Sometimes referred to as a compressed air breathing apparatus (CABA), or simply breathing apparatus (BA), is a device worn by rescue workers, firefighters, and others to provide breathable air in an “Immediately Dangerous to Life or Health” atmosphere (IDLH). When not used underwater, they are sometimes called industrial breathing sets. The term “self-contained” means that the breathing set is not dependent on a remote supply (e.g., through a long hose). If designed for use under water, it is called SCUBA (self-contained underwater breathing apparatus).