Why is carbon monoxide poisonous?
Carbon monoxide (CO) is a poisonous, colourless, odourless and tasteless gas, which is formed when there is not enough oxygen present when carbon-based fuels such as wood and oil are burnt (ie incomplete combustion). Exposure to carbon monoxide can cause symptoms that include headaches, nausea and even death.
Carbon monoxide poisoning is mainly caused by your body’s cells being deprived of oxygen, which is used to release energy from your food via aerobic respiration. Oxygen is usually carried through the circulatory system by haemoglobin found within red blood cells, with each haemoglobin protein being able to carry up to four oxygen molecules at a time. However, carbon monoxide reduces the amount of oxygen being delivered to cells in two ways. Firstly, the affi nity (strength and likelihood of binding) of haemoglobin to carbon monoxide is over 200 times greater compared to that with oxygen. This means carbon monoxide is more successful while competing for the same binding site as oxygen on haemoglobin, therefore reducing the amount of oxygen that’s carried. Secondly, if a carbon monoxide molecule binds with haemoglobin, subsequent oxygen molecules are bound more tightly, preventing the oxygen from being released.