IN A PRELIMINARY report1a device for supplying a supersaturated atmosphere and high oxygen concentrations has been described. This method of therapy is also known as continuous oxygen-aerosol or cold humidification therapy. The apparatus for this therapy was designed to fulfil the following requirements: (1) to produce a supersaturated atmosphere of nebulized particles (a visible mist) within a Collins Oxyflo Open Top (formerly Burgess-Collins) Oxygen Tent; (2) to maintain an oxygen concentration at 60 vol. % or more, and (3) to provide a means for controlling the temperature within the tent. The following additional attributes were felt desirable: (1) that such equipment should be easily portable and so available anywhere in the hospital or in the home; (2) that the equipment should be simple to operate and maintain, and (3) that the cost of such equipment should be reasonable. The original apparatus consisted of a plastic Vaponefrin nebulizer adapted to