The Philadelphia School District this week sent layoff notices to 53 teacher assistants and other aides, raising the ire of their union.

Thirteen are nonteaching assistants who help maintain order in hallways among other tasks, and 40 are teacher assistants with varying jobs.

"These were due to budget decisions at the school level," district spokeswoman Barbara Farley said yesterday.

In Philadelphia, principals are allotted budgets and have some leeway in how to spend the money.

Farley said the layoffs were not part of the district's effort to erase the remaining $20 million deficit in its $2.18 billion budget.

District enrollment is expected to dip by about 8,000 this school year, but Farley could not say how many of the layoffs were due to fewer children and how many to schools' deciding "they wanted to use their money differently." Some schools may have found other ways to deal with the tasks performed by the assistants, she said.

District officials, who expect to start school Sept. 10 with about 166,000 students, also had no information yesterday on how many schools the layoffs affected or how much money they would save.

The layoffs raised the total for assistants and aides this summer to 129, district officials said.

Jerry Jordan, president of the Philadelphia Federation of Teachers, said the layoffs would mean fewer adults in schools and more chances for disruption.

"With the loss of the NTAs, we're ripe for some very, very serious problems in the area of school safety," Jordan said. "These are the people who help to inform school personnel that there's going to be a fight after school or there's going to be a problem in the lunchroom."

The union also expressed concerns this week about teacher vacancies.

"The way you open your building, that sets a tone," Jordan said. "With the lack of the appropriate number of teachers and the elimination of support staff, we've got some real concerns."

As of yesterday, the district had 121 vacancies, down from 134 last year, said Shawn Crowder, senior vice president of human resources.

Special education, math and science are among the areas short of teachers, she said.

The district expects to start school with about 60 vacancies, Crowder said. Last school year opened with 43.

The human-resources office will work through the week, including tomorrow, to get as many new teachers as possible ready for the classroom, she said.

Contact staff writer Susan Snyder at 215-854-4693 or ssnyder@phillynews.com.