The oxygen self-rescuer is the ultimate breathing apparatus. It is suitable for any situation in which there are problems with the ambient air, as it operates independently of it. While other systems rely on a sufficient amount of oxygen in the air and only need to remove toxins from it, the oxygen self-rescuer does not require additional oxygen in the surrounding air. In theory, it is even conceivable that there is no air to breathe, for example, underwater. (However, the oxygen self-rescuer is not designed for use underwater, so this would be outside its specifications.) Due to its size, it can be carried at all times. The simplest, smallest, and lightest form of the oxygen self-rescuer works with chemically stored oxygen, which is stored in the form of KO2 granules.