Spurred by the pandemic, New York City lawmakers have introduced new legislation that would reduce public school class sizes over the next three years, starting in fall 2022.

Parents and advocates have called for smaller classes for decades, citing research that shows shrinking classes leads to better test scores, higher college attendance rates, and other positive outcomes for students. But the bill introduced Thursday takes a different tack. Against the backdrop of the continued spread of COVID-19, it argues that smaller classes are a safety imperative.

“Class size is a public health issue,” said Council Member Mark Treyger, who co-sponsored the bill with Council Speaker Corey Johnson, at a press conference Thursday.

“It is time for the city to be forced to focus on the issue of overcrowded schools and classrooms,” said United Federation of Teachers President Michael Mulgrew.

If passed, the legislation would mandate a minimum of 35 square feet per student, up from the current ratio of 20 feet per student. Officials said that could shrink average classrooms down to 14 to 21 students, depending on the size of the room. Currently, high school classes are capped at 34 students, middle school classes at 30 students, and first-through-sixth-grade classes at 32 students.

But the legislation would not kick in this fall, when the issue of class sizes is especially urgent and could determine whether the city can pull off its plan to welcome all public school students back to buildings.

The Centers for Disease Control and Prevention has recommended three feet of social distancing within classrooms, although it has suggested flexibility, saying the priority is getting all students back to school in person.

Mulgrew said close to 200 schools are likely to have trouble fitting all their students at three feet apart. Mark Cannizzaro, the president of the Council of School Supervisors and Administrators, has said the number is much higher than that, estimating that more than half of the city’s 1,600 schools will have trouble accommodating all their students at three feet distancing.

Mulgrew said the union is waiting for the education department to provide a plan for how to make the social distancing guidelines work, including vetting additional spaces. “Everything should be on the table right now,” he said, adding that the union continues to expect and support a full reopening this fall. “We do want all of our children back,” he said.

Katie O'Hanlon, a spokesperson for the city's Department of Education, emailed a statement on Thursday evening that said school officials will review the legislation.

"We follow a gold-standard approach approved by health experts and class sizes are capped to ensure every student gets the individual attention and space they need. We’re making historic investments to hire more teachers, build new instructional space and support smaller class sizes," she said.

Leonie Haimson, executive director of the advocacy group Class Size Matters, said it’s unfortunate the legislation could not kick in this fall, but she said it could make a difference going forward. “I’m really excited about it,” she said. “Despite the crying need for smaller classes, we’ve made so little progress. With COVID, smaller classes are more critical than ever.”

Haimson and other advocates had hoped the city would use increased state and federal funding to invest substantially in reducing class sizes, but the budget passed last month only included a pilot project with smaller classes at 72 overcrowded elementary schools.

This article was updated on 7/29/21 at 9:35 p.m. to include a statement from the Department of Education.