Abstract: A vacuum adherent face mask unit is provided having (a) a face mask for enclosing the nose and mouth of humans. The mask has (i) a mask body having a periphery and defining a chamber from and into which a person may inhale and exhale gases, and (ii) a bladder attached to the periphery of the mask body. The bladder has a face engaging region for engaging the face of a human and encircling the chamber, and has a plurality of perforations spaced around the face engaging region. The unit also has (b) vacuum means for producing a subatmospheric pressure in the bladder when said mask is in engagement with a human face. The vacuum is preferably created by a battery operated vacuum pump, and optionally may be created and/or augmented by the wearer applying suction to a check valved pipe extending from the bladder to the chamber. Monitoring the level of vacuum within the face seal bladder provides a means for advising the wearer of the unit the status of fit in real-time.