Why is carbon monoxide (CO) considered a dangerous pollutant?

Carbon monoxide (CO) is classified as a dangerous pollutant primarily due to its ability to bind with hemoglobin in the blood. When carbon monoxide enters the bloodstream, it attaches to hemoglobin more effectively than oxygen, creating carboxyhemoglobin. This significantly reduces the blood's capacity to transport oxygen throughout the body, leading to a risk of tissue hypoxia, which can be life-threatening. The implications of reduced oxygen delivery are profound, potentially causing symptoms such as headaches, dizziness, confusion, and in severe cases, loss of consciousness or death.

Other pollutants mentioned do not share this direct mechanism of affecting oxygen transport. For instance, while carbon monoxide does not cause skin irritation, create ground-level ozone, or contribute significantly to the greenhouse effect like CO2, its specific interaction with hemoglobin is what makes it particularly hazardous to human health.