Opening the door provided additional air to a smoldering living-room fire and caused the fire to increase in burning rate and flames to extend out the doorway, resulting in high temperatures and heat flows that melted a hole in the mask. Pressure sensor (brass fitting that was mounted on the face of the headform) is visible through the hole in the lens. A self-contained breathing apparatus, or SCBA, 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).