Apparatus for concentrating a nebulant comprising a nebulant flow conduit anda counter-flow conduit, or preferably, a plurality of alternating nebulantflow conduits and corresponding counter-flow conduits eg in layered or coaxialarrangement, and wherein at least a portion of the nebulant flow conduit and saidcounter-flow conduits define respective opposed sides of a gas permeable membrane.In use a nebuliser is in communication with the nebulant flow conduit and the nebulantflow and counter-flow are in the same or opposite directions and act to concentratethe amount of active in a droplet eg from 35wt% to 60wt% hydrogen peroxide in waterto disinfect and/or sterilize an article.
