https://wccftech.com/apple-watch-blood-oxygen-detection-ios-14/

The Apple Watch could obtain the ability to detect blood oxygen levels for the first time, after 9to5Mac learned according to a leaked iOS 14 code snippet. According to more information, blood oxygen levels that are between 95 and 100 percent are considered healthy, while anything below 80 percent can result in degraded heart and brain functionality.

Unfortunately, though the leaked iOS 14 code reveals that a new feature could be arriving, it’s not confirmed if older hardware will support it. That can mean if we’re lucky, models like the Apple Watch Series 4, Series 5 and older generations will get support for it. If not, then users that want to take advantage of this feature will have to wait for the upcoming Apple Watch Series 6, which is reportedly due later this year and that will spending more money to experience the latest and greatest features.