What does pressure control do when it involes respiratory?

presuure control means the amount of air present in atmosphere if there is not enough air it would certainly affect breathing.





on hilly areas the air pressure is low due to which it becomes tough to breathe also sometimes causes bleeding in nose since the ouside pressure is low while its high in our body which results in bleedingWhat does pressure control do when it involes respiratory?
What does INVOLES mean? Someone help me here.