On Royal Caribbean ships, 100% fresh ocean air is continuously supplied from outside. Intake of air occurs on one side of the ship for cooling and ventilation, then the air is removed via exhaust on the opposite side of the ship. This continual intake of fresh air replaces the air in any space, with a total air change up to 12 times an hour in staterooms, and about 15 changes an hour in large public spaces. Fan coil units in your stateroom and public spaces provide an extra layer of protection, continuously scrubbing the air of pathogens, using a high-grade MERV 13 filter that captures aerosols 1 to 3 microns in size with 90% efficacy — fine enough to filter cold and flu germs and coronavirus. An independent study by the University of Nebraska Medical Center and the National Strategic Research Institute onboard Oasis of the Seas confirmed that cross-contamination of air between adjacent spaces is virtually impossible thanks to this powerful system.