The Los Angeles Unified School District Board of Education on Tuesday voted to ban smartphones for its 429,000 students in an attempt to insulate kids from distractions and social media that undermine learning and hurt mental health.

The board of the second-largest U.S. school district voted 5-2, approving a resolution to develop within 120 days a policy prohibiting student use of cellphones and social media platforms. The policy would be in place by January 2025.

“I think we’re going to be on the vanguard here, and students and this entire city and country are going to benefit as a result,” said board member Nick Melvoin, who proposed the resolution.

On Monday, U.S. Surgeon General Vivek Murthy called for a warning label on social media platforms, akin to those on cigarette packages, citing what he considers a mental health emergency.

L.A. schools officials will consider whether phones should be stored in pouches or lockers during school hours and what exceptions should be made for students of different ages and pupils with learning or physical disabilities.

School officials will also examine using technology to restrict social media platforms and how the policy will address different types of devices such as smart watches.

Board member George McKenna voted against the resolution based on his concerns the policy would be too restrictive. Board member Scott Schmerelson also cast a “no” vote, saying it was unclear whether the ban would be during non-instructional time and who would enforce the policy.

“I think it’s going to be a full-time job being the police of the phone,” Schmerelson said.

Los Angeles joins a number of smaller school districts to ban access to phones or social media. Florida, with some 2.8 million public school students, last year passed a law requiring school districts to prevent student access to social media. Several other states have introduced similar legislation.

While the research on mental health risks remains incomplete, Murthy, the surgeon general, said the emergency was so apparent as to demand action.

Murthy cited a study in the medical journal JAMA showing adolescents who spend more than three hours a day on social media may be at heightened risk of mental illness, while referring to a Gallup poll showing the average teen spends 4.8 hours per day on social media.

The L.A. school district cited other evidence that cellphone addiction was linked to soaring rates of anxiety and cyberbullying.

—Daniel Trotta and Brendan O’Brien, Reuters