Carbon monoxide has affinity for haemoglobin, 200 times more than oxygen. If a person inhales carbon monoxide for 6 to 8 hours, then carbon monoxide has poisonous effect. Carbon monoxide binds with haemoglobin and forms carboxyhaemoglobin, which can not absorb oxygen. Thus, red blood corpuscles lose the capacity of carrying oxygen to various parts of the body. As a result of which, the person dies for want of oxygen.