Which of the following is NOT a characteristic of a choking agent?

A choking agent, commonly recognized in the context of chemical warfare, is primarily characterized by its ability to cause damage to the respiratory system, leading to severe respiratory distress. This mechanism of action is fundamental because choking agents work by attacking the lungs and airways, inhibiting a person's ability to breathe effectively.

The correct choice identifies that a choking agent only affecting the skin on contact is not accurate. Choking agents, such as chlorine or phosgene, primarily affect the respiratory system rather than having significant effects through dermal exposure. While skin contact might lead to irritation in some cases, the critical impact of choking agents lies in their ability to incapacitate individuals by causing respiratory failure.

Additionally, choking agents can indeed be of chemical or biological origin, and they necessitate immediate medical attention due to the acute and potentially life-threatening effects they can produce. This underscores why the other characteristics listed are relevant and affirming of what defines choking agents in the context of CBRN response scenarios.