Abstract: Enclosures having adjustable clean gas flow environments and methods of enclosed pressure differential distribution technology. Specifically, clean gas flow enclosures, which provide for the isolation of materials from airborne micro-particulate contamination. An embodiment of the invention utilizes a small footprint, modular, selectable, clean-gas flow environment for handling and isolating materials. The environment can be a clean room class environment by providing filtered gas from a gas flow generator (12) through a gas filter (13) to a filtered gas flow space (20). An embodiment of the invention provides a first plenum (23) and a second plenum (26) so that both a horizontal filtered gas flow and vertical filtered gas flow may be used separately or in combination within the same filtered gas flow space (20).