1. Overview: Carbon monoxide is a colorless, odorless, non-irritating gas. Carbon monoxide poisoning is mostly caused by gas pipeline leakage, gas switch failure and operating errors, and the lack of ventilation equipment in the room, or the use of gas water heaters for bathing, ammonia synthesis, coking, steel smelting and household coal stoves for heating, poor ventilation or improper protection. After inhalation of carbon monoxide, it enters the blood circulation through the alveoli and mainly forms carboxyhemoglobin (HbCO) with hemoglobin. Because the affinity of CO to Hb is 240 times greater than that of O2 to Hb, the oxygen carrying capacity of the blood is reduced; and once HbCO is formed, its dissociation is slower than that of oxyhemoglobin (HbO2) (only 1/3600), and the presence of HbCO also affects the dissociation of HbO2, hindering the release and transfer of oxygen, leading to hypoxemia, causing tissue hypoxia, and severe cases cause death.