Abstract: A wall and ceiling construction system for use in the construction of rooms which can be kept in a sterile and dust free state comprises wall panels having a double skin construction with an air space between opposite skins thereof, the panels being secured together at upstanding marginal regions, possibly with the interposition of fixing posts. The panels include a number of panels which have at least one duct inlet thereinto for communicating the room interior via the interior of the panels with extraction ducts above ceiling level at air outlet spigots. The panels are coved at their transition between the walls and a base of greater width than the thickness of the panel. Depending upon the manner of provision of the duct inlets, in addition to achieving conventional air flow into floor level air inlets directly within the room, it is possible to achieve horizontal air flow or vertical air flow within the room.