and severe smoke inhalation causing diffuse pulmonary infiltrates and hypoxic respiratory failure. The author states that findings in such cases may be minimal immediately after exposure, and the patient may become symptomatic only after a number of days. Fire fighters and other victims of smoke inhalation share the common risks of multiple, unpredictable, and difficult to quantify exposures to toxic inhalants. Ammonia (7664417), acrolein (107028) and other aldehydes, sulfur-dioxide (7446095), nitrogen-dioxide (10102440), hydrogen-fluoride (7664393), reactive oxygen species, phosgene (75445), hydrogen-chloride (7647010), and isocyanates are often found in the pyrolysis of synthetic and natural materials.