Carbon monoxide (CO) is highly poisonous in nature. Air containing even less than 1% of carbon monoxide can be fatal, if breath it for about 10 to 15 minutes. It combines with Haemoglobin in the blood and form carboxy haemoglobin, which reduces the oxygen carrying capacity of blood. The oxy-haemoglobin carries oxygen to various body parts but when carbon monoxide is combined, it stops the normal circulation of oxygen and may cause death due to suffocation.