North Stonington — The start of the academic year was abruptly postponed for students at North Stonington Elementary School, after air testing for hazardous materials led to three rooms in the building being closed and left administrators little time to reorganize the facility.

The school, where classes were supposed to start on Wednesday, will remain closed until Tuesday, Sept. 5, Principal Veronica Wilkison said.

Superintendent of Schools Peter Nero informed staff and parents in emails and voicemail messages Tuesday afternoon, after discussing the air test results with representatives from the Environmental Protection Agency office in Boston.

The testing was the latest development in a yearslong effort by the district to monitor the schools for the presence of polychlorinated biphenyls, or PCBs.

PCBs are viscous liquids valued for their flame-resistant stability that were used in window caulking, some paints and other building materials. In 1979, the EPA banned the materials from new construction, as the agency considers the chemicals probable carcinogens, and set exposure guidelines for their consumption and inhalation.

The state Department of Energy and Environmental Protection and the EPA have been working with the district on additional testing to determine the extent of PCB contamination in the school.

The most recent round of testing was conducted in the month of August, and sampled a number of locations in the building for dust and air composition.

Higher-than-recommended levels of PCBs were found in three rooms: the music room, the school's library and a room that housed the school's math interventionists and speech language pathologist.

Concentrations of PCBs in those rooms were high in both "air and surface samples" wrote Emily Bender, a public affairs specialist at the EPA, in an email Wednesday.

Nero said that the levels were higher than the EPA exposure guidelines for elementary school-age children. The levels did not exceed the guidelines for adults.

The wipe tests, which assess whether dust in the school contains high concentrations of PCBs, came back clear, Nero said. But the area carpets in the classrooms needed to be removed and disposed, as well as some carpet tiles in one small area in the entrance to the school.

The results of testing conducted by Eagle Environmental LLC still were being finalized on Wednesday.

The district has long known about the existence of PCBs in school buildings. PCBs could be in as many as two-thirds of Connecticut public schools, according to an analysis by WNPR. Renovations of both the elementary school and Wheeler Middle/High School include money to completely remediate the potentially toxic chemicals.

"I've been here for six years and I said we need to get this done from the beginning," Nero said.

Once the school made the decision to close the three rooms, Wilkison said district officials quickly worked to develop a plan to move instruction out of the closed rooms, but realized that there was too much work to get the school ready in time for Wednesday, the original first day of school.

The district has long sought temporary solutions for the hazardous materials, with the expectation that eventually a building project would be funded that would solve the problem.

Since the first building project was proposed in 2014, Nero said he has been informing both DEEP and the EPA that a school building project would resolve their concerns about PCBs. The current plan is to move the elementary school students out of the building in December 2018 so the building can be renovated and PCBs removed.

However, the state budget impasse has complicated things: Since the state legislature hasn't yet passed a bonding package that includes money for school construction, the town's project has been delayed into the fall.

"If the state had a budget, we would have broken ground in July," Nero said.

Crews will be working to encapsulate some of the sources of PCBs in the three affected rooms, but the rooms will be closed for the time being, Nero said.

On Wednesday, the school had hired a company to vacuum dust from books in the school's library and move them out of the room. Staff members moved the books upstairs into a special education office, which will be used as a temporary library, Wilkison said.

There was briefly concern that the books couldn't be used because the bookshelves in the library can't be moved, but Wilkison put out a call Wednesday morning to teachers to donate bookshelves for the makeshift library, and many teachers came in to donate theirs, she said, thanking the "amazing staff" for their generosity.

Music instruction may be brought into classrooms rather than having a dedicated music room, Nero said.

The math interventionists and speech language pathologist will be moved separately to other spaces in the building.

Unlike the original first day of school, the new first day on Tuesday, Sept. 5, will be a full day of classes.

"The most important thing is kids and staff are safe," Wilkison said. "We're still going to have a great first day and a great year."

The school board will hold a special meeting with the superintendent at 7 p.m. Thursday, Aug. 31, in the elementary school's multipurpose room to discuss the results of the testing, what steps the district is taking and address any concerns that parents might have, Carlson said. Representatives from Eagle Environmental also will be present.

n.lynch@theday.com