Propanethial-S-oxide is a gas
that's released when the cell wall
of an onion is broken. This gas reacts with the water in your eyes and produces sulphuric acid
. Getting acid in your eyes sucks, it also burns.
There are some ways to prevent this:
- Handle onions underwater
- Slice from the sides, rather than ends, avoid the root where the most gas is
- Wear goggles