What type of agent do phosgene (CG) and chlorine (CL) represent?

Phosgene (CG) and chlorine (CL) are classified as choking agents due to their effect on the respiratory system. Choking agents interfere with normal breathing by causing irritation and damage to the lungs, often leading to pulmonary edema. This is a key characteristic that defines choking agents, which primarily target the respiratory tract and can create a sensation of choking or asphyxiation in individuals exposed to them.

Both substances produce acute health effects that can manifest rapidly on exposure, underscoring their classification as agents that can cause immediate distress and potentially fatal outcomes if sufficient concentrations are inhaled. Choking agents are utilized in scenarios to incapacitate or harm individuals by significantly damaging lung tissue and restricting the ability to breathe. This is why phosgene and chlorine fit squarely within this category.

The other classifications—blood agents and biological agents—do not accurately describe the primary mode of action or effects of phosgene and chlorine. Blood agents affect the blood's ability to transport oxygen, while biological agents are living organisms or derivatives that can cause disease in living hosts. Neither of these classifications pertains to the specific mechanical function of choking agents, further solidifying the classification of phosgene and chlorine as choking agents.