Powered air-purifying respirator

A powered air-purifying respirator (PAPR) is a type of respirator used to safeguard workers against contaminated air. PAPRs consist of a headgear-and-fan assembly that takes ambient air contaminated with one or more type of pollutant or pathogen, actively removes (filters) a sufficient proportion of these hazards, and then delivers the clean air to the user's face or mouth and nose. They have a higher assigned protection factor than filtering facepiece respirators such as N95 masks. PAPRs are sometimes called positive-pressure masks, blower units, or just blowers. The modularity of PAPRs allows them to be customized for different working environments. Regardless of type, a PAPR consists of: some kind of headgear (mask or hood), a powered (motor-driven) fan which forces incoming air into the device, a filter (or multiple filters) for delivery to the user for breathing, and a battery or other power source. The mask may be hard and tight-fitting, or flexible and loose-fitting. The former affords a higher level of protection, but is less comfortable. Tight-fitting PAPRs require a fit test, while loose-fitting ones do not. This makes loose-fitting PAPRs useful when a fit test for a tight-fitting respirator cannot be successfully passed, for example when facial hair is present. Masks may be reusable or disposable. Some masks allow the full face to be seen by others, aiding in interpersonal communication. The fan, filter, and power-pack may be carried around freely by the user, often secured by a belt around the waist. Alternatively, with certain units, the air is fed to the user via lengthy tubing while the fans and filters are remotely mounted. PAPRs have low breathing resistance, unlike filtering facepiece respirators such as N95 masks. A PAPR may have adjustable air flow rates for added comfort. While they are often referred to as positive pressure masks, they are not true positive-pressure devices as overbreathing can overcome the pressure supplied by the fan.