Carbon monoxide gas is more dangerous than carbon dioxide gas. Why?

The two gases that are emitted during the combustion of various fuels:

1. Carbon dioxide (CO₂) : Nox- toxic

2. Carbon monoxide (CO): Carbon monoxide is poisonous & toxic.

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. However, CO₂ is more tolerable in a human body because we are able to exhale it. And it doesn't have the same chemical properties that CO has. CO₂ doesn't react with the haemoglobin in our blood streams