A year-long effort to eliminate chemical fumes in the basement of an elementary school near the Gowanus Canal has been unsuccessful, raising the likelihood that students will return to class after the summer with state officials still pursuing a permanent fix.

The New York State Department of Environmental Conservation and New York State Department of Health sent parents and staff at Brooklyn's P.S. 372 an update on the contamination on Juneteenth, at the beginning of a three-day weekend. State officials wrote that while they have successfully prevented fumes from entering the annex building from below, they have discovered additional contamination, possibly from above ground.

That means state officials will have to conduct further testing in the basement of the Carroll Street school’s annex building and will have to do additional mitigation efforts that could last through the next school year.

“When the PTA sent this parent letter out, it was a holiday. No one’s going to be looking at their emails,” said Julia Finegan, a school parent concerned about the annex building’s air quality. “If they did read it, they're, like, ‘What is this? What's happening?’”

The ongoing attempts to address the contamination highlight the challenge of moving on from Gowanus’ industrial past. New high-rise apartment buildings are rising along the notoriously toxic canal in the midst of a Superfund cleanup.

The letter detailed the latest sampling results from the school, which show an annex building remains contaminated with mainly petroleum-based chemicals, including benzene, a known human carcinogen. The agencies maintain the contamination is only slightly above normal levels and poses no risk to human health or need for students and staff to relocate.

Officials do not know the cause of the contamination, but believe it’s “likely from an unknown above-ground source,” according to the letter signed by DEC project manager Aaron Fischer and state Health Department official Daniel Tucholski.

That theory marks a shift. When the fumes at P.S. 372 were first detected in 2024, state officials suspected they were coming from a leaky petroleum tank buried under the building or from contamination at a nearby site in the midst of a cleanup.

The discovery was the result of a state initiative to test the air quality in basements around the neighborhood following the detection of contaminated air in the basement of the Royal Palms Shuffleboard Club. The club owners have said that a remediation system has been effective and the air is safe to breathe.

Environmental officials installed a similar system at the school. The sub-slab depressurization system sucks contaminated air out of the annex building’s basement like a straw. Nearly two years later, that mitigation system “seems to be doing what it's supposed to do,” said Lenny Siegel, the executive director of the Center for Public Environmental Oversight who reviewed the latest [2025] sampling results. The group promotes public participation in environmental cleanups.

“It looks to me like the DEC’s doing what any standard response would be,” Siegel said. “I would say they're doing a good job.”

While the DEC said the mitigation system is working as designed, the agency acknowledged that fumes can still enter the decades-old annex building through sections of the basement walls.

The agency wrote it is working with the New York State Department of Health to develop a plan to further reduce those fumes, which may include the installation of an additional ventilation system. Officials said they were waiting on the results of additional samples taken last month. State investigators said they will continue to monitor the contamination.

"Both agencies are taking necessary steps to ensure that any potential exposure concerns are accurately addressed to prevent potential impacts to the school’s students, faculty, staff, and the surrounding environment," Fischer wrote in a statement.

Environmental and health officials met with the school’s principal, representatives with the city’s Department of Education, the building’s owner – the annex is leased to the school by the church next door – and a representative from the United Federation of Teachers Safety and Health Department in May and June.

Finegan criticized officials for not being more forthcoming with information.

“Once everything was installed, they were like, ‘Oh, it's fine, everything's installed, it's ready to go,’ which we now know was not necessarily true,” she said.

To address staff concerns, the city teachers union is conducting a confidential, voluntary health survey in September.

Surveys will be shared with experts from Northwell Health who will analyze the information and share their review with union members and the city’s health department.

“The UFT will continue to monitor the work the state is doing at P.S. 372 and keep the staff and school community updated,” Alison Gendar, a spokesperson for the teacher’s union, wrote in an email.

In May, the union opened a UFT Teacher Center in the annex building to host professional development programs.