What level of carboxyhemoglobin (COHb) in the body is generally considered fatal?

A level of carboxyhemoglobin (COHb) of 50% or greater in the body is generally considered to be fatal because at this concentration, the ability of blood to carry oxygen is severely compromised. Carbon monoxide binds to hemoglobin over 200 times more effectively than oxygen, which means that even at lower concentrations, symptoms of poisoning can occur, including headache, dizziness, and confusion. However, at around 50% COHb, the likelihood of unconsciousness and death increases significantly due to a critical reduction in oxygen delivery to vital organs, such as the brain and heart. As COHb levels rise beyond this point, cellular functions cease, leading to hypoxia and ultimately death if not treated immediately. Understanding these thresholds is essential for fire investigators in evaluating the circumstances surrounding fire incidents and assessing potential victims of carbon monoxide poisoning.