A face shield may also be used in conjunction with a half-mask airline respirator for protection against body fluids. Since this type of respirator exhausts air contaminated by the user it should not be worn during sterile procedures. The exhalation valve allows droplets and particles to escape through the valve, potentially spreading any contagious particles to the surgical field by the health care worker. Advantages The supplied-air respirator is much more protective because it provides a positive pressure in the facepiece and almost all leakage is outward. Drawbacks A source of breathing air is needed and the airline hose may limit movement.
Communication can be difficult.
These respirators are usually available in three sizes.