Which substance would be classified as a chemical asphyxiant?

Which substance would be classified as a chemical asphyxiant?

• A. Carbon dioxide
• B. Nitrogen
• C. Hydrogen cyanide
• D. Methane

Answer: (C)

Chemical asphyxiants work by preventing the body's cells from using oxygen, not just by reducing the amount of oxygen in the surrounding air. Hydrogen cyanide fits this, because it blocks cellular respiration at the mitochondrial level (inhibiting cytochrome oxidase). Even with plenty of oxygen present, the cells can’t extract or use it, leading to rapid hypoxia and potentially fatal outcomes. The other substances here primarily reduce the oxygen available in the environment (simple asphyxiants) or are inert and not toxic in the same way; they don’t interfere with cellular oxygen use. So hydrogen cyanide is the substance that acts as a chemical asphyxiant.

Chemical asphyxiants work by preventing the body's cells from using oxygen, not just by reducing the amount of oxygen in the surrounding air. Hydrogen cyanide fits this, because it blocks cellular respiration at the mitochondrial level (inhibiting cytochrome oxidase). Even with plenty of oxygen present, the cells can’t extract or use it, leading to rapid hypoxia and potentially fatal outcomes. The other substances here primarily reduce the oxygen available in the environment (simple asphyxiants) or are inert and not toxic in the same way; they don’t interfere with cellular oxygen use. So hydrogen cyanide is the substance that acts as a chemical asphyxiant.