Circulating red blood cells

In our circulation, red blood cells are designed to carry oxygen and can carry carbon dioxide and carbon monoxide as well.

Red blood cells pick up oxygen in our lungs and deliver it to our cells throughout our body. As the oxygen reaches the cells, an exchange takes place: Oxygen leaves the red blood cell and enters the tissue cell and carbon dioxide that has been produced inside the tissue cells travel back to the lungs where it is released out into the air. This exchange happens with every breath we take.

When there is increased levels of carbon monoxide present in the air we breathe, it is toxic to us. It enters the lungs where it is picked up by red blood cells.

There are no clues when carbon monoxide is present: carbon monoxide is colorless, odorless, tasteless and does not make us cough or sneeze. 

Carbon monoxide poisoning causes headache, nausea, vomiting, dizziness, fatigue, and a feeling of weakness. These symptoms are classically associated with many other conditions like the flu, food poisoning and hangovers and so the unsuspecting person does not recognize they are in mortal danger. As more and more carbon monoxide is breathed in, the symptoms worsen and when approximately one half of the red blood cells are saturated with this odorless, colourless and tasteless gas, it can cause seizure, coma and death.