Page:Niosh tb guidelines.pdf/21

Rh

The fundamental strength of the control hierarchy is that it minimizes the likelihood that prevention will "break down" to the extent that results in a hazardous exposure to workers. The control hierarchy for a recognized hazardous source proceeds as follows:

1. Under ordinary circumstances, the most effective and reliable control method is substitution of a less hazardous substance or source of exposure for the more hazardous one. Obviously, when the source of a hazardous exposure is a person with infectious tuberculosis, "substitution" as a potential control method is not possible.

2. The next most effective approach is to prevent or contain hazardous emissions at their source. In the health-care setting, this is best implemented through administrative controls (e.g., rapid identification, early treatment, and isolation of potential tuberculosis transmitters; limiting worker access to acid-fast bacilli (AFB) isolation rooms; other isolation precautions). Other administrative controls might include providing necessary services and procedures (e.g., portable X-ray units) in the room of a confirmed or potential tuberculosis transmitter rather than moving the infectious person to the service. Additionally, engineering controls should be used (e.g., negative-pressure ventilation for AFB isolation rooms to contain any airborne hazard to these rooms; booths, hoods, tents, or other devices for containing droplet nuclei at the source–i.e., a person with infectious pulmonary tuberculosis).