Is the Apple Watch Series 6’s Pulse Oximeter Sensor Mostly Useless?

Apple Watch Series 6 in Apple Store Credit: Jack Skeens / Shutterstock
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Apple’s most exciting new feature in its Apple Watch Series 6 is also its most controversial. Though Apple heaped praise for the pulse oximeter sensor, reviewers and early adopters of the device may be singing a different tune.

According to a scathing report from the Washington Post, the pulse oximeter in the Apple Watch is mostly useless.

As ZDNet journalist David Gerwitz points out, a drug store pulse oximeter is better than the Apple Watch Series 6 in more than one way. It has batteries that can last far longer and can read a blood oxygen levels quickly and more accurately.

Its accuracy is directly correlated to its design. Traditional pulse oximeters measure your blood oxygen at your fingertips which are filled with blood-carrying capillaries. This abundance of blood at your fingertips intensifies the signal the blood oxygen sensor is trying to read. It’s like turning the volume up to 12 on your radio.

Your fingers are also thin enough to allow light to shine through them, further improving the sensor’s ability to measure blood oxygen levels.

The Apple Watch Series 6, on the other hand, measures blood oxygen levels on your wrist, which has fewer capillaries than your finger.

It also must use reflected light to measure blood oxygen because light cannot penetrate through your wrist. These obstacles limit the effectiveness of this wrist-based sensor, which certainly matches the experience of the Washtington Post’s Geoffry Fowler.

Fowler complained that the Apple Watch was inconsistent. It sometimes would read a very healthy 100 percent saturation. While the other recordings put him into the emphysema level.

Apple touted its pulse oximeter during its September press event, but the claim that it is a valuable health measurement may be slightly overstated.

Apple Vice President for Health Sumbul Ahmad Desai kicked off this health presentation by stating that the blood oxygen sensor in the Apple Watch brings “another valuable health measurement to users.” She then noted how blood oxygen and pulse oximetry “are terms that we’ve heard a lot about during the COVID pandemic.”

Apple’s executive team may be alone in promoting the Watch’s blood oxygen sensor as a viable health tool. The company’s website is playing down the sensor’s utility, noting that the blood oxygen app is “not intended for medical use.” The company added that the Apple Watch Series 6 sensor is “only designed for general fitness and wellness purposes.”

Anecdotally, Apple did not submit the sensor to the FDA for testing, so it is not FDA approved for medical use.

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