Buzz
There’s a common belief that you can use your smartphone to accurately check your SpO2 levels—that is, your blood oxygen saturation. While it would certainly be convenient to quickly access that data, just like when your doctor uses a small clamp to measure it during a checkup, I regret to inform you that the number displayed on your smartphone is probably not correct.
If you're using an app, or even a built-in feature on your phone, to measure your blood oxygen levels, you're just wasting your time. Just to clarify: this is different from using a pulse oximeter that connects to your phone to deliver the data. In that case, it’s the oximeter—a specialized device designed for this purpose—that's doing the real work, not your phone’s “health sensor.”
But don’t just take my word for it: As reported by Android Central, even Oxford University is chiming in on the debunking. A recent post from its Centre for Evidence-Based Medicine states:
“There is no proof that any smartphone technology is reliable for measuring blood oxygen saturation. Moreover, the scientific foundation of such technologies is questionable. Therefore, oxygen saturation readings from these technologies should not be trusted.”
Researchers evaluated both an app—which has since been removed from the App Store, which is a positive—and Samsung's claims that its smartphones' red light emitting diode can somehow detect your “stress,” which is supposedly related to your “oxygen saturation levels.” Oxford University researchers strongly disagree, stating, “Oxygen saturation levels cannot be measured using a smartphone assessment of stress.”
What about other devices that supposedly measure your blood oxygen levels? For instance, your newer FitBit can give you a reading, but even the company mentions in the fine print that you shouldn’t rely on the number as absolute:
“Unless otherwise specified, Fitbit products and services are not medical devices and are not intended to diagnose, treat, cure, or prevent any disease. Regarding accuracy, Fitbit has developed products and services to track certain wellness information as accurately as reasonably possible. However, the accuracy of Fitbit’s products and services is not meant to be on par with medical or scientific measurement devices.”
Why is everyone discussing oximeters right now?
It’s straightforward. Understanding your blood-oxygen levels can help you figure out whether the symptoms you're dealing with might point to a COVID-19 infection. However, I hesitate to make this claim too strongly, as blood-oxygen level is just one data point—and not even the most crucial one. As Dr. Albert Rizzo, the chief medical officer of the American Lung Association, recently stated to Wirecutter:
“Most people don’t need a pulse oximeter,” he said. “A drop in oxygen level in someone with COVID-19 is one of the factors to consider when deciding whether to seek more care than simply staying at home [...] monitoring symptoms—such as cough, shortness of breath, and chest discomfort—are the key things to focus on.”
As Ada Stewart, MD, FAAFP, recently told us, it’s crucial to know how to use a pulse oximeter properly, as it directly impacts the accuracy of the readings. As we previously noted:
“...if a patient doesn’t understand how to properly use a pulse oximeter, trying to use it can cause unnecessary stress in an already frightening situation. For example, even a bit of nail polish on your fingernail can lead to a falsely low reading.”
While it’s useful to have a basic understanding of your blood-oxygen levels if you have legitimate concerns about COVID-19, using an inaccurate device doesn’t offer much benefit. You could end up causing yourself unnecessary panic when your reading drops by five percent over the course of a day, unaware that it may be well within the normal margin of error for the device.
I haven't come across any studies directly comparing the accuracy of your Fitbit’s blood-oxygen reading to something you’d get at a doctor’s office, so take those results with a big grain of salt. Pulse oximeters that are FDA-cleared must meet an accuracy standard of ±3 percent. The oximeters found in various smart devices generally rely on a different technology for their readings compared to what you’d find in a fingertip device, and that technology is typically less accurate.
I can’t say if you really need a reliable way to measure your blood-oxygen levels at home, but if you think you do, be aware that the quick, easy, and affordable solutions may not give you the accuracy you’re looking for. Worse still, using that number to self-diagnose COVID-19 at home could harm your mental health more than it helps your physical health. If you feel it’s necessary to regularly measure your blood-oxygen levels, consult your doctor. Better yet, ask if they have recommendations for a more accurate device.
More on portable oxygen concentrators from G/O Media’s partner.
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