The area around Notre-Dame Cathedral in Paris was sealed off early on Tuesday as workers prepared to apply a special gel to absorb lead particles that seeped into the soil in the wake of the April 15 blaze.
Renovation work at the famed cathedral was halted last month over fears that workers could be exposed to lead poisoning after testing revealed dangerously high levels of contamination at the site and surrounding areas.
Hundreds of tonnes of lead in the roof and steeple melted during the fire that nearly destroyed the gothic masterpiece, with winds spreading the particles well beyond the church’s grounds.
After weeks of denying any poisoning risks, authorities admitted in late July that anti-contamination measures were insufficient, and two schools near the church were closed after hazardous lead levels were detected.
Since then officials have been racing to implement tougher safety measures for workers at the site, while deploying new methods to remove lead residue from school playgrounds.
Last week, workers dressed head-to-toe in white hazmat suits sprayed a blue-green gel onto the playground at the two closed schools on the Rue Saint-Benoit, where dozens of children had been attending summer daycare programmes.
According to city officials, the gel attracted and trapped the lead particles on the ground as it dried, and was later removed with high-pressure hoses.
That procedure and others will also be used on the square in front of Notre-Dame and on streets in the immediately vicinity.
Readings of more than 70 microgrammes per square metre indicate potential health hazards, but testing has found much higher levels at buildings as far as one kilometre from Notre-Dame.
In late July, the city revealed that some schools and daycares beyond a 500-metre perimeter of the church still showed isolated readings of more than 1,000 microgrammes on playgrounds or windowsills.
Critics have accused the city of failing to notify the public about the worrying results, while an environmental group has filed a lawsuit alleging that officials failed to sufficiently contain the contamination.
Others have urged authorities to cover the entire church with protective cladding to contain the particles, a system often used when removing asbestos.
City officials have rejected the proposal as too costly and complex.
But they have vowed that no schools will reopen in September unless the lead risk has been completely eradicated.
On Friday, Prefect Michel Cadot, the government’s top official for the Paris region, said renovation work at the cathedral would resume on August 19, provided the toxic lead is fully removed and the new safety measures are in place.