Class Action Suit Claims Apple Watch Is Terrible at Monitoring Blood Oxygen on Dark Skin

The most-commonly used blood sensing pulse oximeters routinely fail at accurately registering blood oxygen levels for people with Black and brown skin.

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A line of Apple Watches on display, some showing the front and some showing backs.
The latest Apple Watches have included blood oxygen sensors using green, red, and infrared LEDs, though researchers have noted for decades that such sensors routinely fail at accurately gauging blood oxygen on darker skin.
Photo: Feline Lim (Getty Images)

A new class action lawsuit claims the Apple Watch’s blood oxygen sensor isn’t formatted to take darker skin tones into account, which is only exacerbating the noted biases of blood sensing tech that has routinely failed to accurately gauge blood oxygen levels for Black and brown people.

The suit was filed Dec. 24 in Manhattan federal court on behalf of Alex Morales, a New York resident who bought an Apple Watch between 2020 and 2021, according to court documents. Apple has 21 days to respond to an initial summons.

Pulse oximeters have existed since the 1970s and use light to register oxygen saturation. You’ll probably recognize the fingertip pulse oximeters that look like a paper clamp attached to the end of a finger, but phones and smart watches also make use of simpler, light-based oximeters. But even since their inception, the inherent bias shown by pulse oximeters on darker skin tones has become a noted issue in the medical community. A Stat article from this past August noted researchers are trying to develop oxygen readers that actually consistently work on darker skin tones.

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The “revolutionary” Blood Oxygen feature has been a staple on the Apple Watches since the Series 6. The company claims it compensates for “natural variations in the skin” with its four clusters of LED lights on the back of the watch. Apple’s Blood Oxygen app page mentions measurements “are not intended for medical use and are only designed for general fitness and wellness purposes.” Although the lawsuit doesn’t explicitly say Morales or other users utilize Apple Watches to gauge accurate medical data, it instead proposes that Apple has failed “to recognize the failings of pulse oximetry in general with respect to persons of color.” The lawsuit mentions that researchers have “confirmed the clinical significance of racial bias of pulse oximetry using records of patients taken during and before the pandemic.”

Gizmodo reached out to Apple for comment but we did not immediately hear back.

Multiple studies made it clear that minorities and other marginalized groups had been hurt worse during the worst months of the covid pandemic. A letter published in The New England Journal of Medicine noted two years ago this month that devices meant to monitor blood oxygen levels using pulse oximetry were routinely failing to accurately gauge when Black patients entered a state of hypoxemia, AKA when blood oxygen is below normal levels.

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“The ‘real world significance’ of this bias lay unaddressed until the middle of the Coronavirus pandemic, which converged with a greater awareness of structural racism which exists in many aspects of society,” the lawsuit states.

As AppleInsider noted, users previously complained back in 2015 that dark tattoos messed with the device’s sensors. The Apple Blood Oxygen app page notes that tattoos can block light from the sensor, though it makes no mention of skin color.

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Although the lawsuit does not give any concrete example of any user getting inaccurate results from Apple’s blood sensor. Gizmodo reached out to the New York law firm Sheehan & Associates for additional comment, and we will update this story if we hear back. The lawsuit also references a study published in the Digital Health open access journal that claimed Apple’s oxygen sensor was on par with most medical-grade oximetry devices, but the suit claims the study “fails to recognize the failings of pulse oximetry in general with respect to persons of color.”

Apple is likely used to such class action suits for its wide suite of products, but this latest in a long line of user deceit claims shows what happens when companies cram “everything” devices full to the brim with technology, even tech that has proved racially biased. You don’t have to look far either, as only recently have companies like Google explicitly marketed their Pixel cameras ability to capture dark skin accurately. Apple has said it worked on its AI to improve dark skin tone rendering, though some users have noted issues even with the latest iPhone 14 and on iOS 16.

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Though the suit still needs to obtain class certification, it’s welcoming claimants from New York as well as North Dakota, Wyoming, Idaho, Alaska, Iowa, Mississippi, Arkansas, North Carolina, and Utah.