This invention relates to an aseptic processing workstation comprising a processing chamber and an airflow circuit passing through the chamber. The circuit comprises an air supply fan, an air return fan and a restriction element. 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 of the air supply fan and the air return fan to the chamber. The workstation further comprises an air inlet fluidly connected at a first connection point to the circuit via inlet valve means. The first connection point is located between the restriction element and the air supply fan. The workstation further comprises an air outlet fluidly connected at a second connection point to the circuit via outlet valve means. The workstation further comprises control means for independently controlling the speed of the air supply fan and the air return fan.