I think labs have something crazy like 6 full air changed an hour which means they need to essentially pump in 6 or more rooms full of air every single hour and this massive CFM (cubic feet per minute) load generates a large pressure difference in the room so it’s impossible for the unpressurized hallway to contaminate. pretty cool imo

I don’t think it’s about laminar flow all laminar flow relates to is the turbulence or Reynolds’s number of the flow, the reason you want positive pressure is so outside air won’t contaminate due to pressure difference. All that matters is you have air constantly being pumped into the room.