Multiple choice CO is a harmful pollutant because it has more affinity for haemoglobin reacts quickly with UV radiations has less affinity for Hb cannot complete with oxygen Reveal answer Fill a bubble to check yourself A Correct answer Explanation CO has about 200-250 times higher affinity for hemoglobin than oxygen, forming carboxyhemoglobin. This displaces oxygen and reduces oxygen delivery to tissues, causing hypoxia even when sufficient oxygen is present in the air.