It’s unclear exactly how many school gymnasium floors in New Jersey have the potential to emit toxic mercury vapor over time, or are already doing so.

But the state can be sure of one thing now: no future Schools Development Authority projects will include floors that contain a mercury catalyst, which can lead to harmful effects on humans and has already been recognized in several New Jersey instances.

The SDA, which funds and manages construction and renovation of schools in 31 New Jersey districts, announced it will be requiring an additional certification from manufacturers of rubberized and/or urethane floors that can guarantee the product is free of any mercury catalyst during manufacturing and installation.