Notre-Dame de Paris: should we be worried about the future lead roof of the cathedral?

When it went up in smoke in 2019, the lead roof of Notre-Dame Cathedral in Paris initially caused great concern, that of lead pollution. And for good reason: an unknown quantity of metal dust then spread throughout the capital, posing the threat of poisoning. As a reminder, lead poisoning, also called lead poisoning, can have very serious consequences, particularly in children, with neurological effects and developmental delays. But as the renovation project enters its home stretch, it is now another subject which is causing debate: the installation of a new lead roof, recorded as soon as the choice was made to rebuild the cathedral Is the identical a wise choice? Should we be concerned about possible health repercussions?

Questioned by Le Figaro, Philippe Jost, who chairs the public establishment responsible for the conservation and restoration of Notre-Dame, wants to be reassuring: “We, obviously, do things in compliance with the law and regulations in all areas concerned, and no one's health is put at risk. In addition to new fire protection of the highest level, including a misting system in the attic which is a first in a cathedral in France, we will innovate by installing a system for collecting and filtering rainwater which will have run off onto the roof. roof of the cathedral.

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The subject of pollution in the capital is far from being anecdotal. “Lead pollution in Paris is real, but the problem dates back well before the Notre-Dame fire,” explained researcher at the Climate and Environmental Sciences Laboratory Sophie Ayrault to Le Figaro last January. In June 2019, two months after the fire, the Regional Health Agency (ARS) of Île-de-France organized 1,200 screenings in schools in districts exposed to smoke. While 13 cases of lead poisoning were detected, all were linked to lead exposure independent of the fire. Did this have a health impact? Sophie Ayrault's team carried out work on the subject after having succeeded in differentiating lead from the cathedral from ambient lead, and comparing the quantities of different leads in samples taken in the capital. Analyzes are underway and the results should be published quickly. But several indications suggest that this pollution would be quite marginal. For example, lead from the cathedral was not present at all in the honeys analyzed in the six months after the fire.

Although the impact of the fire is probably low, “it may have had the merit of bringing the problem back into the spotlight,” underlines Dr Jérôme Langrand, head of department at the Paris Poison Control and Toxicovigilance Center. In this context, is adding a lead roof a good thing? If the goal is to eradicate lead from the capital, the answer is no. But if we just look at the health impact of this lead, it will be very marginal, if not zero.”

And for good reason, lead is present almost everywhere in Paris, on roofs (even if roofs exclusively made of lead remain rare), balconies, in paints, certain pipes... Lead remains in fact a very good insulator and is very resistant to wear, it therefore continues to be used in construction even if this use is very regulated.

As for the population's exposure, enormous progress has been made over the last two decades, particularly with the abandonment of leaded gasoline in the 1990s. "Generally speaking, there has been an awareness of the danger and we have put in place an effective prevention policy, explains Dr Jérôme Langrand. With analyzes of lead levels in the children's blood and rehousing if they lived in unsanitary housing. Which bore fruit.” However, lead remains very present. The latest estimates (1997-2002) reveal that the Seine receives more than 100 tonnes of lead per year, produced mainly by urban areas. “After the fire, we noticed that this problem also affected children from privileged backgrounds,” continues the doctor. We must therefore continue to maintain a high degree of vigilance. What is done, cases of poisoning remain at low levels.”