rosie1959
Well never heard that one Growstuff Couldn’t tell you which way they open but seems to have worked very very low incidences of Covid
A few little darlings moaning it was cold till they got the balance right but no big outbreaks
Well, it's been stated a number of times that bottom opening windows can contribute to the spread of virus droplets. If somebody sitting near a window is infected, incoming air will blow exhaled breath around the room.
Top opening windows bring cooler fresh air into a room. I'm sure we all remember that hot air rises, so infected air will rise and be replaced by clean air.
The main source of transmission is water droplets. The heavier ones will quickly drop to the floor if not blown around and will soon become inactive. The smaller, lighter ones rise and will linger, if there is no escape for them.
Ideally, classrooms should have HEPA filters which are regularly cleaned.