When originally introduced for use at the turn of the century, the primary function of the surgical mask was to prevent the migration of microorganisms residing in the nose and mouth of members of the operating team to the open wound of the patient. As technology developed new materials and designs, their filtering efficiencies gradually improved. However, there is no standard test method for assessing that capability, and its influence on the rates of surgical-wound infection has yet to be demonstrated. Quite to the contrary, both in-vitro and in-vivo studies indicate that a mask may not be universally necessary in today's surgical environment.