Apple has included a new blood oxygen monitoring sensor in the Apple Watch Series 6. There’s a new Blood Oxygen app to go along with it that you can use to measure your blood oxygen app. Before you can use the blood oxygen sensor though, you will have to set it up. For this, open the Health app on your iPhone where you should automatically get the prompt to set up the blood oxygen app. If not, go to the Browse tab followed by Respiratory > Blood Oxygen > Set up Blood Oxygen. After this, you can open the Blood Oxygen app to measure the blood oxygen levels using your Apple Watch. Whenever you take a measurement, ensure that the watch is sitting snuggly on your wrist.