A suspension ceiling for clean room installations is disclosed. The ceiling has a suspended ceiling support structure having a plurality of grip openings including a vertical member between each grid opening and flanges extending horizontally from each vertical member so as to form a horizontal surface around a periphery of each grid opening for peripherally supporting a ceiling insert therein. At least one ceiling panel is positioned in a grip opening and peripherally supported by the flanges. An edge cap sealingly engages the ceiling panel edge surface for inhibiting particle emission therefrom. The edge cap comprises an elongated rigid or semi rigid strip of generally U-shaped cross-section having first and second horizontal portions respectively compressively engaging the periphery of the back and front ceiling panel horizontal surfaces and a vertical portion joining the first and second horizontal strip portions adjacent the ceiling pane, edge surface. A gasket is secured to the second horizontal strip portion and compressed against the flange surface to form a seal around the periphery of the grip opening. There is also disclosed an assembly for sealing the edge of the grid suspension ceiling panel, and a prefabricated ceiling panel including the edge sealing assembly.