<Tr> <Td> </Td> <Td> This article does not cite any sources . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (December 2009) (Learn how and when to remove this template message) </Td> </Tr> <P> Positive pressure is a pressure within a system that is greater than the environment that surrounds that system . Consequently, if there is any leak from the positively pressured system it will egress into the surrounding environment . </P> <P> Use is also made of positive pressure to ensure there is no ingress of the environment into a supposed closed system . A typical example of the use of positive pressure is the location of a habitat in an area where there may exist flammable gases such as found on an oil platform or laboratory cleanroom . This kind of positive pressure is also used on operating theaters and in vitro fertilisation (IVF) labs . </P> <P> Hospitals may have positive pressure rooms for patients with compromised immune systems . Air will flow out of the room instead of in, so that any airborne microorganisms (e.g., bacteria) that may infect the patient are kept away . </P>

What is the difference between positive and negative air pressure