Which agent primarily causes effects through respiratory pathways?

The agent that primarily causes effects through respiratory pathways is identified as pulmonary agents. Pulmonary agents, such as chlorine and phosgene, are specifically designed to impact the respiratory system. When inhaled, these substances can damage lung tissue and lead to severe respiratory distress, making them particularly dangerous in situations where exposure occurs in enclosed or urban environments.

These agents act by causing irritation to the mucous membranes, leading to symptoms like coughing, choking, chest pain, and even more severe pulmonary injury or edema. Understanding the mechanism of action for pulmonary agents is crucial for medical personnel and first responders, as their immediate recognition and response can greatly affect patient outcomes following exposure.

In contrast, nerve agents primarily interfere with the nervous system by inhibiting the enzyme that breaks down neurotransmitters, leading to overstimulation of nerve endings, but they do not primarily function through respiratory pathways. Blister agents, such as mustard gas, mainly damage the skin and eyes, and their effects can also occur through ingestion or dermal contact rather than being primarily respiratory. Incendiary agents focus on causing combustion and destructive fires rather than acting directly on biological systems through inhalation or respiratory damage.