Abstract: A treatment system includes a vaporizer, a tent for maintaining a high humidity environment in a chamber around at least the upper body of an individual under treatment, and a flexible conduit from the vaporizer to the chamber. The tent includes a supporting framework and a porous fabric supported by the framework. The fabric, preferably a polyester tricot, consists of multifilament strands woven to provide a porosity of about fifty percent. So constructed, the fabric is air permeable, yet tends to block a substantial percentage of moisture droplets suspended in the air, thereby increasing the relative humidity inside the therapy tent to a value substantially above ambient relative humidity, for example over ninety percent while ambient levels outside the tent remain at about fifty percent. As a result, a therapeutic, high humidity environment is maintained about the patient, without the need for oxygen supplies, pumps, blowers or other special equipment.