Oxygen Concentrators are medical devices which produce pure oxygen . Air contains 21% oxygen; rest is mostly nitrogen. Concentrators remove the nitrogen, leaving the remaining air 93-95% pure in Oxygen. Oxygen Concentrators deliver oxygen to the patient by means of Nasal canula . Oxygen therapy is typically recommended for people who have ailments, such as breathing problems , lung disease, cancer, or heart problems, which prevent the proper amount of oxygen from circulating in the blood. The amount of time spent doing oxygen therapy may vary; some will require it for a few hours, while some will require a constant therapy.