So, I read about this on the internet four or five months ago (can't remember where).  I'm the type that can't chop 1/2 onion without having to stop because of the tears and pain, and I've tried many "solutions." But this works!  I have not had a single onion tear in many months and can chop as many onions as I like at one time.

Get a small desk fan. I bought mine at a garage sale for $3. I keep it in one of my cupboards just for this purpose. Aim the fan at your onion while chopping and away from your face, blowing all the fumes away.

Sorry if you have heard of this before, when I read it, it was new to me!