Laminar flow diffusers located in the ceiling immediately above the work area can provide a controlled flow of conditioned supply air with minimal entrainment of residual room air. Coupled with low - levelexhaust inlets, a controlled, low velocity mass movement of air can be maintained.The boundary layer of the air mass is theonly place where any appreciable entrainment of residual room air may occur. With the bound ry layer remote from the work area, the low velocity controlled air mass effectively isolates the work area fromany effects or contaminants of the residualroom air.