According to World Health Organization’s definition, an oxygen level between 95 – 100% is normal. Levels under 94% should be evaluated by a doctor, while levels below 90% are considered a clinical emergency and require immediate medical attention.

An oximeter is a portable device that can be used to check blood oxygen levels by looking at how much light is absorbed by your blood.

The level of inaccuracy may be small. Factors such as poor circulation, skin thickness can affect the  accuracy.