Carboxyhemoglobin is a product of hemoglobin found in the oxygen-carrying blood cells when it combines with carbon monoxide. Carbon monoxide is a substance elaborated by combustion, and is found in nearly every fire situation. Carboxyhemoglobin forms when a person breathes in carbon monoxide and oxygen is replaced on the hemoglobin molecule by carbon monoxide. Normal carboxyhemoglobin levels are less than 5%, and in smokers this may reach as high as 10% though in most smokers it is in the 5-7% range. Very heavy smokers may have baseline levels slightly higher than 10%.
Carboxyhemoglobin medical expert witness specialties include forensic pathology, toxicology, internal medicine, pulmonology, pathology, occupational medicine, and reproductive toxicology.