Google is adding heart and respiratory rate monitors to the Fit app on Pixel phones this month, and it plans to add them to other Android phones in the future. Both features rely on the smartphone camera: it measures respiratory rate by monitoring the rise and fall of a user’s chest, and heart rate by tracking color change as blood moves through the fingertip.

The features are only intended to let users track overall wellness and cannot evaluate or diagnose medical conditions, the company said.

To measure respiratory rate (the number of breaths someone takes per minute) using the app, users point the phone’s front-facing camera at their head and chest. To measure heart rate, they place their finger over the rear-facing camera.

Image: Google

A doctor counts a patient’s respiratory rate by watching their chest rise and fall, and the Google feature mimics that procedure, said Jack Po, a product manager at Google Health, in a press briefing. “The machine learning technique that we leverage basically tries to emulate that,” he said.

Google’s heart rate monitor is similar to a feature that Samsung included on a number of older model Galaxy smartphones, including the Galaxy S10. The company removed the feature for the S10E, S20, and later phones.

Heart rate data from Google’s app will be less comprehensive than the types of readings someone could get from a wearable device, which can continuously monitor something like heart rate as someone goes through their daily life. But an at-home feature that can check in on these metrics on demand is still a useful tool, Po said in the briefing. Anything that increases the number of measurements someone has of their heart or breathing rate is important — doctors, for example, usually only get a measurement at most every few months as someone comes into an office, he said.

“If users were to take their heart rate once a week, they would actually get a lot of value,” Po said. “They’ll get a lot of value in tracking whether their heart rate might be improving, if exercise is paying off.”

GIF: Google

Google chose to incorporate these functions into the smartphone in order to make it accessible to the widest number of people, Po said. “A lot of people, especially in disadvantaged economic classes right now, don’t have things like wearables, but would still really benefit from the ability to be able to track their breathing rate, heart rate, et cetera.”

Internal studies on Pixel phones showed that the respiratory rate feature was accurate within one breath per minute both for people with and without health conditions, said Jiening Zhan, a technical lead at Google Health, during the press briefing. The heart rate feature was accurate within 2 percent. That feature was tested on people with a range of skin tones, and it had a similar accuracy for light and dark skin, she said. The team plans to publish a scientific paper with the data from its evaluations.

The team will study how well the features work on other phones before making them available outside of the Pixel. “We want to make sure that you know, the rigorous testing is done before it’s released to other devices,” Zhan said.

Right now, the features are described as tools that can be used for general wellness. Google isn’t claiming that they can perform a medical function — which is why it doesn’t need clearance from the Food and Drug Administration (FDA) to add them to the app.

Eventually, they might take the app down that road, Po indicated. The tests done on the features show that they’re consistent with clinical products, he said, so it’s a possibility in the future. “Frankly, we haven’t done enough testing and validation to say that it can definitely work for those use cases yet, but it’s definitely something we’re exploring,” Po said.