What Is It?

Categorized as a blister agent, mustard gas refers to several manufactured chemicals -- many used in household products -- that don't occur naturally in the environment. Sulfur mustard is among them.

Mustard gas (search) is really a liquid and is not likely to change into a gas immediately if it is released at ordinary temperatures. As a pure liquid, it is colorless and odorless, but when mixed with other chemicals, it looks brown and has a garlic-like smell.

Mustard gas was used in chemical warfare and was made in large amounts during World Wars I and II. It was reportedly used in the Iran-Iraq war in 1984-1988. It's presently used in the United States for research purposes. The U.S. Secretary of Defense was instructed to destroy all remaining stocks of lethal military chemical agents, including mustard gas, by 1997.

Mustard gas has been a favorite chemical weapon in wars because it can be fairly easily delivered via conventional bombs, rockets and artillery shells and because mustard gas contamination can render an area unusable by enemy forces.

Experts say making mustard gas is easier than making nerve gases (search) but harder than weaponizing industrial chemicals such as chlorine. It would take vastly more mustard gas than nerve gas to kill the same number of people, limiting mustard gas' appeal to terrorists.

What Are the Symptoms of Exposure?

Mustard gas can burn skin, cause blisters and cause respiratory effects, such as coughing and bronchitis. Higher levels may cause death. It is also more harmful to the skin on hot, humid days, or in tropical climates. Mustard gas makes the eyes burn, eyelids swell and causes a person exposed to blink a lot. Skin exposure can cause second- to third-degree burns.

If one breathes mustard gas, it can cause coughing, bronchitis and long-term respiratory disease. If one is exposed to a large amount of mustard gas, victims can eventually die from it. Symptoms appear one to six hours after exposure. Mustard gas also attacks a cell's DNA (search), so it can cause cancer and birth defects.

How Is It Treated?

Although there's no specific antidote, symptoms are treated with antibiotics, painkillers, skin dressings and other therapies. Severely affected victims may need skin grafts, eye operations or treatment for chronic respiratory conditions such as emphysema. Decontaminating victims as soon as possible is vital so further exposure to others is kept at a minimum. This process includes rinsing exposed areas with water, removing any contaminated clothing and generously applying anti-burn skin ointments and talcum powder.

Who Has It/Where Can It Be Found?

Although there are no confirmed terrorist uses of mustard gas, there are unconfirmed reports that groups linked to Usama bin Laden's Al Qaeda network tried to obtain the ingredients to make mustard gas in Afghan labs.

Former Iraqi President Saddam Hussein used mustard gas on Kurds in northern Iraq during a 1987-88 campaign known as the Anfal. The worst attack occurred in March 1988 in the Kurdish village of Halabja: a combination of chemical agents including mustard gas, sarin and possibly VX killed 5,000 people and left 65,000 others facing severe skin and respiratory diseases, abnormal rates of cancer and birth defects, and a devastated environment. Experts say Saddam also launched about 280 small-scale chemical attacks against the Kurds. Iraq has maintained it has large stockpiles of mustard gas, sarin and tabun.