Concerns about air quality above a cruise ship is kind of silly when you realize that the ship is always moving. When it gets into a port, everybody gets off the ship to do things ashore.
Those cruise ships are about the cleanest environments as they have hundreds of crew members who are constantly scrubbing things down and keeping everything shiny clean. As soon as you leave your cabin, somebody is in there cleaning it and refreshing the fruit in your fruit bowl, etc.
The think I like best about the cruise ships is that you literally don't have to lift a finger to do anything that resembles work of any kind. In the staging area just before the cruise, your luggage is taken away to your cabin. You get up from your pool chair for even a few minutes and you will find your towel replaced with a fresh one. When you finish your drink, the empty glass magically disappears. Way less stressful then a trip to say Disneyland, where you are constantly trying to arrange transportation here and there and making reservations at restaurants and so forth. On a ship, all of that is done for you and you have your own assigned seating at the dining room. And if you don't show up, you get a voicemail in your cabin offering to bring the meal directly to you.
It's hard to describe to anybody who hasn't had the experience but once you have your first cruise, you are basically hooked for life.
It’s easier for the crew to clean up the smaller windowless room after you’ve blown your wine, sushi, and Bananas Foster all over the walls and ceiling.