Continued successful operation of open-fronted microbiological safety cabinets in a force-ventilated laboratory.

The considerable refinements necessary to enable Class I and II microbiological safety cabinets to operate in a force-ventilated laboratory and to meet appropriate safety criteria have been reported previously. The continued successful operation of such cabinets without a deterioration of operator protection is described. The performance of two Class II units, one meeting and one failing the current British Standard applied to four head KI-discus testing, is compared and discussed. In addition, some further potential difficulties within the environment, which could compromise cabinet containment, are highlighted.