Toxic effects of polyvinyl-chloride (9002862) (PVC) on firefighters are reviewed. Hydrogen-chloride (7647010) is released by the thermal degradation of PVC, a common material in electrical wiring insulation, and plastics. Smoke is a suspension of small particles in hot air and gases. The particulate fraction consists of carbon (7440440) and particles coated with combustible products such as organic acids and aldehydes. Carbon-monoxide (630080) and carbon-dioxide (124389) are always present and constitute the bulk of the gaseous fraction. However a wide variety of other toxic gases such as phosgene (75445), benzene (71432), toluene (108883), xylene (1330207), naphthalene (91203), and vinyl-chloride (75014) are present. The toxic effects of these gases are small when compared to the toxicity of hydrogen-chloride. The synergistic effects of these gases is unknown. On entering the lungs many of these agents react with water to produce strong acids and alkalis. A violent inflammatory response occurs causing destruction of lung tissue. Many plastics produce large volumes of pulmonary irritant gases when burned. The firefighter is at fatal risk if he does not know that plastic covered cable is involved in a fire. The period just after the fire is extinguished, called the overhaul phase, is hazardous. Toxic smoke and fumes are still being emitted. This is the period in which toxic gas inhalation occurs since many firefighters remove their self contained breathing apparatus. Another hazard occurs when concrete retains heat and releases fumes throughout the overhaul phase. Exposure to many of these degradation products may not produce symptoms for up to 6 hours after the fire. Treatment after the onset of symptoms is usually ineffective. The authors suggest the mandatory use of breathing apparatus, control of hazardous building designs, use of protective masks during over haul phase, and use of air sampling techniques as preventive measures in reducing hazards for firefighters.