Importance of ACH and Negative Pressure
Negative Pressure. Positive Results®
The implementation of effective negative pressure containment procedures is critical for isolating particles, bacteria and fungal spores released into the air during facility construction, renovation and maintenance activities. Sensitive patients can be protected in an effective and economical manner by implementing three time-proven negative pressure containment and isolation techniques:
- Establishing a physical containment zone, by enclosing the area in which the contaminants are generated, and sealing off any HVAC exhaust ducts in that area. This is most commonly accomplished by use of prefabricated fixed or portable containment modules that consist of a frame and polyethylene sheeting, or by fabricating a barrier.
- Placing a sufficient number of HEPA filtration devices (HFD) within the contained area to continuously filter particles and contaminants out of the air. Most experts recommend a minimum of between six to 12 air changes per hour (ACH).
- Exhausting HEPA filtered air from the containment area at a rate sufficient to create and continuously maintain negative (lower) air pressure within that area relative to adjacent spaces. Negative pressure ensures that any air that leaks through the physical barrier between the areas will be “clean” air flowing into containment, as opposed to “dirty” air flowing out.