More Pennsylvania districts will be mandating masks when schools open this fall amid rising COVID-19 cases.

Masks will be required for all Cheltenham staff and students, regardless of vaccination status, beginning Monday, Acting Superintendent Nancy Hacker said in an email to the community sent Monday night.

“While our COVID numbers are not as high as in other regions, we have seen a noted spike in the incidence and positivity rates, and a move from a ‘Moderate’ designation within our county to a ‘Substantial’ level of cases,” Hacker wrote. “Despite the increasingly grim statistics and news, we hope to once again greet our students with the hope and positivity that a new school year promises.”

» READ MORE: New Jersey to mandate masks for students and staff. Pennsylvania will leave the decision to districts.

The news came as Delaware Gov. John Carney on Tuesday morning announced universal masking for the start of the school year.

“There’s no higher priority than getting all Delaware children back in their classrooms full time this fall,” Carney said in a statement. “This consistent, statewide approach will help students, educators and staff return to school safely and without disruption.”

When students reported to a kindergarten readiness program in the Norristown Area School District Monday, everyone was masked: Superintendent Christopher Dormer announced last week the district would mandate face coverings.

“We see the wearing of masks as a key mitigation strategy to prevent the spread of COVID-19 within our schools, especially since the majority of our students are not eligible for the vaccine at this time, and due to the constraints with maximizing social distancing in fully reopened schools,” Dormer said in a video message to the Norristown community.

In Philadelphia, Superintendent William R. Hite Jr. has ordered all staff and students to wear masks in the 120,000-pupil system when classes begin Aug. 31.

Lower Merion schools announced last month that they would require masks, also.

“I know that many of us hoped that masks would no longer be needed in schools, but the rise in prevalence of the delta variant of COVID-19, and the fact that students under age 12 are unable to be vaccinated, make it advisable to return to masking as a mitigation effort in our schools,” Superintendent Robert Copeland wrote. “Having students masked will also limit the number of students who must quarantine and miss school, should they be identified as a close contact of an infected individual. Taking this step will enable us to continue as safely as possible toward our primary goal of offering in-person education going forward.”

Abington schools are also moving toward universal masking. The district’s revised COVID-19 health and safety guidance — to be discussed by the school board Tuesday night — states that “all students and staff are required to wear face masks indoors and on school transportation (unless medical conditions prohibit use), regardless of vaccination status,” according to board documents.

Though Gov. Tom Wolf has said he won’t require masks in schools but rather leave decisions up to individual school districts, Montgomery County’s Office of Public Health has recommended universal masking in schools for the upcoming school year.

In New Jersey, Gov. Phil Murphy has instituted a mask mandate for all schools in the state.

That stands in sharp contrast with David Damsker, Bucks County Health Director, who told The Inquirer in July that “schools should be in person, schools should not require masking, schools should get back to teaching kids.”

The Centers for Disease Control and Prevention has recommended schools operate fully in person, with masks for all students and staff.

Though the start of school is still weeks away, masking has been a hot-button issue for districts. In the Central Bucks School District, a township supervisor was cited for harassment after striking someone with a sign during a pro-masking news conference.