The purpose of PAPR systems (powered air purifying respirator) is to filter ambient air in a way that ensures workers are breathing safe, healthy air at all times. PAPR systems use battery-powered blowers to blow ambient air through a HEPA filter into the facepiece of the device by using the blower to create an air-to-air flow. In contrast to SCBAs (self-contained breathing apparatus), which rely on canisters for their breath supply, a PAPR respirator filters ambient air. Since they are more comfortable to wear over an extended period of time, they are generally more preferred over SCBAs. PAPR systems are generally recommended to be used only in instances where there is no immediate danger to life or health (IDLHs).
In environments in which the air is contaminated, dangerous, or uncomfortable, supplied air respirators (SARs) can be worn by workers as a personal protective equipment (PPE). The supply of air is performed continuously or in response to a demand through the use of cylinders, pipes, compressors, air pumps, air purifiers, or surface supply hoses connected to air lines, compressors, air pumps, air purifiers, or surface supply hoses. With the aid of a hood, mask, or mouthpiece, workers are able to breathe ambient pressure air during their workday.