An apparatus and method for the shaping of plastics material pre-forms into plastics material containers with at least one blow moulding station which is arranged on a conveying device rotatable about a pre-set axis of rotation (D). The blow moulding station has a blow mould and this blow mould forms a cavity in the interior of which the plastics material pre-forms are capable of being expanded by being acted upon with a gaseous medium to form the plastics material containers, with a stressing device, which acts upon the plastics material pre-forms with the gaseous medium in order to expand them, and with a clean room, which surrounds the blow moulding station at least in part. The clean room is bounded off from an environment by at least two walls which are movable relative to one another.