This happens regularly, once, every morning around the same time without fail, right before he goes to the bathroom for a while (not hard to guess why).
He makes no secret of it, lifts one leg, does what he feels he needs to do without any regard for people around him and continues like normal. Within 5 or so minutes he's gone.
The sound and the smell make me nauseous.
We're in an open plan office with "activity based desks" and he's been coming and sitting next to me for the last few weeks (he has no particular reason to sit here and has every right to choose where he sits - its first come first serve).
I don't want to move from my seating as I prefer it here.
Manager doesn't see any of this happen as he comes later in the day. None of the other workers are saying anything or outwardly acknowledging this behaviour.
What would be the professional way to deal with this behavior other than just accepting this as my life (or finding another job)
EDIT: This is not a duplicate of an office culture where there is a "chummy culture where people fart as a joke" this is a corporate office where I barely know this guys first name. This obviously makes what he is doing very out of place and awkward.