A plasma treatment device comprising: a treatment chamber for receiving an item to be treated, the chamber comprising at least one conformable wall for forming a volume in which to receive the item; a pump operably connected to the treatment chamber, configured to remove ambient air in the treatment chamber, thereby creating a vacuum that causes the conformable wall to collapse and at least partially conform to the item, so as to reduce the volume of the treatment chamber to a working volume of ambient air, and wherein the ambient air not retained in the working volume of air is excess ambient air; at least one effluent chamber (3,2), operably connected to the pump, configured to receive and sequester the working volume of ambient air from the treatment chamber and from which the working volume of ambient air is returned to the treatment chamber by the pump during each of multiple treatment cycles; and a plasma generator configured so that the working volume of ambient air in the at least one effluent chamber (3,2) passes the plasma generator as it is moved into the treatment chamber by the pump during each of the multiple treatment cycles, whereby at least a portion of the working volume of ambient air returned to the treatment chamber during each treatment cycle is converted to plasma prior to entering the treatment chamber, such that the plasma concentration of the working volume of ambient air increases during each treatment cycle, wherein the plasma generator is optionally positioned between the pump and the treatment chamber, wherein the pump is configured to remove the excess ambient air from the treatment chamber by having it pumped to the ambient environment or another effluent chamber (3,1), operably connected to the pump, is configured to receive and sequester the excess air. a treatment chamber for receiving an item to be treated, the chamber comprising at least one conformable wall for forming a volume in which to receive the item; a pump operably connected to the treatment chamber, configured to remove ambient air in the treatment chamber, thereby creating a vacuum that causes the conformable wall to collapse and at least partially conform to the item, so as to reduce the volume of the treatment chamber to a working volume of ambient air, and wherein the ambient air not retained in the working volume of air is excess ambient air; at least one effluent chamber (3,2), operably connected to the pump, configured to receive and sequester the working volume of ambient air from the treatment chamber and from which the working volume of ambient air is returned to the treatment chamber by the pump during each of multiple treatment cycles; and a plasma generator configured so that the working volume of ambient air in the at least one effluent chamber (3,2) passes the plasma generator as it is moved into the treatment chamber by the pump during each of the multiple treatment cycles, whereby at least a portion of the working volume of ambient air returned to the treatment chamber during each treatment cycle is converted to plasma prior to entering the treatment chamber, such that the plasma concentration of the working volume of ambient air increases during each treatment cycle, wherein the plasma generator is optionally positioned between the pump and the treatment chamber, wherein the pump is configured to remove the excess ambient air from the treatment chamber by having it pumped to the ambient environment or another effluent chamber (3,1), operably connected to the pump, is configured to receive and sequester the excess air.