Honestly - the air can be fairly dry due to constant air conditioning. I suggest taking some saline nose spray along to keep your sinuses well lubricated.
I think one of the reason people can get sick on cruise ships is because their sinuses dry out and that makes it easier for a germ to penetrate your sinusoidal membrane.
I am the editor, but I also speculate, ask questions and play devil's advocate. I reserve the right to change my mind.