Why do our eyes water when chopping onions? There is an interesting reason for this

Have you ever noticed your eyes watering and stinging while chopping onions in the kitchen? This is not due to the onion's pungent smell, but rather a chemical process that occurs involving the substances inside it.

When we cut an onion, its cells are damaged and sulfur-containing compounds react with enzymes. As a result, a volatile substance called syn-propanethial-S-oxide is released into the air. It reaches the surface of the eye and irritates the sensory nerves. The eye then begins to produce tears to wash away the irritant.

Interestingly, tearing up is not related to sadness or emotion — it is the body's natural defensive reaction.

How can you reduce eye watering when chopping onions?

• Chill the onion beforehand. Placing it in the refrigerator for 20–30 minutes before chopping can slow down the chemical reaction.

• Use a sharp knife. It damages fewer onion cells and helps reduce the amount of irritant released into the air.

• Ventilate the kitchen. Air circulation can reduce the substance from reaching your eyes.

So, tearing up while chopping onions is a normal occurrence. It is the body's way of protecting the eyes from irritants.