For patients with carbon monoxide poisoning, the hemoglobin in their blood decreases progressively, while carboxyhemoglobin increases in varying degrees and magnitudes, because the concentration and positivity of carboxyhemoglobin can reflect the level of poisoning in patients with carbon monoxide poisoning. In mild poisoning, the concentration of carboxyhemoglobin in the blood is 10%-30%, and for moderate poisoning, the concentration of carboxyhemoglobin in the blood reaches 30%-40%. In severe carbon monoxide poisoning, the concentration of carboxyhemoglobin can be as high as 50% or even more. This is because carbon monoxide and hemoglobin bind, and the binding force is 240 times greater than that of oxygen. Therefore, once the carboxyhemoglobin increases and is accompanied by the typical symptoms of carbon monoxide poisoning, you must immediately go to the hospital for hyperbaric oxygen chamber treatment.