"How come onions make my eyes water?"

Good question. What happens is this: When you chop into the onion you release enzymes that form an invisible sulfur-based gas in the air. The moisture in your eyes reacts with the gas to create a very mild sulfuric acid.

Ouch!

Your eyes then form tears as a natural defense to try to dilute the acid and flush it out.

Now if you're like most people you'll try rubbing your eyes to relieve the sting but you're probably just making it worse. Your hands are likely coated with oils from the onion, which shift your tear ducts into overdrive.

What to do to prevent this? Try chilling the onion before you cut it. That might not completely work, but it should help.

You can also try cutting the onion underwater, though that could be a little difficult to manage.

If nothing works, try safety goggles. You might look a little silly, but at least you can see!