"The relevant authorities, including the diocese...neglected to assist residents, visitors and workers, allowing them to be exposed to the toxic fallout," Robin des Bois said in its lawsuit filed on 26 July 2019.
Robin Hood, its English name, accuses health agencies, government officials and the city of Paris of "deliberately putting people in danger" by not immediately taking measures to limit exposure to the contamination.
Authorities insisted last week that there was no danger posed by contamination, after a media report alleged they had covered up lead pollution levels in local schools.
Better to be safe
However, city officials on Thursday shut two schools near the Gothic cathedral after tests revealed high levels of lead pollution on a playground they shared.
Work at Notre-Dame was also halted after Prefect Michel Cadot, the top government official in the Paris region acknowledged that anti-contamination measures were insufficient.
Hundreds of tonnes of lead in the church's roof and steeple melted during the blaze, releasing toxic particles.
Cadot said the square in front of the cathedral, usually bustling with thousands of tourists and pilgrims, would be cleaned with a high-powered system that had been tested on a small area close to church.
Lead pollution can cause neurological defects in humans, especially children, as well as nervous system and kidney problems.