Exposure to car exhaust in a closed garage is most consistent with which poisoning?

• A. Anemia
• B. Hydrogen Sulfide Poisoning
• C. Carbon Dioxide Toxicity
• D. CO Poisoning

Answer: (D)

Carbon monoxide poisoning is the best match when someone is exposed to car exhaust in a closed space. Car exhaust contains CO, a colorless, odorless gas that can accumulate quickly in an enclosed area. CO binds to hemoglobin with a much higher affinity than oxygen, forming carboxyhemoglobin, which prevents oxygen from binding and shifts the remaining hemoglobin's ability to release oxygen to tissues. This leads to tissue hypoxia and the symptoms you’d see with CO exposure—headache, dizziness, confusion, nausea, and fainting—often before someone even notices something is wrong. The situation described is not best explained by anemia, which is a chronic, not acutely life-threatening, reduction in red blood cells or hemoglobin; hydrogen sulfide poisoning has a characteristic rotten-egg odor and different clinical clues; and carbon dioxide toxicity requires very high CO2 levels and presents with hypercapnia and acidosis, not the classic CO-deprivation pattern from car exhaust. Management focuses on moving the person to fresh air and delivering 100% oxygen promptly to displace CO, with hyperbaric oxygen considered in severe cases.