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Why Does Slicing Onions Make Me Cry?

Onions
(Image credit: MaraZe/Shutterstock)

When your knife slices through a crisp onion, it tears through cells, releasing the cells’ contents.

Chemicals react to produce a sulfur-based gas. Once the gas contacts the water coating your eyes, it forms sulfuric acid, a fiery irritant. To rid your peepers of the intruder, your tear ducts work overtime.

If you aren’t game for sporting goggles in the kitchen, try moving your face farther away from the onion so the gas disperses before reaching your eyes.

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Michelle Bryner
Michelle writes about technology and chemistry for Live Science. She has a Bachelor of Science in Chemistry from the Salisbury University, a Bachelor of Chemical Engineering from the University of Delaware and a degree in Science Journalism from New York University. She is an active Muay Thai kickboxer at Five Points Academy and loves exploring NYC with friends.