Question

Which of the following air pollutants reduces the oxygen-carrying capacity of blood?

• A. Carbon dioxide
• B. Carbon monoxide
• C. Sulphur dioxide
• D. Nitrous oxide

Answer 1

The correct option is B

Carbon monoxide

Carbon monoxide can bind to haemoglobin and does so 240 times more tightly than oxygen, forming a compound called carboxyhaemoglobin. This means that if carbon monoxide and oxygen are inhaled, carbon monoxide will preferentially bind to haemoglobin. This reduces the amount of haemoglobin available to bind with oxygen, so the body and tissues become starved of oxygen. Carbon monoxide is colourless and odourless so it is difficult to detect. Because of its ability to form carboxyhaemoglobin, it is toxic.