Post-operative infections after surgery can be decreased by the use of efficient ventilation with clean air. In this study, we investigated three types of operating room ventilation: turbulent mixed airflow(TMA), laminar airflow (LAF) and a new type of ventilation named temperature controlled airflow(TcAF). Measurements of airborne bacteria were made during surgery and compared with values calculated by computational fluid dynamics (CFD). The results show that LAF and TcAF are most efficient in removing bacteria around the patient. With LAF, there are large differences in bacterial loads, depending on location in the room.