Five day evaluation of ventilation controls for preventing nosocomial transmission of tuberculosis.

Nosocomial transmission of Mycobacterium tuberculosis (MTb) is a recognized risk to health care workers in the U.S. In 1994, the U.S. Centers for Disease Control and Prevention (CDC) published Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Facilities, 1994. (1) The Guidelines included recommendations for design and operation of Mfb isolation rooms. These recommendations include maintaining a negative pressure differential of at least 0.001 inches water column between the patient room and hallway and excess exhaust ventilation of 50 cubic feet per minute or 110% of supply, whichever is greater. An earlier version of the Guidelines recommended maintaining velocity under the door of the patient room at or above 100 feet per minute.