Negative pressure flow
Negative pressure flow is an isolation technique used to prevent air from flowing outside of the room or lab. The lab or isolation room will have a lower pressure compared to the one outside. Remember that air always flows from high to low pressure. Therefore, airborne contagious agents won't escape the room or lab.
The pressure of the lab is shown on a readout just outside the lobby or anteroom. The lab's pressure should be between -30 Pa and -50 Pa. The air pressure differential in the lab and lobby or anteroom is approximately -12.5 Pa.
Read more: