PAPR (powered air-purifying respirator) systems filter ambient air to provide workers with safe, breathable air. PAPR systems have a battery-powered blower that passes ambient air through a HEPA filter into the facepiece. Because PAPR respirators filter ambient air, they can be worn for longer periods of time than SCBA (self-contained breathing apparatus) systems that use air canisters. PAPR systems are suitable for use only in non-IDLH (immediately dangerous to life and health).