I share an office with someone who smells extremely bad, maybe the worst I have ever known anyone to smell in my life (I'm not exaggerating, it smells like they have some item of clothing which has not been washed for years). Breathing it in you can almost feel the hairs in your nose being singed it is so corrosive.
I normally would not care about someone's smell as I don't get that close to people, but this guy's smell permeates everything in a radius of a five metres around him and even walking through a corridor where he has been is unpleasant. Opening all the windows in the office space does not help.
What is the best way to approach him about this without upsetting him or offending him?
I work at a university as a research student, so I don't really have a manager to go to, there is no-one who manages that office space and not a HR department as far as I know.