Depending on the area seen in an individual picture, brown, yellow and green continents can be seen or parts of Earth can be covered by white clouds. Earth is by far the most dynamic planet when seen from space.
Oxygen therapy is a medical treatment. It must be prescribed by a doctor. For people with COPD, oxygen therapy can be a helpful part of their treatment plan. The prescription your doctor writes will include: If you need oxygen for rest, exercise and/or sleep, and how much in liters per minute (lpm) for each activity.
Without more details, I'm going to treat this case as arising from chronic obstructive pulmonary disease (COPD) which is the most common cause of hypoxia. In that context, 85-90% spans very important numbers. 85% absolutely requires supplemental oxygen, whereas 90% does not. Generally oxygen is not covered by insurance and not prescribed unless the saturation is <89% (and we inpatient doctors need a result from the day of discharge and not before).