Combustion toxicology embraces the nature, the severity, and the time course of adverse effects produced upon exposure to fire-generated toxic species. These species usually consist of narcotic toxicants or asphyxiants, along with those which may produce sensory/upper respiratory and even pulmonary irritation. They all act in concert to compromise the vital systems of those exposed, leading to incapacitation and death generally through various hypoxia-producing mechanisms. Some fire gas toxicants are material-dependent, some are largely dependent on the combustion conditions of the fire, while others may be dependent on both. Since the rates of generation of fire toxicants are powered by the energy release of the fire, the development of toxic hazard is also dependent on the fire itself.