Due to the nature of how COVID-19 is spread, many people have asked Royal Caribbean what the company does to protect passengers from the airborne spread of the virus.
Specifically, they want to know how the air will be circulated and filtered on board so that it is safe on their cruise ship.
In a blog, RCL said that its HVAC system continuously supplies 100% fresh, filtered air from outdoors to all indoor spaces.
The air is drawn from one side of the ship for cooling and ventilation, then removed via exhaust on the opposite side.
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.
In local spaces, such as smaller venues and staterooms, fan coil units provide an extra layer of protection, continuously scrubbing the air of pathogens, using a high-grade MERV 13 filter that captures aerosols 0.3 to 1 micron in size with 90% efficacy— fine enough to filter colds, flu germs, and coronavirus, the company claimed.
To prove the claim, RCL organised an independent assessment conducted by the University of Nebraska Medical Centre.
A bioaerosol assessment was undertaken on ‘Oasis of the Seas’.
This study involved releasing billions of 1µ aerosol-sized microspheres, each containing uniquely DNA bar coded inert virus surrogate, throughout the ship at certain pre-selected spaces (i.e. crew cabins, guest staterooms, and adjacent public spaces, including the casino, Studio-B & Disco/Lounge) to determine the efficiency and effectiveness of the vessel’s indoor air management strategies, as well as to understand the spread of the aerosols through the HVAC system and in between the adjacent private and public spaces.
The university’s medical centre study found that to clear the virus droplets from the air in about an hour, an HVAC system that changed the air in the room at least six times or more and used a filter with a MERV rating of 13, was needed.
A MERV rating of a filter refers to how much it can filter particles in the air, with a higher number meaning a higher level of filtration. The ratings range between 1 and 20. A rating of 13-16 is considered hospital level air quality.
This study confirmed that cross-contamination of air between adjacent public spaces is extremely low, and undetectable in most test cases, thanks to this system.
In addition to the study, as well as the new policies announced by the cruise line, the ‘Healthy Sail Panel’ came up with seven operations that RCL can undertake to manage indoor air and keep it clean.
- Enhance filtration– The Panel recommended that HVAC filters be upgraded to the highest level possible for each ship given the constraints of ship age and ventilation type (e.g. MERV 8 to MERV 13)
- Optimise airflow patterns– For example, the Panel recommended that cruise operators optimise airflow so that air is not recirculated; should air recirculation exist, given the HVAC system design, then the recirculated air must be filtered through a high-grade filter (i.e. MERV 13 or higher).
- Use negative pressurisation– The Panel recommended that cruise operators ensure that SARSCoV-2 isolation rooms are consistently at negative pressure. This means that cruise operators should ensure that there is sufficient negative pressure that will not be affected by doors opening and closing or people walking by. This should be optimised given the constraints of ship age and ventilation type.
- Minimise unfiltered, recirculated air– Cruise operators should provide air exhausted to the outside and maximise air changes per hour and filtration of air in staterooms, crew rooms, and public areas.
- Increase number of air changes per hour in certain areas– The Panel recommended that cruise operators pay special attention to areas where individuals would be most vulnerable to airborne transmission, and that they should prioritise increasing the number of air changes per hour in those areas. More specifically, isolation rooms in medical facilities on board should have six to12 air changes per hour, be at a negative pressure to the adjacent area, and have 100% air exhausted to the outside.
- Use portable HEPA filters (or other proven air cleaning systems) in congregate areas, as needed– Portable HEPA units have been shown to help reduce the level of airborne particles. This technology or other technologies that reduce the risk of airborne infection transmission may be used to augment other air management strategies.
- Maximise outdoor functions and physical distancing– The Panel recommended an overall emphasis on reducing indoor functions whenever possible, given that dilution is most achievable in outdoor settings. Further, cruise operators should ensure that guests understand that air management strategies do not negate the importance of following physical distancing protocols.
Many of the recommendations are incorporated in RCL’s robust system, the company claimed.
RCL added that it believed its air circulation plan makes the transmission of aerosol particles between spaces (such as those from a cough) “extremely low to virtually impossible.”
The company has also recently updated its health and safety standards.
This includes additional doctors and nurses on board each ship as well as onshore, plus new equipment.
On board medical centres include dedicated controlled care centres where potentially infectious guests or crew can be separated from non-coronavirus healthcare practices, the company said in another blog and posts on its website.
An infection control officer will be on board each ship who will monitor and co-ordinate the implementation of the company’s infection control plan.
Every on board physician will have received mandatory acute respiratory training before the trip.