A flexible porous non-pollutive tube, wherein the walls of the tube are made by tapes formed by interlaced textile fibers, and to which activated charcoal is added, in agglomerate, powder or granulated form, and the textile tapes being wound over the charcoal and glued among the charcoal in the helical direction, forming an air conducting acoustic flexible helical pipe which is a part of a combustion engine's intake system used by the automobile industry, and adding the activated charcoal in the walls or in the pipe's external or internal lining.