Excessive release of the pollutant carbon monoxide (CO) into the air may produce a condition in which oxygen supply in the human body decreases. What causes this condition?

1. When inhaled into the human body, CO is converted into CO₂
2. The inhaled CO has much higher affinity for haemoglobin as compared to oxygen
3. The inhaled CO destroys the chemical structure of haemoglobin
4. The inhaled CO adversely affects the respiratory centre in the brain

Explanation

Option (b) is correct

• Carbon monoxide binds with haemoglobin to form carboxyhaemoglobin, which reduces the oxygen-carrying capacity of blood. CO has about 200–250 times higher affinity for haemoglobin than oxygen, thereby displacing oxygen and causing tissue hypoxia.

Answer: (b) The inhaled CO has much higher affinity for haemoglobin as compared to oxygen