This invention relates to an aseptic processing workstation comprising a processing chamber (12) and an airflow circuit (33) passing through the chamber. The circuit comprises an air supply fan (28), an air return fan (29) and a restriction element (35), i.e. a filter to remove sterilant from the circulating air. The chamber is located in the circuit between the air supply fan and the air return fan. The restriction element is located in the circuit on the other side. The workstation further comprises an air inlet (26) fluidly connected at a first connection point to the circuit via inlet valve means (46). The workstation further comprises an air outlet (27) fluidly connected at a second connection point to the circuit via outlet valve means (49). The workstation further comprises control means for independently controlling the speed of the air supply fan and the air return fan. This allows to independently vary the pressure and air flow through the chamber, i.e. having negative or positive relative pressure inside the chamber.
