Why do onions hurt your eyes?!
Answers: It's the acids and enzymes, especially the sulfides, that cause that. When exposed to air they form a gas that irritate the nerve endings in the conjunctiva. Chop faster.
It is in the oils that are in them.
Cutting Onions.
Use a very sharp knife, and slice, don't chop, or just push your knife down through them.
You could put them in the fridge for an hour.
Running under cold water will take some of the sharpness away, and it is an ideal way to tone them down if you wish to use them uncooked in a salad.