TECHNICAL FEATURE FEA * In most cases, OR personnel are not wearing full coverage gowns and hoods when in close proximity with the surgical site as they would be in semiconductor manufacturing cleanrooms when working with exposed wafers; * Airflow directed at the partially gowned OR personnel can sweep particles toward the surgical site rather than away from it; * The current air system design does not fully isolate and protect the surgical site from contaminants that may be generated in the rest of the OR during surgery. Major strides in yield improvements occurred in semiconductor manufacturing when the wafer was isolated from the rest of the cleanroom. * Ceiling filter or laminar diffuser coverage is not 100% resulting in turbulence between the edge of the sterile field and the perimeter walls. Turbulent areas typically have vertical air currents that circulate particulate. * Air leaves the space through only a limited number of outlets-two to four outlets in only two walls are prescribed-rather than through a perforated floor leading to airflow turbulence in parts of the room and unpredictable particle movement. * Space pressurization is low-only 0.01 in. w.c. (2.5 Pa) to the adjacent space. It has been recognized that when doors are opened, pressurization effectiveness is lost. This is not the case with semi-conductor cleanrooms that operate at higher pressures-up to 0.07 in. w.c. (17.4 Pa) and/or use air locks. * There are many solid objects in the OR that deflect the laminar air leading to unpredictable, random particle movement. In semiconductor cleanrooms, wherever possible, www.info.hotims.com/49801-46 FEBRUARY 2014 ashrae.org ashraE JourNal 21