Related media at Wikimedia Commons: Works on the topic NIOSH at Wikisource Works on the topic OSHA at Wikisource A self-contained breathing apparatus (SCBA) is a respirator worn to provide an autonomous supply of breathable gas in an atmosphere that is immediately dangerous to life or health from a gas cylinder.

The term self-contained means that the SCBA is not dependent on a remote supply of breathing gas (e.g., through a long hose).

Other early attempts included the French designed "Apparatus Aldini" which was an asbestos and woven wire mask which attempted to provide the user with a small amount of trapped clean air to breath and an English designed closed helmet that pumped clean air across a pane of glass to reduce breathing condensation.

[failed verification][5] Paul Hashagan also notes that, in 1863, A. Lacour developed and patented the "improved breathing apparatus".

[5] Throughout the 1800s, other SCBA-like devices were developed by various people[failed verification] including a closed-circuit rebreather designed by Bernhard Draeger.

[8] Close to the mid 1900s and post WWII, Scott Aviation began developing an SCBA designed specifically for firefighting use.

It is used when a longer-duration supply of breathing gas is needed, such as in mine rescue and in long tunnels, and going through passages too narrow for a big open-circuit air cylinder.

[9] There are two types of closed-circuit SCBA according to NIOSH: To reduce pressure buildup from use, a pressure-relief valve with saliva trap is included.

[9] Self-contained self-rescue devices are also closed-circuit SCBAs, working on the same principles, being designed for emergency use in mines, and lasting about one hour.

[13] Z88.2–2015 notes that "open-circuit SCBA are equipped with a full facepiece or tight-fitting hood", and, like closed-circuit SCBAs, can be configured in pressure-demand or demand mode.

[citation needed] An open-circuit rescue or firefighting SCBA has a full-face mask, also called the face-piece, a demand regulator, air cylinder, pressure gauge, (sometimes with an integrated PASS device), and a harness with adjustable shoulder straps and waist belt which lets it be worn on the back.

The fitness and level of exertion of the wearer affect breathing rate, and result in variations of the actual usable time of the SCBA.

[citation needed] Air cylinders are made of aluminium, steel, or of a composite construction (usually glass or carbon-fiber wrapped.)

SCBAs used by the fire service also incorporate other features such as a PASS (personal alert safety system), which is a device that emits a loud alarm should the firefighter manually activate it or remain motionless for a certain amount of time.

[21][non-primary source needed] Other features may include Bluetooth connection to voice amplifiers or portable radios, digital heads-up displays, built-in infrared cameras, ePAR (electronic personal accountability report) system, point of view video recording,[22] and digital screens allowing the firefighter to more easily check their air supply.

In some of the most hazardous conditions, SCBAs can be worn in conjunction with gas tight suits, which also aids in decontamination procedures.

[citation needed] In the United States and Canada, SCBAs used in firefighting must meet guidelines established by the National Fire Protection Association, NFPA Standard 1981.

Similarly, the National Institute for Occupational Safety and Health (NIOSH) has a certification program for SCBA that are intended to be used in chemical, biological, radiological, and nuclear (CBRN) environments.

Shoulder harness straps of heavy SCBA can reduce free motion of the thorax which affects breathing.