TECHNICAL FEATURE incorporated into a typical "state-ofthe-art" semiconductor manufacturing cleanroom. To understand how we can use cleanroom technology to improve contamination control in a surgical suite it is important to understand the differences between their respective design elements. The following attributes represent a typical Class 10 (ISO M2.5) Cleanroom: * Ceiling height (raised floor to filter ceiling) 12 ft (3.7 m); * 25% minimum/100% maximum HEPA filter coverage (% of ceiling area); * 99.9995% HEPA filters, ceiling mounted; * Air recirculation change rate of ~ 90 per hour - 360 per hour; * Perforated raised floor for optimal vertical laminar flow; * Filter face velocity of 72 fpm (0.37 m/s); * Room pressurized to 0.07 in. w.c. (17.4 Pa) above dirty adjacent space; * Full coverage gowns (Figure 1, eyes exposed but with safety glasses, Page 18); helmets with battery-powered fan keeping helmet "negative" used where wafers are exposed to factory environment; * Further product isolation within mini-environments ~ Class 1 (ISO M1.5) or better; * Current product line width 0.022 micron (millionth meter); damage can be caused by a particle size ~ 0.002 - 0.004 micron diameter; and * Control over all aspects of contamination in environment and materials used in manufacturing. Operating Room Design www.info.hotims.com/49801-32 20 ashraE JourNal ashrae.org The following attributes are based primarily on Standard 170-201313 FEBRUARY 2014 minimum guidelines for a modern OR sized 20 ft × 20 ft (6.1 m × 6.1 m): * Ceiling height between 9 ft and 12 ft (2.7 m and 3.7 m); * Laminar flow diffuser ceiling air supply grid; * 99.97% efficient HEPA filters either upstream of the ceiling grid or part of the ceiling grid; * Ceiling grid size between 6 ft × 8 ft (1.8 m × 2.4 m) and 8 ft × 8 ft (2.4 m × 2.4 m) (12% to 16% ceiling coverage); * Up to 30% of the ceiling grid area can be devoted to non-airflow delivery (i.e., boom mounts, lights); * Low wall-mounted return grilles; at least two, 8 in. (203 mm) above the floor in opposite corners; two additional diffusers may be installed near the ceiling in the walls; * Air change rate of 20 to 25 per hour of which 3 to 4 ach are from outdoor air; * Laminar diffuser array face velocity of 25 to 35 fpm (0.12 to 0.18 m/s); * Room pressurized to 0.01 in. w.c. (2.5 Pa) positive to the adjacent space; * Smocks/scrubs with caps and double gloves - some exposed skin allowed, Figure 2, Page 18. * Typical particle size carrying bacteria ~ 10 micron diameter; and * No known method to fully control infection from bacteria in OR. Summarizing the previous hospital OR design and where it differs from semiconductor manufacturing cleanrooms. * Hospital ORs are not particleand bacteria-free even when using the prescribed methods of air handling; * The particles that carry bacteria emanate either from personnel in the room or from the patient or products introduced into the OR;