Last updated: November 23, 2021
As we start to spend more time indoors over winter once more, there will again be concern over whether the air we breathe while inside plays a part in the spread of Covid. RightRooms looks at the science behind ventilation and the spread of Covid, and how hotels have been addressing this concern.
Routes of transmission
Covid is primarily transmitted via invisible droplets that are generated when an infected person coughs, sneezes laughs, talks or breathes near to someone else. While scientists are still learning about Covid and routes of transmission, one study found that droplets generated when an infected person talks can remain suspended in the air for up to 14 minutes. The researchers concluded that there is a ‘substantial possibility’ of airborne virus transmission in confined spaces. This has lead The Scientific Advisory Group for Emergencies to emphasise that “Ventilation should be integral to the Covid-19 risk mitigation strategy for all multi-occupant public buildings”.
Fresh air is key
The guiding principle behind ensuring a fresh air supply in a hotel is that contaminated air will be replaced by clean air from outside. A natural method is to open the window. A recent review of HVAC guidelines recommends that hotels open windows for about 15 minutes before occupation of a room, especially if it was occupied beforehand.
Opening windows may not be possible in hotels where windows are sealed or the weather conditions mean it is not practical to do so.
Industry regulator Refcom refutes the idea that ventilation systems are part of the problem, claiming they are in fact part of the solution. Most hotels will have a central ventilation system designed to extract stale air from the rooms and pipe it to an air handling unit, which is located on the roof. Fresh air is then pulled in from outside and sent back into the building.
A study in The Journal of Fluid Mechanics explains that ventilation systems work in two main ‘modes’. ‘Mixing Ventilation’ is the most common; whereby vents are placed to keep the concentration of air in the space constant and uniform; virus particles are dispersed evenly throughout the space.
‘Displacement’ Ventilation works by placing vents at the bottom and top of a room; creating a cooler lower zone and warmer upper zone. Warm air is extracted through the top part of the room. Given that exhaled breath is warm, it rises, therefore being extracted by the ventilation system rather than breathed in by someone else. The study suggests that displacement ventilation could reduce the risk of cross-contamination of breath, thereby decreasing risk of exposure to Covid.
Refcom recommends that hotels should endeavour to turn off the recirculation function where possible and prioritise a fresh air supply. While this uses significant energy, ‘Health is more important than energy efficiency right now,’ says Graeme Fox, Head of Refcom.
According to Premier Inn, air is not mixed or recirculated in its hotels. Each room acts as an individual isolated space with its own source of supplementary fresh air.
Most rooms are likely to have a wall-mounted air conditioning system. RightRooms spoke to Air Conditioning Specialists, Airtech who say that hotels should be doing the following:
- Regularly cleaning the filters in their AC systems with industry-approved sanitisers (which help to remove particles from the air)
- Ensuring adequate replacement of filters
- Adhering to a schedule of maintenance of the system every six to eight weeks
- Keeping the system running for longer hours
- Running the system at maximum outside airflow for two hours before and after spaces are occupied.
Airtech confirms that the specific percentage of fresh air entering a room very much depends on the system and its programmed settings. These settings will automatically change in order to maintain optimal conditions in a room.
Facilities managers may want to reduce the amount of fresh air bought in during winter when trying to heat the building. However, whether the AC is set to heating or cooling mode doesn’t make a significant difference. Some organisations, such as Airtech, are trialling a new technology called Blue Science UV, which is a UV light strip inside the AC machine that kills bacteria as air enters the filter.
The UK Health and Safety Executive recommends the use of ceiling fans to improve the circulation of outside air and prevent pockets of stagnant air. However, this is only recommended provided there is good ventilation in the room, to prevent re-circulation of potentially contaminated air. The CDC recommends ceiling fans that allow for upward airflow rotation, a sentiment echoed by experts at the Yale School of Public Health who suggest switching off sensor-based ventilation, opening windows and reversing ceiling fan blades to take air away from occupants.
The World Health Organization says table fans are safe in single-occupancy rooms but they should be avoided in spaces where several people are present and hotels should minimise air blowing from one person directly to another.
With this in mind, these are some questions you can ask when booking your hotel stay:
- Is there a window that you can open in your room?
- Does the hotel have clear guidelines on its website in relation to Covid-19 measures?
- Are there windows or ceiling fans in the restaurant or bar?
- If there is air-con or heating, are they using HEPA filters and cleaning them regularly?
- Is there an extraction fan in the toilet in your room, and in the rest of the hotel?
Do the staff open the windows in the rooms when they clean them between guests?
How to manage less-than-ideal ventilation
If you believe your hotel has less-than-ideal circumstances for ventilation, there are several things you can do:
Request to change rooms to one that has better ventilation
Wear your mask whenever you leave your room and keep it on throughout the hotel
Bring your own portable air filtration system that uses HEPA filters to plug in in your room.
Although it can be hard to find reference to ventilation in hotel guidances, as long as they are following government guidelines, they will be thinking about maintaining as much clean air as possible in their premises. And of course, the more time you can spend in the great outdoors on relaxing strolls or by the sea, the better!
Useful links Find up-to-date guidance on travel, safety, Covid-19 research and more.
RightRooms believes all information to be correct at time of going to press. As guidance, research and facts around Covid-19 are changing constantly, the information provided here is for general information only and does not constitute professional advice. Please check with venues, locations and attractions before travelling.