If you have been on an airplane before, you know that the flight attendant will always tell you to put your mask on if the cabin loses pressure.
However, they constantly tell you to do it first before helping others. But why? Surely you should help children first?
A US engineer and aspiring astronaut has created a video to show the exact science behind this rule.
Destin Sandlin, who "explores the world using science", entered a special chamber with an astronaut to find out what happens if you don't put on your mask.
After a few minutes, Sandlin starts to lose brain function and cannot identify basic shapes. Soon, he can't even speak or put his mask on and someone must step in and put it on for him to prevent him dying.
So always put your own mask on first before helping others because, by the time you've helped everyone else, you may not know how to help yourself.