Inhaling small amounts of smoke usually causes no serious, lasting effects. However, if the smoke contains certain poisonous chemicals or is unusually dense or if inhalation is prolonged, serious problems can develop. Even common household materials such as plastics and fabrics can produce poisonous chemicals (toxic products of combustion) when they burn.

Smoke inhalation can cause problems in several ways:  Suffocating the body with carbon monoxide,  Poisoning the body with toxic chemicals, Damaging the windpipe, breathing passages, and/or lungs from toxic chemicals,  Burning the mouth and throat from hot gases, Carbon monoxide is a gas produced in many fires. When inhaled, carbon monoxide prevents the blood from carrying oxygen so tissues do not get enough oxygen.”.

MERCK MANUAL