Which pollutant gas binds to hemoglobin much more strongly than oxygen?

CONCEPT

Gases that compete for hemoglobin are judged by their binding affinity to the heme group, not by ordinary solubility. A gas with much higher affinity forms a stable hemoglobin complex and reduces oxygen transport.

APPLICATION

Carbon monoxide is an air pollutant produced by incomplete combustion. It forms carboxyhemoglobin and has about 200-250 times the affinity of oxygen for hemoglobin, so the gas that fits the stem is carbon monoxide.

CONTRAST

• Carbon dioxide is mainly carried in blood through bicarbonate and carbamino forms; selecting it confuses normal carbon dioxide transport with pollutant-gas poisoning.

• Nitric oxide is associated with biological signaling and heme interactions; selecting it mixes that role with the common air-pollutant toxicity fact tested here.

• Hydrogen sulphide is toxic mainly through effects on cellular respiration enzymes; selecting it mixes a toxic-gas effect with a hemoglobin-transport fact.

RESULT

Carbon monoxide is the pollutant gas that binds hemoglobin much more strongly than oxygen.