Carbon monoxide is produced due to incomplete combustion, metallurgical operations and naturally by plants and animals. Normally, carbon monoxide has a brief residence in the atmosphere and gets oxidised to carbon dioxide. However, in congested and closed areas, it proves quite harmful. Carbon monoxide combines with haemoglobin and produces carboxyhaemoglobin. It impairs oxygen transport resulting in giddiness, headache, decreased vision, cardiovascular malfunction and asphyxia.