Apple has introduced the ability to monitor our blood oxygen level, which is useful when you have various health issues. It is straightforward to take reading of blood oxygen level. The device has IR, red and green LEDs that shine onto your wrist and the reflected light will be measured. A special algorithm uses the colour of your blood to determine its oxygen level. If your blood is bright red, it has higher oxygen level and if it’s darker, it contains less oxygen. A healthy person has an oxygen level of between 95 and 100 percent. The sensor can measure the level to as low as 70 percent. Although this feature isn’t for medical use, you will know when your blood oxygen level getting is lower than usual. You may rectify it by performing deep, slow breathing technique or by calling your doctor.

Unfortunately, the blood oxygen technology isn’t always reliable and accurate. These sensors are very sensitive and it is possible that minor movements will reduce accuracy. If you continue getting a warning that measurements have been unsuccessful, it should be relatively easy to fix. This feature won’t work if you form a fist with your fingers or your arm hangs down. Your wrist must face up and be flat on a surface, while fingers are relaxed and open. Make sure your Apple Watch isn’t too tight or loose. It should fit well and snugs comfortably against your wrist. If your Apple Watch is on the wrist bone, you should reposition it lower. Make sure that your wrist is more stable, by putting it on a table or any flat surface. For 15 minutes, you should sit sill and minimize any unnecessary movement.

While the sensor is measuring your blood oxygen level, make sure that you don’t engage with the device. Even a minute movement may disrupt the reading accuracy. Other than improper arm posture and unnecessary movements, there are other causes of inaccurate reading. If you have dark tattoos under the Apple Watch, the light may have problem penetrating the skin to check your blood’s colour. There’s no solution to this problem, unless there’s part of your wrist that doesn’t have dark-coloured tattoo. Light tattoos may still allow the light to measure your blood oxygen level, so it’s best to leave a good portion of your wrist without tattoo. When you are outdoors during winter, the sensor may fail to work. You need to find a warmer to place and do measurement when the Apple Watch unit has reached room temperature.

Slow blood flow under the skin may also affect the accuracy of oxygen level measurement. This may significantly vary from person to person. If your heart rate is high at 150 bpm or higher at rest, the measurement may become inaccurate or may fail. So, if you have worked out recently, it is important to rest for a while, until your heart rate goes down. These solutions should help in ensuring that your blood measurement will remain accurate and reliable.