A new system was launched for California residents with smartphones to notify them of potential COVID-19 exposures. 

The app, known as CA Notify, uses Bluetooth technology to notify users if someone they were recently in contact with has tested positive for the coronavirus. The person who tested positive must also have the app in order for anyone they come in contact with to receive the notification. If that person tests positive, anyone they have come in contact with will be notified. Apple and Google smartphone users can choose whether or not to opt into this notification system. 

The app utilizes the phone’s short range Bluetooth radios to detect when two phones were near each other for a period of time over 15 minutes. 

This notification system started from a pilot program which took place during the fall with students and staff from University of California, San Francisco and University of California, San Diego. 

In order to set up this new notification system, iPhone users must go to their settings, scroll down to exposure notifications and turn them on, selecting the United States for the country and California for the state. The availability of this app extends to Android, which can be downloaded via the Google Play Store. 

“This holds a lot of promise,” Gov. Gavin Newsom said at a news conference on Monday, Dec. 7. “The more people that participate in it, the more that opt in, the more effective this program can be.”