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What are blood oxygen levels? The lesser-known important health metric

Blood oxygen levels have come into the spotlight this year because health practitioners are using that metric to check for and monitor COVID-19 cases. But blood oxygen, or SpO2, levels have been used long before COVID-19 as an important indicator for your heart, lung and overall health. Simply put, your blood oxygen level (or SpO2 level) is the amount of oxygen in your blood. This health metric, which is often called the fifth vital sign, is important to monitor in people who have respiratory conditions, COVID-19 included. 

Unlike your heart rate, which you can feel if it gets too high, it's not easy to self diagnose low blood oxygen levels, also called hypoxemia. You might have shortness of breath, but you could also look and feel totally fine. While there have been many people with COVID-19 who experience hypoxemia, many other reasons, including health conditions or environmental factors, can also cause hypoxemia. 

Traditionally, to measure SpO2 you need a pulse oximeter (a device that clips on your finger). But with the new Apple Watch Series 6, you can now monitor blood oxygen with the watch's new blood oxygen sensor and app. 

Next article Everything You Need to Know About Heart Rate Variability (HRV)