Just another PSA because I have seen people saying this a few times in the last few days
Blood is never blue ...it does not "hit oxygen" and turn red. This is a myth and really anyone who has ever had a blood test should realize this.
/Rant oh and ps this is talking about healthy people. I dont know if there is any far off medical thing that can turn blood blue. But if that is real it is rare and I am not talking about that.