Phosgene

Phosgene is a chemical compound, with chemical formula COCl_{2.
It is composed of the elements Carbon (C), Oxygen (O), and Chlorine (Cl).}
Poisoning caused by phosgene depends on the amount of phosgene to which a person is exposed, the route of exposure, and the length of time that a person is exposed. Phosgene gas and liquid are irritants that can damage the skin, eyes, nose, throat, and lungs. Most people who recover after an exposure to phosgene make a complete recovery. However, chronic bronchitis and emphysema have been reported as a result of phosgene exposure. This colorless gas is a choking agent and has gained infamy for its use as a chemical weapon in WW1. 

Exposure to high levels of Phosgene may seriously harm and even kill wildlife. However, these effects are only likely when large amounts of Phosgene are released - for example, as a result of an accidental spill. Typical environmental levels are not sufficiently high to cause significant effects. It is not              considered likely that Phosgene pollution has any effects on the global environment. Human phosgene toxicity cases occur in too sporadic and sudden a fashion to allow randomized clinical trials. And so clearly, intentional exposure of human subjects to phosgene would be considered unethical.

Treatment for phosgene exposure consists of removing phosgene from the body as soon as possible and providing supportive medical care in a hospital setting. No antidote exists for phosgene. Exposed people should be observed for up to 48 hours, because it may take that long for symptoms to develop or reoccur.