O2

[paulc20-]

What is 02

[hypercat54]

Oxygen. x

[simplesprout]

My telephone network provider ; )

[majji]

The O2 Arena is a multi-purpose indoor arena in the centre of The O2 entertainment complex on the Greenwich Peninsula in southeast London.

Sorry I just couldn't resist .....

[skischool]

Slightly higher than O1,it might help if you explained why you are asking the question?

Have fun with the answers but in medical lung jargon it normally refers to oxygen. x

[majji in reply to skischool]

Sirski - you obviously have a much kinder nature than I have - naughty me and my apologies to paulc20-