I stumbled upon this amazing image the other day.
CHEMICAL WARFARE IN THE TWENTIETH CENTURY© IWM (D 648)
Here we see a nurse at the Great Ormond Street Children's Hospital in London in 1940 fitting a baby with a gas mask during a Chemical Warfare drill. Note the bellows arrangement on the side.
Despite many lectures frightening the public about the dangers of phosgene and mustard gas, those threats never materialised during World War II.
Enough damage was done with plain old bullets, shrapnel and infection.