The killing fumes
Most fire deaths are not caused by burns, but by smoke inhalation. Often smoke incapacitates so quickly that people are overcome and can’t make it to an otherwise accessible exit. The synthetic materials commonplace in today’s homes produce especially dangerous substances. As a fire grows inside a building, it will often consume most of the available oxygen, slowing the burning process. This “incomplete combustion” results in toxic gases.
Smoke is made of components that can each be lethal in its own way:
particles: Unburned, partially burned, and completely burned substances can be so small they penetrate the respiratory system’s protective filters, and lodge in the lungs. Some are actively toxic; others are irritating to the eyes and digestive system.
vapors: Foglike droplets of liquid can poison if inhaled or absorbed through the skin.
toxic gases: The most common, carbon monoxide (CO), can be deadly, even in small quantities, as it replaced oxygen in the bloodstream. Hydrogen cyanide results from the burning of plastics, such as PVC pipe, and interferes with cellular respiration. Phosgene is formed when household products, such as vinyl materials, are burned. At low levels, phosgene can cause itchy eyes and a sore throat; at higher levels it can cause pulmonary edema and death.
In addition to producing smoke, fire can incapacitate or kill by reducing oxygen levels, either by consuming the oxygen, or by displacing it with other gases. Heat is also a respiratory hazard, as superheated gases burn the respiratory tract. When the air is hot enough, one breath can kill.
(Provided by NFPA)