A portable enclosure (10), easily erectable and collapsible, to provide environment control and prevent contaminants from being released from the enclosure. The enclosure provides a flexible envelope (50) attached to the interior of the space defined by vertical and horizontal supports (12, 16, 17) which can be erected and collapsed. When erected the enclosure functions as an anteroom and has removable panels in the sides and top. In use, the enclosure is sealed against a vertical or horizontal surface to be worked on (57) and a panel (52) from the side of the enclosure is opened and closed to provide access to the surface by the user. When collapsed the enclosure is a package approximately the size of an average golf club bag which is easily portable to another location. Ducting (66, 68) is provided to which negative pressure pumps are connected to maintain negative pressure within the enclosure and draw contaminants into the pump and then into a closed container. In one embodiment, a four-sided flange (144) extends from the rear side of the enclosure to allow sealing of the flange around the doorway and thereby provide a mechanism for isolating the room located interiorly of the doorway.