Smoke inhalation damages the body by simple asphyxiation (lack of oxygen), chemical irritation, chemical asphyxiation, or a combination of these.
Simple asphyxiants
Combustion can simply use up the oxygen near the fire and lead to death when there is no oxygen for a person to breathe.
Smoke itself can contain products that do not cause direct harm to a person, but they take up the space that is needed for oxygen. Carbon dioxide acts in this way.
Irritant compounds
Combustion can result in the formation of chemicals that cause direct injury when they contact the skin and mucous membranes.
These substances disrupt the normal lining of the respiratory tract. This disruption can potentially cause swelling, airway collapse, and respiratory distress.
Examples of chemical irritants found in smoke include sulfur dioxide, ammonia, hydrogen chloride, and chlorine.
Chemical asphyxiants
A fire can produce compounds that do damage by interfering with the body’s oxygen use at a cellular level.
Carbon monoxide, hydrogen cyanide, and hydrogen sulfide are all examples of chemicals produced in fires that interfere with the use of oxygen by the cell during the production of energy.
If either the delivery of oxygen or the use of oxygen is inhibited, cells will die.