As the reviews of Apple’s latest smart watch were published last week, much was made of its new star feature — something that less than a year ago few of us could have imagined caring about: a blood oxygen sensor.
In conjunction with an app, the Apple Watch Series 6’s oxygen monitor measures the oxygen saturation (SpO2) in users’ blood. Low blood oxygen can be an effect of Covid-19, and doctors have used SpO2 levels to determine the severity of patients’ conditions.
It’s the latest addition to an ever-expanding list of health data we can track, from sleep to fertility, handwashing and noise exposure. But do we really need it all? Evidence suggests that health trackers don’t necessarily make people healthier. Lionel Tarassenko, a professor
