The city Department of Education said Tuesday the new timetable was the result of mediation between the city and New York Communities for Change. The group had filed a lawsuit in 2011 demanding the city move faster to remove lighting tainted by PCBs.
PCBs are suspected of causing cancer and other diseases.
City officials say nearly 800 of 1,400 school buildings could have PCB-containing light fixtures. They agreed in 2011 to remove the lights within 10 years, saying the timetable would allow them to more easily absorb the cost.
The agreement was hashed out between New York Lawyers for the Public Interest and city attorneys.