Which of the following air pollutants causes serious health issue due to its…

Answer: Carbon monoxide (CO) causes the most serious health issues by binding to hemoglobin with greater affinity than oxygen.

Key mechanism:

• Carbon monoxide binds to the ferrous iron (Fe2+) in hemoglobin to form carboxyhemoglobin.

• CO has roughly 200–250 times greater affinity for hemoglobin than oxygen, so it displaces oxygen and prevents oxygen binding.

• Formation of carboxyhemoglobin also shifts the oxygen–hemoglobin dissociation curve to the left, reducing oxygen release to tissues and producing tissue hypoxia.

Why the other gases are incorrect:

• Sulphur dioxide: an airway irritant that damages respiratory tissues but does not outcompete oxygen for binding to hemoglobin.

• Carbon dioxide: at very high concentrations causes asphyxia, but it is transported mainly as bicarbonate or bound at different sites on hemoglobin, not by displacing oxygen with higher affinity.

• Ozone: a powerful oxidant that injures the lungs and airways but does not form a high-affinity complex with hemoglobin.

Clinical relevance and management:

• Common sources of CO: incomplete combustion (vehicle exhaust, faulty heaters, indoor gas appliances).

• Symptoms: headache, dizziness, nausea, confusion, and in severe cases loss of consciousness due to tissue hypoxia.

• Treatment: remove from exposure, give 100% oxygen; hyperbaric oxygen is considered for severe poisoning.