kiterboy said..Bear in mind, he supposedly caught it while sitting in a chair, down the hallway from a person infected with this extra-hyper-contagious UK strain of the virus.
The hotel where the security guard became infected is well known to me!!
I worked there when it was first built [as "THE ORCHARD HOTEL"]
My role was in the engineering department with a very large part of my job for 5 1/2 years being looking after the aircon system.
In the early days, this involved a lot of fine tuning, balancing of the air supply, modifying the impractical hybrid pneumatic + computerised control system so it would actually work, fault finding etc.
While the air con's control system has probably been upgraded from the original Honeywell pneumatic system to a more efficient and modern electronic system - I imagine that the basic ducting of supply and return air will still be the original design.
The filtered incoming air is pumped into each room and the used air [return air] then passes through a duct over the entry door and out into the corridor where it is drawn into the return air shafts near the lifts.
Normally, a percentage of this air is recycled so as to reduce the cost of cooling needed for the building.
With the hotel being used for quarantine - I would hope that the recycling of used air is blocked off and only fresh air supplied to the rooms.
So, in a nutshell - the air being supplied to a room that has an infectious person, passes down the corridor on the way to the return air shafts.
Anyone in that corridor is totally surrounded by potentially contaminated air and has no option but to breathe that air.
Even if the guards and staff are using masks and face shields - there would be no guarantee of safety!