The Apple Watch spO2 sensor and outliers in healthy users

NPJ Digit Med. 2023 Apr 8;6(1):63. doi: 10.1038/s41746-023-00814-x.

Abstract

It is unclear how frequently the Apple Watch produces spO2 measurements outside of the normal range in healthy individuals at rest. We conducted a head-to-head comparison in 38 healthy individuals between two watches and two medical-grade pulse oximeters. Fourteen percent of watch measurements yielded spO2 values below 95%, with no values below 92%. Results suggest that outliers measured by the watch should not be a cause for concern in otherwise healthy individuals.