A normal oxygen level for a patient suffering from COPD is between 95 and 100 percent, according to About.com. Although some people are able to function normally with an oxygen level as low as 90 percent, a doctor should always be consulted with regard to optimal saturation level.
When the oxygen level falls below normal values, a person should use an oxygen concentrator or an oxygen-gas cylinder to restore the saturation level and improve breathing, states WebMD. Undergoing a long-term oxygen treatment rectifies the low oxygen levels, reduces the shortness of breath and provides the patient with more energy. This type of therapy is typically administered for 15 hours per day at the minimum.