What makes carbon monoxide particularly dangerous even at low levels?

Carbon monoxide is particularly dangerous at low levels because it binds to haemoglobin in the blood more effectively than oxygen does. Hemoglobin is a protein in red blood cells responsible for transporting oxygen from the lungs to various tissues in the body. When carbon monoxide is inhaled, it competes with oxygen for binding sites on hemoglobin, forming carboxyhemoglobin. This reduces the amount of oxygen that can be carried in the bloodstream, leading to tissue hypoxia, which is a lack of oxygen essential for cellular function. Even small amounts of carbon monoxide can significantly affect the body's ability to transport oxygen, resulting in potentially severe health issues such as headaches, dizziness, confusion, and can ultimately lead to unconsciousness or death if exposure continues.

In contrast, while lung inflammation, contribution to greenhouse gas effects, and the presence of a sweet odor may be relevant in other contexts, these factors do not account for the immediate and life-threatening effects that carbon monoxide has on the oxygen transport system in the body.