Zoned exponential, vertical and horizontal ultra-clean laminar airflows. No differences in bacteriological efficiency.

We compared the novel zoned exponential ultra-clean operating room ventilation, needing no extra side-walls with the traditionally used ultra-clean air systems having vertical or horizontal laminar airflow, but requiring extra side-walls. The three units were evaluated with regard to elimination of particles with focus on airborne and sedimenting bacteria-carrying particles (colony forming units, cfu) during rigidly standardized sham operations. Although minor differences were recorded inside the ultra-clean airflows, the three systems were comparable with regard to bacteriological efficiency and ensured a low air and surface contamination (0.05-4 cfu/m3 and 7-72 cfu/m2/h, depending on the site of sampling). We conclude that all three systems fulfilled well the criteria for ultra-clean air (< 10 cfu/m3), but that exponential airflow is the most versatile alternative, as additional side-walls around the operating area can be omitted.