In case the blood oxygen levels are too low, the condition is known as Hypoxia. (If the level is as low as 90%) Sometimes, the levels can go as low as 80%, resulting in severe hypoxia, which can be life-threatening.
There can be various reasons for low oxygen levels in the blood which include:
- breathing in high altitudes
- chronic obstructive pulmonary disease (which is the fourth leading cause of death in the United States of America)
- sleep apnoea
- pneumonia, and so on
Medical treatment depends upon the cause of low oxygen levels in the blood.
There are ways of increasing oxygen in the blood through some lifestyle changes.
Or you can have a look at: Blood Oxygenation Enhancement & Detox
Bound-Oxygen Products 