It's partial pressure not concentration. Air is toxic if you have 60 m of water above your head, but nowhere on earth do you have oxygen at 1.4 atm of partial p

It's partial pressure not concentration. Air is toxic if you have 60 m of water above your head, but nowhere on earth do you have oxygen at 1.4 atm of partial pressure. (Oxygen toxicity is really the one thing in recreational scuba diving training where they tell you "do this and you will positively die").