Fun article on onions and why they burn your eyes.
Did not know the smell is not what causes the irritation.
You can chill the onion in the freezer for a couple of minutes. Onions in the frig sometimes makes everything smell like onions which also makes it taste like onions. Also when you cut them move the cutting board away from your body so the fumes don't raise right into your eyes.
I have found refrigerating the onion stops the tearing. The coldness keeps the chemicals from spreading.
Technical ifyou don't have a scientific mind.