Poison Gas is a term for various lethal or temporarily disabling gaseous substances used in riot and warfare. The term chemical warfare includes the use of poison gases, as well as incendiary materials and smoke producing devices. Gas masks and heavy, gas proof clothing protect adequately against most poisonous gases.

Types of Gases Used against Humans:

• Blister Gases like mustard gas was first used by the German Army in WWI, it was the most lethal of all the poisonous chemicals used during the war and it was almost odorless and took twelve hours to take effect. Mustard gas often remains on the ground for several days. This gas produces a reddening of the eyes, skin, and mucous membranes, followed by blisters. The bronchial tubes are irritated, and pneumonia usually develops. Mustard gas, which is lethal only in heavy concentrations, is used to incapacitate troops.
• Choking Gases like chlorine, phosgene, and diphosgene, attack the respiratory tract. Chlorine was first used in WWI, it destroy the respiratory of its victims (it produces quick irritation and choking) and this led to a slow death by asphyxiation. The immediate effect of phosgene and diphosgene is less noticeable, but the lungs slowly fill with fluids and the victim suffocates within a few days.
• Nerve Gases, such as Tabun (or GA), Sarin (or GB), and Soman (or GD), are colorless, odorless, and tasteless. These gases destroy the normal functioning of nerves and muscles. It can be easily absorbed through the skin by means of inhalation, or ingestion. The victim dies within a few minutes after the poisons enter the blood.

Symptoms includes: Runny nose, Bronchial secretions, Tightness in the chest, Blurring of vision, Pin-Point Pupils, Drooling, Excessive perspiration, Nausea, Vomiting, involuntary defecation, urination, muscle tremors, convulsions, Coma, Death

• Psychochemical Gases like BZ are incapacitating agents that attack the brain, which causes hallucinations or even delirium and short memory loss. Its effect may be appear half an hour after exposure and may persist for some days.
• Vomiting Gases, DM (diphenylaminochloroarsine) appears as light yellow to green crystals. This gas rarely kill, but cause severe sneezing, coughing, headache, nausea, and vomiting. DM, also called adamsite, was developed as riot control agents and as emesis-inducing agents to promote removal of personal protective gear during chemical warfare.
• Tear Gases like CN (chloroacetophenone) and CS (ochlorobenzalmalononitrile) are substances which in low concentrations produce severe eye irritation, resulting in a blinding flow of tears. Other than the eyes, most tear gases can cause irritation in the nose, mouth, throat and sometimes also in the skin, particularly in the moist and warm parts. Tear gases are used principally by police troops for mob control.

Methods Used in Delivering Gas Attack:

• In the gas cloud or mist, the wind is used to carry the gas to the enemy lines.
• Gas can also be delivered in artillery shells and aerial bombs.
• Sprayed from low-flying aircraft.