CO has a much greater affinity for Hb than oxygen. Using your knowledge and the data presented in the graph, why is CO poisoning so dangerous?
CO binds Hb at much lower partial pressures, and binding is mostly irreversible. So, a small amount of CO will bind a lot of Hb, and will prevent Oxygen binding, decreasing Oxygen carrying capacity and availability for exchange. With prolonged exposure, oxygen carrying/saturation quickly falls to zero, and the person dies.