Which of the following is NOT classified as a choking agent?

The classification of choking agents pertains specifically to substances that primarily cause damage to the respiratory system, leading to suffocation or difficulty breathing. Among the listed substances, mustard gas is not categorized as a choking agent. Instead, it is classified as a blistering agent or a chemical warfare agent that causes severe skin, eye, and respiratory tract injuries.

Chlorine, phosgene, and cyanide, on the other hand, are all recognized for their choking or asphyxiating properties. Chlorine and phosgene are particularly known for their effects on the lungs and ability to cause pulmonary edema, leading to respiratory failure. Cyanide, while primarily known as a systemic poison, can also interfere with oxygen utilization in the body and has choking-like effects in high concentrations.

Understanding the specific effects and classifications of these agents is crucial for hazmat response and safe handling procedures, especially in emergency situations involving chemical exposure. This distinction between blistering versus choking agents is significant in the training of hazardous material responders.