Track the Level of Oxygen in Your Blood
Besides being able to track your heart rate, you can also track the levels of oxygen in your blood.
Granted, this has been an issue for Apple recently, leading to this feature being disabled on new models sold in the US due to a patent dispute. However, you can still find it on new Apple Watch models sold in other countries, and some sold in the US from third-party retailers like Amazon and Best Buy — just be sure you check the model number before you buy.
Except for most Apple Watch Series 9 and Ultra 2 models sold in the US since January 18, blood oxygen monitoring is available on the Apple Watch Series 6 or later and Apple Watch Ultra models, although it’s not a feature of the lower-cost Apple Watch SE.
With this feature, you’ll get a pretty accurate reading of your blood oxygen levels. Generally speaking, anything above the 90% mark is considered healthy, but remember to check with your medical provider.