LEWISTON — Students and staff returning to school Sept. 1 will be required to wear masks while indoors.

In a close, late-night vote Thursday, the School Committee approved the superintendent’s recommendation to require masking in district buildings.

The committee voted 5-4 in favor of Superintendent Jake Langlais’ recommendation after a five-hour meeting during which dozens of parents, teachers and residents spoke on the pros and cons of masking.

Langlais noted the risks and benefits of his recommendation in a presentation to the committee.

“Those opposed may struggle with compliance,” he said. But “when transmission is moderate or higher, masks act as a barrier. Those with compromised situations may have reduced anxiety. We demonstrate that we care for others and even when it’s hard, we do what we can.”

Community transmission rates, set by the state, include low, moderate, substantial and high. Lewiston’s rate changed from moderate to substantial during the School Committee meeting Thursday night, just before the committee voted.

Members first voted down a motion by Janet Beaudoin to adopt a “family choice” model that would make masks optional. That vote was 5-4, with Beaudoin, Chairwoman Megan Parks and Tanya Whitlow and Ron Potvin voting in favor.

Kiernan Majerus-Collins then made a motion to adopt Langlais’ recommendation.

Paul Beauparlant, Majerus-Collins, Luke Jensen, Lynnea Hawkins and Vice Chairman Bruce Damon — those who voted against optional masking — voted in favor of the masking mandate.

Langlais said Friday that he was happy that the committee made sure every voice could be heard.

“Once every voice that wanted to be heard could be heard, (the committee) put forth what I think was a responsible motion in a really difficult climate,” he said.

Both motions were responsible, he said, “and it is important that we have the agility we need if conditions or information changes.”

He added, “I do think we landed in the right place.”

Because the community transmission rate changed to substantial Thursday, either motion would have resulted in masking. Beaudoin’s motion gave Langlais the authority to mandate masking if the rate was substantial or high.

Chairwoman Parks said Friday that she had hoped the committee could be more flexible about masking and require it under only the two highest transmission categories.

“But I trust (Langlais) will make the appropriate adjustments as things progress,” she said. “Most importantly, our students will be able to return to school five days a week safely.”

Majerus-Collins said Friday that he was grateful to those who came out to speak in support of public health, and to his colleagues who voted for safety in the city’s schools.

“By requiring universal indoor masking, we have taken an important step toward keeping our students and teachers safe and in school full time,” he said.

The committee Thursday also voted unanimously to offer pooled testing of students and staff for COVID-19.

For students, participation in the testing requires parental consent. The process involves a “self-swab” using short, noninvasive swabs.