Which two respiratory hazards are responsible for the majority of fire-related fatalities?

The choice highlighting carbon monoxide and hydrogen cyanide as the primary respiratory hazards linked to fire-related fatalities is accurate due to the toxic nature of these substances in smoke produced by fires.

Carbon monoxide is a colorless, odorless gas that results from incomplete combustion of carbon-containing materials. It binds to hemoglobin in red blood cells much more effectively than oxygen, leading to reduced oxygen transport throughout the body. This can cause symptoms ranging from fatigue and confusion to loss of consciousness and death, especially in enclosed spaces where smoke accumulates.

Hydrogen cyanide is another highly toxic compound that can be generated during the combustion of nitrogen-containing materials such as plastics and synthetic fabrics. It disrupts cellular respiration by inhibiting the body's ability to utilize oxygen, leading to rapid respiratory failure and potential mortality.

Both of these gases are commonly found in the smoke produced by structure fires and pose immediate and severe health risks to individuals exposed to fire environments. The lethality of both gases significantly contributes to fire-related fatalities, making them critical considerations in firefighting and safety training.