Parisian authorities are facing legal action over the health threat from toxic lead particles released during the fire at the Notre-Dame Cathedral.
Hundreds of tonnes of lead within the cathedral's roof melted during the blaze in 2019.
It released toxic particles into the air, which settled in the local area.
A lawsuit accuses authorities of "gross negligence" for allowing people living in the city to be exposed to the harmful substance.
Lawyers for two local families, whose children were allegedly exposed to lead dust at their homes and schools, along with a health association and a trade union, say authorities endangered life by not reacting to the risk of lead poisoning.
"Despite the scale of the fire and knowledge about the risk of pollution and contamination... no precaution in particular was taken by the authorities involved for more than three months after the fire," their legal complaint says, according to AFP news agency.
A total of 400 tonnes of lead were reportedly dispersed over the French capital during the fire on 15 April 2019.
"Children (in creches and schools), neighbours and workers have clearly been exposed to the risk of lead exposure," the complaint reads.
"These facts amount to the crime of endangering the lives of others."
A simulation carried out in 2019 reportedly found particles had spread up to 50km (31 miles) from the cathedral.
The square in front of the cathedral, which is being rebuilt, was closed again to the public in May this year after tests revealed high concentrations of toxic lead particles.
Several months after the fire, city authorities ordered a deep-clean of schools in areas close to the cathedral, while children and pregnant women living nearby were urged to have blood tests.
The complaint says the city, run by Socialist Mayor Anne Hidalgo, withheld information from school directors and failed to act quickly enough. The mayor's office did not immediately respond to a request for comment.
It also targets the city's police department, the culture ministry and regional health authorities.
This is the second legal action against the authorities over lead levels.
French President Emmanuel Macron has vowed to rebuild the cathedral by 2024.
https://www.bbc.com/news/world-europe-57733690
