Tear Gas - What It Is and How It Works

What Tear Gas Is and How Tear Gas Works

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By
Anne Marie Helmenstine, Ph.D.
Anne Marie Helmenstine, Ph.D.
Chemistry Expert
  • Ph.D., Biomedical Sciences, University of Tennessee at Knoxville
  • B.A., Physics and Mathematics, Hastings College
Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels.
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Updated on September 05, 2019

Tear gas, or lachrymatory agent, refers to any of a number of chemical compounds that cause tears and pain in the eyes and sometimes temporary blindness. Tear gas can be used for self-defense, but it is more commonly used as a riot control agent and as a chemical weapon.

How Tear Gas Works

Tear gas irritates the mucous membranes of the eyes, nose, mouth, and lungs. The irritation may be caused by a chemical reaction with the sulfhydryl group of enzymes, though other mechanisms also occur. The results of exposure are coughing, sneezing, and tearing. Tear gas generally is non-lethal, but some agents are toxic.

Examples of Tear Gas

Actually, tear gas agents aren't usually gases. Most compounds used as lachrymatory agents are solids at room temperature. They are suspended in solution and sprayed as aerosols or in grenades. There are different types of compounds that may be used as tear gas, but they often share the structural element Z=C-C-X, where Z denotes carbon or oxygen and X is bromide or chloride.

  • CS (chlorobenzylidenemalononitrile)
  • CR
  • CN (chloroacetophenone) which may be sold as Mace
  • bromoacetone
  • phenacyl bromide
  • xylyl bromide
  • pepper spray (derived from chili peppers and most commonly dissolved in a vegetable oil)

Pepper spray is a little different from the other types of tear gas. It is an inflammatory agent that causes inflammation and burning of the eyes, nose, and mouth. While it is more debilitating than a lachrymatory agent, it is harder to deliver, so it is used more for personal protection against a single individual or animal than for crowd control.

Sources

  • Feigenbaum, A. (2016). Tear Gas: From the Battlefields of WWI to the Streets of Today. New York and London: Verso. ISBN 978-1-784-78026-5.
  • Rothenberg, C.; Achanta, S.; Svendsen, E.R.; Jordt, S.E. (August 2016). "Tear gas: an epidemiological and mechanistic reassessment." Annals of the New York Academy of Sciences. 1378 (1): 96–107. doi:10.1111/nyas.13141
  • Schep, L.J.; Slaughter, R.J.; McBride, D.I. (June 2015). "Riot control agents: the tear gases CN, CS and OC-a medical review." Journal of the Royal Army Medical Corps. 161 (2): 94–9. doi:10.1136/jramc-2013-000165
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Helmenstine, Anne Marie, Ph.D. "Tear Gas - What It Is and How It Works." ThoughtCo, Feb. 16, 2021, thoughtco.com/tear-gas-what-it-is-and-how-it-works-604103. Helmenstine, Anne Marie, Ph.D. (2021, February 16). Tear Gas - What It Is and How It Works. Retrieved from https://www.thoughtco.com/tear-gas-what-it-is-and-how-it-works-604103 Helmenstine, Anne Marie, Ph.D. "Tear Gas - What It Is and How It Works." ThoughtCo. https://www.thoughtco.com/tear-gas-what-it-is-and-how-it-works-604103 (accessed March 23, 2023).
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