PARIS — A French environmental group has filed suit over what it says was the government’s delayed response to the large-scale release of lead into the atmosphere during the Notre-Dame fire.

Over 400 tons of lead in the spire and the cathedral’s roof burned- the night of the April 15 fire, releasing toxic particles into the air, according to the environmental group, the Robin Hood association. The release endangered spectators of the fire, cleanup workers, apartment dwellers and even the schools in Notre-Dame’s neighborhood, the group said in its lawsuit.

[Read about the enormous risks that firefighters took to prevent the collapse of Notre-Dame.]

The case accuses the French authorities of minimizing the problem at first, though they now appear to be making up for lost time.

At least three schools have been closed, the group says, and cleanup and consolidation work at the cathedral has been stopped because of the danger of ingesting lead particles, which can cause neurological defects.