SACRAMENTO, Calif. (AP) — California is rolling out a voluntary smartphone tool to alert people if they spent time near someone who tests positive for the coronavirus as cases and hospitalizations soar throughout the state.

Gov. Gavin Newsom announced the tool on Monday and said people can opt in to use it starting on Thursday.

Officials say the tool doesn't track people's identities or locations but uses Bluetooth wireless signals to detect when two phones are within 6 feet of each other for at least 15 minutes.

Starting Dec. 10, Californians can enable CA Notify in their iPhone settings or on Android phones by downloading the CA notify app from the Google Play Store.

The encounters are temporarily logged in a way that doesn’t reveal a person’s identity or geographic location.

If people who have activated the technology test positive for the virus, they get a verification code from the California Department of Public Health and can use that to send an anonymous alert to other participating phone users they might have exposed over the past 14 days.

Sixteen other states, plus Guam and Washington, D.C., have already made available the system co-created by Apple and Google, though most residents of those places aren’t using it. The tool has been used on a pilot basis on University of California campuses.

Click here to add your phone to California’s exposure notification system to get COVID-19 exposure alerts and to protect those around you.