Methemoglobinemia occurs in fire due to heat denaturation of hemoglobin, oxides produced in fire, and methemoglobin-forming materials such as nitrites. Occurrence of methemoglobinemia is a rarer phenomenon than CN and CO toxicity. The pathophysiologic consequences of methemoglobin formation are a decrease in the oxygen-carrying capacity of the blood and a shift of the oxyhemoglobin dissociation curve to the left, similar to carboxyhemoglobin (HbCO). Pulmonary irritation Irritants can cause direct tissue injury, acute bronchospasm, and activation of the body’s inflammatory response system.
Supporting the importance of the inflammatory response to the mechanism of tissue destruction, some studies have shown that the administration of the cyclooxygenase inhibitor, ibuprofen, was found to reduce the lung lymph flow in animals with SI. The direct injury is a consequence of the size of the particle, its solubility in water, and its acid-base status. Ammonia produces alkaline injury, while sulfur dioxide and chlorine gas lead to acid injuries. Other chemicals act via different mechanisms; for instance, acrolein causes free radical formation and protein denaturation.
High-solubility substances such as acrolein, sulfur dioxide, ammonia, and hydrogen chloride cause injury to the upper airway. Substances with intermediate solubility, such as chlorine and isocyanates, cause upper and lower respiratory tract injury.
Responses to 'Smoke and Fire Safety Hood - Save Lives'