What is a significant health risk associated with exposure to carbon monoxide?

Exposure to carbon monoxide (CO) poses a serious health risk primarily due to its ability to inhibit oxygen transport in the blood. When inhaled, carbon monoxide binds to hemoglobin in red blood cells much more effectively than oxygen does, forming carboxyhemoglobin. This binding prevents hemoglobin from carrying oxygen to the tissues and organs, leading to oxygen deprivation in vital areas of the body.

As a result, people exposed to elevated levels of carbon monoxide may experience symptoms such as headache, dizziness, confusion, and in severe cases, loss of consciousness or even death due to asphyxiation. This disruption in oxygen transport can severely impact bodily functions, particularly in the heart and brain, where adequate oxygen levels are critical for sustaining life and health.

The other options do not present valid health implications of carbon monoxide exposure. There is no evidence to support that CO leads to improvement in cognitive or respiratory functions or that it causes a reduction in heart rate; rather, exposure increases the risk of cardiovascular problems due to the strain caused by hypoxia (lack of oxygen).