French President Emmanuel Macron may have vowed to rebuild Paris’ Notre-Dame Cathedral in just five years but it seems his plans have already been hit by delays and the threat of litigation.

Exceptionally high levels of lead recorded in the air after a fire ravaged the cathedral in April this year have put a halt to restoration works. The devastating fire tore through the national treasure while it was undergoing a restoration programme causing the cathedral’s iconic spire to collapse. The blaze also melted hundreds of tons metal from the cathedral’s roof and steeple, sending toxic lead particles into the air across the local neighbourhood and stoking fears of a health crisis.

The Robin des Bois (Robin Hood) group of environmental protectionists are now suing Parisian authorities for “deliberately putting people in danger” by failing to take immediate remedial action to contain this toxic fallout.

Paris officials insisted for weeks following the fire that the lead levels did not pose a risk to human health. It was considered sufficient for locals to clean surfaces with a damp cloth and for children and pregnant women to wash their hands frequently. A police statement advised that high lead levels were limited to the immediate area surrounding the cathedral, which is inaccessible to the public. It also read that there was no risk of toxic inhalation from the air.

However, in July, new safety measures were introduced, which suggest otherwise.

Officials ordered a deep clean of schools near Notre-Dame to remove possible toxic dust from the walls, furniture and playgrounds. Health authorities advised that pregnant women and children should have blood tests. A school holiday program run in the vicinity of the cathedral site was shut down after high levels of lead were found in the children’s playground.

When Prefect for Paris, Michel Cadot, admitted that insufficient steps were taken by authorities to avoid contamination, clean-up work on the cathedral site ceased and the workers sent home. Work was due to restart this week (commencing 11 August) but has been delayed to 19 August.

The Robin Hood group lawsuit targets the “relevant authorities, including the diocese”, which it says “neglected to assist residents, visitors, and workers, allowing them to be exposed to the toxic fallout”. The group argues that authorities failed to take adequate measures to protect the public from the fallout and neglected to warn them about the risks of lead particles in the air.

Despite the introduction of new safety measures, Parisian officials have still rejected calls to cover the entire cathedral with cladding to contain the toxic lead particles. They argue this measure would be too expensive and complex.