With COVID-19 cases rising, Philadelphia schools will require all students and staff to put their masks back on come Monday — and until further notice.

“As we’ve learned since the pandemic began, the coronavirus continues to evolve and so too will our response to it,” Superintendent William R. Hite Jr. said in an email sent to staff Friday afternoon. “As we work together to minimize the spread, please remember that our Health and Safety protocols are still in effect, including the importance of notifying the district if you test positive for COVID-19.”

The decision, which Hite said came at the recommendation of the city health department, affects students and staff in schools and on school buses.

The district’s move is “consistent with our ongoing guidance,” James Garrow, a Philadelphia Department of Public Health spokesperson, said in a statement, though the department made no specific recommendation that triggered the change. Currently, masks are recommended but not required indoors in Philadelphia.

“We applaud the school district’s efforts to ensure that everyone in their buildings and vehicles is being protected from COVID-19,” Garrow said. “As has been the case throughout the pandemic, businesses and institutions could be more proactive than the Health Department’s guidance, and this is an example of that.”

Monica Lewis, said that while the city’s current stance on indoor masking is strongly recommended, not required, district officials felt a return to mandatory masking was the right call.

“People take a mandate more seriously,” Lewis said. “We are in the home stretch. We want to make sure that our students can stay in school in person; this is an opportunity for us to have an extra layer of caution and safety for our students and staff and their families.”

Lewis said the district will continue to keep in touch with the health department and with experts at the Children’s Hospital of Philadelphia PolicyLab as the school year comes to a close.

The district’s decision comes as a handful of other suburban districts, including Cheltenham and Upper Dublin, are also requiring students to mask after months of mask-optional classes.

It was met with relief, in some quarters, and frustration in others.

“No air in most buildings, windows that open 6-8 inches at best. 90° weather coming. Can’t wait,” one district educator said on Twitter.

The educator said about 40% of students at their school were masking without a mandate.

Charlie McGeehan, a teacher at the Academy at Palumbo, was pleased with the decision.

“Never took mine off and neither did most of my students,” McGeehan said. “I think it’s the right move.”

Jerry Jordan, president of the Philadelphia Federation of Teachers, said he saw the need for masking.

“It is a shift that makes sense because we know that masking is one of the most effective mitigation strategies,” Jordan said in a statement. “We all want school buildings to remain open, and we want students and staff to be safe. This is one key measure of ensuring just that.”