Yes, smoking optional rooms are only on the 4th floor. Not the whole 4th floor, but they are only on the 4th floor. I would probably avoid the 4th floor if possible if your allergy is servere. The rooms are in the first hallway of the 4th floor and I could smell the smoke well in the hallway. If worse comes to worse and you have to take a 4th floor non-smoking room there is a way to avoid that first hallway. I would walk on the first floor down to the 2nd elevator and then I would go up to the fourth floor, this would avoid the smoking rooms all together.