New York City teachers are heading back into the classrooms today, but not everywhere, with more than 15 different schools still needing repairs across the city.

The Department of Education tells News 12 P.S. 45 in Bushwick, which is actually in two different buildings, is among 10 school buildings that are in need of ventilation repairs.

The DOE says while it hopes to have the repairs done by the Sept. 21 reopening date, they’re also working to find alternative learning locations just in case.

Since June 3, the DOE says it has been working hard trying to ensure every school building is safe and ready to open. It says it has been surveying, assessing and repairing school buildings across the city.

One of its focuses has been on ventilation and ensuring there’s a free flow of fresh air. News 12 is told Ventilation Action Teams, which are made up of third-party engineers, are going through and assessing more than 1,400 buildings.

United Federation of Teachers President Michael Mulgrew said in a statement, “Keeping everyone safe is our top priority. Inspections by the DOE and the UFT identified these serious ventilation issues, and we will continue to monitor these buildings and other schools to make sure all ventilation problems are solved.”

The UFT adds repairs and upgrades cannot be made and that they will work with the DOE to help find alternative space before students return on Sept. 21.