Kids science questions no. 1.

Google this question and you’ll get lots of long answers describing complex chemical and neurological pathways involving enzymes, syn-propanethial-S-oxide and lachrymal glands. If you don’t have time to read all that – there’s a chemical in onions that gets into the air when the onion is cut and then it gets into your eyes. It irritates your eyes so they make tears to wash it away. However, that doesn’t really explain why the onion makes your eyes water, only how.