COVID-19 has affected millions of people over the past year and a half. One thing that is quite clear is that the virus attacks the lungs of the infected, causing many to exhibit symptoms of severe pneumonia and, in turn, low blood-oxygen levels.

Besides professional medical equipment, seen in hospitals, used to measure oxygen saturation, in recent months, pulse oximeters and smartwatches with SpO2 tracking functions have become a way for many people to monitor their own health.

A medical expert says, however, that the pulse oximeters can only show if oxygen saturation is low, and are not the best way to determine COVID-19 symptoms.