News // Smartwatch

Apple Watch Series 6: How is blood oxygen measured?

The wrist mini-computer was common in childhood cartoons and Hollywood science fiction productions, but technology has allowed us to get closer than ever to having an advanced knowledge and data processor at hand. So it is with the latest Apple Watch Series 6.

The new Apple Watch Series 6 has added some health technologies that are extremely timely, especially in the current context of the pandemic. Many of us are probably even more attentive to our general health. Measuring blood oxygen, along with things like heart rate and body temperature, can be an important indicator of overall health.

What is oxygen in the blood?

Before we get to how, it’s important to understand why. Simply put, the level of oxygen in the blood is the amount of oxygen circulating in the bloodstream. Most of the oxygen in the body is carried in our red blood cells. These cells collect oxygen from the lungs where we breathe it and transport it to all the cells in the body.

The level of oxygen in the blood is the percentage of oxygen in those red blood cells. Knowing how well the blood distributes oxygen is the key to health and well-being. Too little oxygen in the blood can lead to shortness of breath, headaches, dizziness or high blood pressure and will mean that the cells are not getting the “fuel” they need. This can lead to a condition called hypoxemia.

Who needs to measure oxygen in the blood?

Those with medical conditions or compromised immune systems could benefit from maintaining control over their blood oxygen levels. However, elite athletes or people trying to extract maximum performance from their body also like to take into account the level of oxygen in the blood.

How is blood oxygen measured with the new Apple Watch Series 6?

The Apple Watch Series 6 has added a dedicated sensor for measuring blood oxygen levels as part of the reconfigured cardiac optical sensor or small circular glass window that you can see on the back of the watch. The rear window uses red and green LEDs and infrared light projected on the wrist and then measures how much light is reflected back.

This gets a little complicated, but in essence, Apple says that the wrist mini-computer then uses those light measurements to process the color of the blood, which in turn indicates the level of oxygen in the blood: brighter red has more oxygen, while darker red has less.

Set up the Blood Oxygen app on the Apple Watch Series 6

The first step in tracking blood oxygen is to install the dedicated app and it is worth mentioning that the app is only available in certain countries and regions..

Navigate to the App Store on your watch and search for the Blood Oxygen app , then follow the on-screen instructions to download it. Here’s how to measure your blood oxygen:

Step One:  Make sure the Apple Watch is comfortable on your wrist, but not too loose.

Step two:  Open the Blood Oxygen app .

Step three:  Stay still and make sure your wrist is perfectly flat, with your Apple Watch facing up.

Step four:  Press  Start  and hold the arm still for 15 seconds.

Step five:  Tap the Done button .

You’ll get a percentage reading, and this information will also reach the Health app on your iPhone, so you can track data and trends over time. It’s important to know that this app isn’t compatible with older versions of the Apple Watch, and if you try to install it, you’ll only receive an error message.

You can also set up the app to take blood oxygen readings in the background throughout the day. On the iPhone, open the Health app and follow the instructions. If you do not receive a setup request, tap  Browse , then tap  Respiratory  >  Blood Oxygen  >  Set up Blood Oxygen . When you’re done setting up, open the Blood Oxygen app on your Apple Watch to measure your blood oxygen level.