What makes carbon monoxide dangerous?

Each poison has a specific characteristic that makes it harmful. For carbon monoxide, the harmful trait involves the hemoglobin in the blood.

Hemoglobin consists of intricate proteins that are designed to bond with iron atoms. This structure allows oxygen to attach to the iron atom with minimal force. When blood passes through the lungs, the iron atoms in hemoglobin bind with oxygen. As the blood moves through areas of the body with lower oxygen levels, these iron atoms release the oxygen. The difference in oxygen pressure between the lungs and the body's oxygen-starved areas is very small. Hemoglobin is finely tuned to absorb and release oxygen precisely when needed.

Carbon monoxide binds tightly to the iron in hemoglobin, making it extremely difficult to release once attached. When you inhale carbon monoxide, it occupies all the oxygen-binding sites on your hemoglobin. As a result, your blood becomes incapable of carrying oxygen, leading to suffocation.

The strong bond between carbon monoxide and hemoglobin means that even low concentrations of carbon monoxide can be dangerous, especially with prolonged exposure. Levels as low as 20 or 30 parts per million (PPM) can be harmful if you're exposed for hours. A one-hour exposure to 2,000 PPM can lead to unconsciousness.

Common sources of carbon monoxide include cars, gas appliances, wood-burning stoves, and cigarettes.