phosgene

Common name for carbonyl chloride, used as a chemical weapon in World War I. It is not immediately irritating when inhaled but causes an acute inflammation of the lungs; victims frequently felt quite well after a short rest but then died suddenly a few days later.

First used by the Germans in a cloud attack December 1915, it was rapidly adopted by the other combatants and became the principal battle gas of the Allies. More than 80% of the gas casualties of the war were caused by phosgene.