Self-Contained Breathing Apparatus (SCBA) is a form of respiratory protective equipment that provides the wearer with an independent supply of breathable air from a high-pressure cylinder, allowing safe working in atmospheres that are immediately dangerous to life or health (IDLH). Unlike filter-type respirators, SCBA does not rely on the surrounding air and is therefore used where there may be oxygen deficiency, toxic gases, smoke, or other unknown contaminants.

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This type of equipment is commonly required for high-risk confined space entry into tanks, silos, sewers, shafts, and vessels, as well as during emergency response, maintenance, and rescue operations where hazardous atmospheres may be present or could develop. It is also used in industries such as utilities, manufacturing, chemical processing, and fire and rescue, where personnel may need to enter environments that cannot be made safe by ventilation or other control measures. Because this equipment is more complicated, combined with the fact that incorrect use thereof can have dire consequences, it is highly recommended that users undergo suitable training .