Choking agents (lung-damaging agents)
Choking agents are known to cause pulmonary edema, which is the accumulation of fluid in the lungs. Examples of lung-damaging agents include phosgene (CG), diphosgene (DP), chloride, and chloropicrin (PS). Phosgene is the best known of the choking agents. It is produced by heating carbon tetrachloride, which was once used as a fire-extinguishing agent. It was discontinued as a fire-extinguishing agent because when it came in contact with hot surfaces, it released phosgene gas. Choking agents irritate the bronchi, trachea, larynx, pharynx, and nose, which may result in pulmonary edema and contribute to a choking sensation.