Polymer fume fever usually occurs as a self-limited systemic illness with only minor pulmonary symptoms. Like metal fume fever, constitutional signs and symptoms typically present several hours after initial exposure, often giving rise to a misdiagnosis of viral "flu." Compared to metal fume fever, polymer fume fever has a more varied clinical presentation, the severity of which depends upon the specific conditions of exposure. When higher temperatures and/or longer durations of exposure are involved, significant pulmonary involvement, including radiographic consolidation, is a potential complication. Although a number of industrial outbreaks have implicated the smoking of contaminated cigarettes as a vehicle of exposure, any industrial or household activity in which PTFE is heated above 350-400 degrees C puts nearby workers or residents at risk of illness and is to be avoided without strict industrial hygiene controls.