Carbon monoxide gas is more dangerous than carbon dioxide gas. Why?
Carbon dioxide (CO2) and carbon monoxide (CO) gases are emitted during the combustion of various fuels. Carbon monoxide is poisonous, whereas carbon-dioxide is non-toxic in nature.
Carbon monoxide is poisonous because it is capable of forming a complex with haemoglobin (carboxyhaemoglobin), which is more stable than the oxygen-haemoglobin complex. The concentration range of 3–4% of carboxyhaemoglobin decreases the oxygen-carrying capacity of blood. This results in headaches, weak eyesight, nervousness, and cardiovascular disorders. A more increased concentration may even lead to death.
Carbon dioxide is not poisonous. It proves harmful only at very high concentrations.