Why is inhalation exposure to carbon monoxide considered toxic?

Inhalation exposure to carbon monoxide (CO) is considered toxic primarily because carbon monoxide binds to hemoglobin in red blood cells much more effectively than oxygen does. This binding forms carboxyhemoglobin, which significantly reduces the amount of hemoglobin available to carry oxygen throughout the body. As a result, even if there is enough oxygen in the environment, the body is unable to utilize it effectively, leading to hypoxia at the tissue level. This is particularly critical since all cells, including vital organs, rely on oxygen for cellular respiration and energy production.

This mechanism of toxicity highlights the danger of carbon monoxide exposure, especially in enclosed spaces where CO can accumulate. The symptoms of carbon monoxide poisoning, such as headache, dizziness, confusion, and potentially loss of consciousness, directly stem from this impaired oxygen delivery and utilization.