Phosgene is a colourless gas with a slightly acrid smell reminiscent of rotting hay, three times heavier than air, which breaks down into hydrochloric acid and carbonic acid when brought into contact with water. As little as 2-5 cubic centimeters in a cubic meter of air can be lethal in cases of prolonged exposure; 5-10 cubic centimeters lead to severe irritation of the eyes and the respiratory organs; 20-25 cubic centimeters cause intense pneumonia within minutes. Dosages over 50 cubic centimeters are lethal.

Mustard gas has a faint, mustardy smell and can remain active in the
open air for days, even weeks during winter. Symptoms only appear once it is too late for help. The skin erupts in red spots, which develop
into blisters. The lungs are completely destroyed by an inhalation of
12 milligrammes per minute. As opposed to phosgene victims, who gasp
for air, mustard gas patients are brooding, numb and indifferent. The
eyes are damaged by the gas, leading to suppuration and destruction of the conjunctiva, cornea, and the whole eye. As research has shown,
mustard gas penetrates uniforms and waterproof cloth within 30 minutes; rubber is far less permeable.

Chlorine was used as a combat gas in the Great War. A chlorine
concentration of 1:20000 will disable soldiers from continuing to
fight; a concentration of 1:10000 leads to asphyxiation, cyanosis, and is ultimately lethal. Death is usually immediate, but will occasionally follow after a fatal bought of bronchopneumonia. Chloric gas irritates the mucous membranes and causes weeping, a runny nose, coughing, thorax pains, and asphyxiation. The discoloration of the face resembles that caused by phosgene poisoning.