Figure 1: Schematic representation of cleanroom IVF facilities, including airflow patterns and filtration units. The air handling ventilation unit room has a roof-top air-handling unit that draws outside air through coarse and charcoal prefilters before it enters into the main ventilation unit. A free-standing main ventilation unit pulls prefiltered outside air and cleanrooms' return air through coarse filters, past a 16-unit potassium permanganate impregnated pelletized coal-based activated carbon filters, and then through fine dust filters. Lastly, filtered air enters the cleanrooms through high-efficiency particulate air (HEPA) filter diffusers. Floor and ceiling-level vents in the cleanrooms' return air to the main ventilation unit, to be remixed with the existing air. Differential positive pressure is maintained between rooms. The embryology laboratory/anteroom is positive to the operating room, which is positive to both the embryo transfer room and the dressing room/hallways. Reprinted from Esteves and Bento, Reprod Biomed Online 2013; 26: 9-21, with permission from Elsevier.