How to Use Apple Watch Blood Oxygen Sensor.
Blood oxygen measurement is the flagship health-related feature of the next generation of Apple Watch models. This is an estimate of how much oxygen the red blood cells carry from the lungs to other parts of the body.
This blog post explains how the Apple Watch Blood Oxygen Sensor measures blood oxygen levels. Plus, learn how to set up the Blood Oxygen app on your new Apple Watch and iPhone.
How Apple Watch Measures Your Blood Oxygen
Apple Watch Series 4, Series 5, Series 6, and Series 7 feature optical heart rate sensors that measure your heart rate. However, the heart rate sensors in Apple Watch Series 6 and Series 7 (and possibly newer models) can measure both heart rate and blood oxygen levels (also called oxygen saturation levels).
When measuring blood oxygen, your Apple Watch illuminates your wrist with bright red and green LEDs and infrared light. Blood reflects red, so photodiode sensors measure the amount of red light reflected from blood on your skin.
Here’s how the Apple Watch Series 6 and Series 7 determine how oxygenated your blood is. Generally, the more red light your blood reflects, the higher the oxygen content in your blood.
How to Set Up Apple Watch’s Blood Oxygen Feature
Blood oxygen measurement is disabled by default on compatible Apple Watch models. To use this feature, turn on blood oxygen measurement on your Apple Watch. Then set up the iPhone Health app to get blood oxygen data from your Apple Watch.
Set up the Blood Oxygen app
Turning on blood oxygen measurement in Apple Watch settings activates the Blood Oxygen app.
Open the Settings app on your Apple Watch, tap Blood Oxygen, and turn on Blood Oxygen Measurements.
You can also set up your Apple Watch Blood Oxygen remotely from the Watch app on your iPhone. Open the Watch app, go to My Watch > Blood Oxygen, and turn on Blood Oxygen Measurements. Then choose whether you want the Blood Oxygen app to take background measurements in theater and sleep modes.
Note. You won’t find Blood Oxygen on Apple Watch if the service isn’t available in your country or region. Change the country in the App Store if you can’t wait for Apple to release the app in your country. Visit this watchOS Feature Availability page to view the countries in which the Blood Oxygen app can be used.
Set up blood oxygen measurement in the Health app
Apple Watch blood oxygen measurements are recorded in the Health app on iPhone. After you turn on blood oxygen measurement on your Apple Watch, follow these steps to turn on blood oxygen measurement in the Health app:
Open the Health app on your iPhone, enter your personal health information, and tap Done to set up your health profile.The Health app should prompt you to turn on blood oxygen if your Apple Watch and iPhone are connected. Click Enable to continue.
If you don’t receive this prompt, go to the Overview tab, click Respiratory Organs, select Blood Oxygen, and click Enable. Then proceed to the next section to take your first blood oxygen measurement.
Can’t find blood oxygen in the Health app? Update your Apple Watch and iPhone to the latest watchOS and iOS respectively.
It should be noted that blood oxygen measurement is only available to users aged 18 and over. You won’t find the Blood Oxygen app in the Health app if your health profile is under 18 years old. If you are over 18, enter your age in your health profile and check the Blood Oxygen app again.
Tap the profile icon in the Summary tab, select Health Information, tap Edit, and tap the Date of Birth row. Enter the correct birth details and click Done.
Close and reopen the Health app and follow step 3 above to turn on blood oxygen.
How to Take Blood Oxygen Measurement
Put your Apple Watch on your wrist and make sure the band is snug but comfortable. Move your Apple Watch above your wrist so that the base is on your skin at all times. Apple recommends that you place your watch 1-2 inches from your wrist.
Place your hand (on your lap, table, or any stable surface), hold your Apple Watch face up, and don’t move.
Press the Digital Crown to open the watch’s home screen and tap the Blood Oxygen app icon.If this is your first time using the app, tap “Next” for tips and tricks on measuring.Press “Start” to start measuring blood oxygen and keep your hand still until the app completes the 15 second countdown. You will see your blood oxygen level on the results page.
Note. Blood oxygen level or oxygen saturation level (abbreviated as SpO2) is measured as a percentage (%).
Tapping with fingers or slight movement of the hand interrupts the measurement. Retry the test if the app displays a “Blood oxygen level could not be measured” error on the results page. This time adjust your Apple Watch to fit and keep your hand on the table.
What’s the “Normal” Blood Oxygen Level?
The Food and Drug Administration (FDA) estimates blood oxygen levels for healthy people to be between 95% and 100%. However, people with lung and heart disease may have low blood oxygen levels (80-90%).
We should also mention that certain environmental and physical factors can temporarily lower blood oxygen levels. For example, sleeping, holding your breath, or being at high altitudes (in mountains or on airplanes) reduces the amount of oxygen in your blood. This is because the amount of oxygen in the lungs varies with time, activity, and location.
The Health app has an educational article about blood oxygen. Read the article to learn about the importance of blood oxygen for your health.
Open the Health app, go to Overview > Respiratory System > Blood Oxygen, and then tap See Blood Oxygen Level.
View Blood Oxygen Readings
Open the Health app, tap All Health Data, and select the Blood Oxygen card. Below the graph, you will see the last measurement of oxygen in the blood.
Alternatively, go to Overview > Respiratory Organs and tap on a recent blood oxygen measurement.
Scroll down the page and click “Show All Data” to view all measurements with date and time stamps.
Should You Trust Apple Watch’s Blood Oxygen Measurement?
You should, but not for medical purposes. The smartwatch is not FDA certified for measuring blood oxygen levels. In addition, the color and infrared LEDs of the Apple Watch sensors do not penetrate the skin or blood. Instead, the sensor measures the oxygen content in your blood using the amount of (red) light reflected from your skin’s blood.
Changes in the environment or skin temperature may affect the measurements of the Blood Oxygen app. Therefore, it is very difficult to obtain an accurate measurement of oxygen in the blood in the cold. Tattoos can also block light from Apple Watch sensors and cause measurement errors.
Some reports prove that Apple Watch blood oxygen measurements are unreliable and can be misleading. Apple also warns that Apple Watch blood oxygen measurements are not intended for medical use. This feature, according to Apple, is only for “general fitness and wellness.”
FDA-approved prescription oximeters used in hospitals provide more accurate blood oxygen measurements. Over-the-counter (OTC) oximeters can provide a near-accurate estimate of blood oxygen saturation, but they are not FDA certified and cannot be used clinically.
The blood test remains the best and most accurate method for determining blood oxygen levels. If you have a serious medical condition that requires you to measure your blood oxygen levels, don’t use your Apple Watch. Instead, talk to your doctor or visit a medical lab for a blood test.
How to Use Apple Watch Blood Oxygen Sensor
How to Use Apple Watch Blood Oxygen Sensor