Measurement

• Levels of blood oxygen are measured using an oximeter, which is attached to your finger, or through a blood test using one of the arteries.
  
  

Results

• According to the Mayo Clinic, the blood oxygen level test should show at least a 95 percent level. Levels between 80 percent and 94 percent are considered low but anything lower is a sign of hypoxemia.
  
  

Causes

• Changes in normal blood oxygen amounts can be caused by chronic obstructive pulmonary disease (COPD), anemia, shock, sleep apnea, pneumonia, carbon monoxide and almost any health condition that affects oxygen or red blood cell levels.
  
  

Complications

• When blood oxygen levels drop too low, you may experience shortness of breath, confusion and fatigue.
  
  

Prevention

• Levels can be kept normal if you do not smoke and if you strengthen your lungs by doing cardiovascular exercises.