CHEMICAL HAZARD - What Is Mustard Gas?

By Elizabeth Palermo, LiveScience Contributor

Mustard gas was used to lethal effect during World War I, and early gas masks offered little protection. Credit: Susan Law Cain | Shutterstock.com View full size image

Mustard gas, or sulfur mustard (Cl-CH₂CH₂)₂S, is a chemical agent that causes severe burning of the skin, eyes and respiratory tract. It can be absorbed into the body through inhalation, ingestion or by coming into contact with the skin or eyes.

First used during World War I, the gas is effective at incapacitating its victims en masse. Sulfur mustard is generally colorless in its gaseous state, though it may have a faint yellow or green tint. It's most easily recognized by its trademark "mustardy" odor, though some compare its smell to that of garlic, horseradish or sulfur.

The gas is a vesicant, or blister-agent, causing redness and itching of the skin that results in yellow, pus-filled blisters. Because mustard gas strips away the mucous membranes of the eyes, nose and respiratory tract, victims may also experience irritation of the eyes, temporary blindness, runny nose, cough, shortness of breath and sinus pain. The digestive tract is also affected, resulting in abdominal pain, diarrhea, fever and vomiting.