Carbon monoxide (CO) poisoning occurs when*1 pointCO molecules build up in the lungs, resulting in suffocationCO molecules replace the oxygen molecules carried by haemoglobin in the bloodCO causes disorientationCO affects the functioning of the brain, resulting in a feeling of euphoria

Carbon monoxide (CO) poisoning occurs when CO molecules replace the oxygen molecules carried by haemoglobin in the blood.

Here's a step-by-step explanation:

1. Carbon monoxide is inhaled and enters the lungs.
2. In the lungs, it is absorbed into the bloodstream.
3. Once in the bloodstream, carbon monoxide binds to haemoglobin, the molecule in red blood cells that carries oxygen to the body's tissues and organs.
4. The bond between carbon monoxide and haemoglobin is much stronger than the bond between oxygen and haemoglobin. This means that if both carbon monoxide and oxygen are present in the lungs, haemoglobin will preferentially bind with carbon monoxide.
5. As a result, the amount of oxygen that can be transported to the body's tissues and organs is reduced. This lack of oxygen can cause cells and tissues to die, leading to serious health problems including heart damage and death.
6. The symptoms of carbon monoxide poisoning - including headache, dizziness, weakness, nausea, vomiting, chest pain, and confusion - are actually symptoms of the body's tissues and organs not getting enough oxygen.