Why do onions make our eyes water?
Our eyes are really watering all the time. Tears come from special tear glands in the corners of our eyes. When we blink, our eyelids squeeze little drops of tears from the glands to bathe our eyes, to keep them from drying out and to help wash away specks of dirt.
Onions give off a strong oil when they are peeled or cut.
This oil quickly forms a vapor which gives the onion its sharp taste and odor, and also irritates the eyes.
The eyes react by blinking and by producing a flow of tears to wash away the irritating vapor.
The onion is not a root but a bulb with overlapping, fleshy leaves.
Red onions are usually the strongest in flavor. Spanish and Bermuda onions are milder in flavor, the kind we like to eat raw.
Cooking onions drives off some of their oil and removes most of their strong flavor. – Dick Rogers