Dera!ler?

I do not know if what the man said at the beginning of the video is correct or not. From what found after watching him it appears Phosgene gas and Mustard gas are 2 different things. I am trying to learn what is really going on just like everyone else.

Science History Institute
A brief history of chemical war

Chlorine gas, used on the infamous day of April 22, 1915, produces a greenish-yellow cloud that smells of bleach and immediately irritates the eyes, nose, lungs, and throat of those exposed to it. At high enough doses it kills by asphyxiation.

Phosgene, which smells like moldy hay, is also an irritant but six times more deadly than chlorine gas. Phosgene is also a much stealthier weapon: it’s colorless, and soldiers did not at first know they had received a fatal dose. After a day or two, victims’ lungs would fill with fluid, and they would slowly suffocate in an agonizing death. Although the Germans were the first to use phosgene on the battlefield, it became the primary chemical weapon of the Allies. Phosgene was responsible for 85% of chemical-weapons fatalities during World War I.

Mustard gas, a potent blistering agent, was dubbed King of the Battle Gases. Like phosgene, its effects are not immediate. It has a potent smell; some say it reeks of garlic, gasoline, rubber, or dead horses. Hours after exposure a victim’s eyes become bloodshot, begin to water, and become increasingly painful, with some victims suffering temporary blindness. Worse, skin begins to blister, particularly in moist areas, such as the armpits and genitals. As the blisters pop, they often become infected. Mustard gas could also contaminate land where it had been deployed. Exposure sensitized victims; further exposure even at lower doses produced symptoms. Mustard gas caused the highest number of casualties from chemical weapons—upward of 120,000 by some estimates—but it caused few direct deaths because the open air of the battlefield kept concentrations below the lethal threshold.