The New York City Department of Education is informing parents of its plan to clean up PCBs.
Schools identified as having PCBs have sent home letters detailing the work, which it says will take place outside of school hours.
Schools built in the 1950s and early '60s are being worked on first because lighting fixtures there are more likely to leak the toxic chemicals.
Buildings with at least one elementary school will also take priority over secondary schools.
It will take about a decade to remove PCBs from the approximately 700 affected schools.
Some have criticized the plan, saying it takes too long and puts the health of students and teachers at risk.