Method for treating through-cavities or lumen of tools, in particular medical instruments, wherein the tool is inserted in a passage to a chamber defined by and within a housing wall, wherein the entrance end or proximal end of the tool is situated outside of the housing wall and the exit end or distal end of the tool is situated in the chamber, the tool is held in that position, compressed gas is introduced in the proximal end of the tool in order to press gas through the lumen from the proximal end towards the distal end of the tool while taking along particles present in the lumen.
