Yes you handicap.
O in it's self is ozone which is super toxic if you know anything about chemistry
Ozone is O
3, but yes, it is quite toxic.
Oxygen is a diatomic molecule, which means in almost all natural settings it'll covalently bond to itself to complete its second electron shell.
Breathing pure oxygen will not kill you.
Pure oxygen is not what we breathe. At sea level, the air we breath is 78% Nitrogen, 20.9% Oxygen, and the remaining 1.1% is made up of tiny percentages of gases like Argon, CO
2, Methane, Neon, Helium and Krypton. Oxygen is the only one we have use for though, all other molecules are simply cycled in and out of the lungs without bonding to the hemoglobin in our blood.
I hope that clears up all the misconceptions that were thrown around coupled with insults in this thread.