Hemoglobin that carbon monoxide instead of the regular air bound to it. Carbon monoxide has actually a much stronger binding to hemoglobin than oxygen. Carboxyhemoglobin is formed in carbon monoxide poisoning and causes oxygen deficiency in the human body. The source regarding the carbon monoxide can be exhaust (particularly from a car or truck, truck, vessel, or generator), smoke from a fire, or cigarette smoke. The amount of carboxyhemoglobin is a measure of the degree of carbon monoxide visibility.