is the risk of lead pollution completely eliminated?

Emmanuel Macron makes a final visit to the Notre-Dame construction site, Friday November 29, a few days before the official reopening of the fully restored cathedral. It took five years of work to restore the building to its splendor, after the fire which ravaged it on April 15, 2019. The The fire, which started from the framework, then melted the cover and the lead spire of the monument. Centuries of history gone up in smoke and “400 tons of lead released into the air”, summarizes Benoît Martin, general secretary of the CGT Paris.

Since the fire, the trade unionist has denounced the lack of reaction from the authorities to protect site employees and local residents from the toxicity of lead, the ingestion or inhalation of which can cause lead poisoning. The most serious cases of contamination are accompanied by anemia, hypertension, kidney deficiency, or even – in pregnant women – an alteration of fetal development, explains the National Institute of Health and Medical Research. This clinical picture is all the more worrying as there is no non-toxicity threshold. “Lead is toxic to children, pregnant women and adults, even at low concentrations,” develops Inserm.

Alongside the Henri Pézerat association, which defends workers against health attacks, and two families of local residents, the CGT Paris filed a complaint against others” in June 2022. Complaint for which the investigation is still in progress, the Paris prosecutor’s office informed franceinfo, contacted at the end of November.

An exceptional concentration of this heavy metal was measured around the burned building a few weeks after the disaster. From, the Ile-de-France Regional Health Agency (ARS) feeds a card displaying weekly direct debit statements. We learn, for example, that the cathedral counted up to 611,450 micrograms of lead dust per square meter (µg/m²) between April and September 2019. For comparison, the ARS considers that health action is required from 5,000 µg/m². After the fire, a cloud loaded with lead particles also crossed the heart of the capital towards the west. This toxic plume reached as far as Yvelines, according to modeling carried out in 2019 by Ineris (French Institute of Industrial Environment and Risks) (PDF).

Five years after the publication of this alarming data, the latest samples taken around the cathedral which are available, dating from July 2024, are, with the exception of one value, below the 5,000 µg/m². Various lead dust cleanups have been undertaken in recent years in the sector, but “he It is certain that there continues to be pollution all around.according to Annie Thébaud-Mony, dhonorary research director at Inserm and president of the Henri Pézerat association.

Questioned by franceinfo on this point, the Paris police headquarters argues that additional sampling campaigns “are underway outside and inside the cathedral with a view to [l]upon reopening [de Notre-Dame]”. It is about “surface samples taken with moistened wipes”, in which the central laboratory of the police headquarters participates. The results will be posted online on the website of the Ile-de-France Regional Health Agency. The ARS also specifies that it will recommend continued environmental monitoring after the reopening of Notre-Dame. “Indeed, in addition to the new roof and the lead spire, work is to come after December 8 (…) Future work on the outskirts of Notre-Dame could potentially remobilize the ‘historic’ pollution, that is- i.e. the presence of lead dust dating from the fire under the resin placed on the square in 2020”, she justifies.

Studies are also underway to try to precisely assess the impact of this fire on the environment and the health of Ile-de-France residents. The Climate and Environmental Sciences Laboratory of the Atomic Energy Commission (CEA) managed to identify the imprint of the Notre-Dame fire in the signatures of the various lead sources in the capital, but scientists are not yet able “to distinguish it in samples taken”, explains research director Sophie Ayrault. “The time of science is a very long time.”procrastinates the expert in the face of the thirst for answers from associative actors.

Notre-Dame has not said goodbye to the use of lead. The architects responsible for the restoration of the cathedral opted for an identical reconstruction, right down to the choice of materials. A decision validated unanimously by the National Commission for Heritage and Architecture on July 9, 2020, but vehemently denounced by Mathé Toullier, president of the Association of Families Victims of Lead Poisoning: “It is above all an easy solution. The ambition for the reconstruction should not have been to do it as quickly as possible, but to do the best possible, with other materials.”

A position shared by the various associative actors united in the “Plomb Notre-Dame” collective. “To the pollution linked to the fire is now added that of the release of lead dust from the new roof and the spire”we can read in their press release dated mid-April. Marie-Christine Gromaire, research director at the Water, Environment and Urban Systems Laboratory (Leesu), conducted, with the National School of Bridges and Roads (ENPC), an unprecedented study between autumn 2021 and June 2023 to quantify the lead which passes into the rainwater falling on the lead roofs of Notre-Dame. “Ocould not estimate that in one year, the roof would emit nearly 10 kilos of lead”figures the researcher. All through a simple phenomenon of runoff. “This corresponds to a locally very significant occasional emission of lead which could accumulate in the sewers and in the sediments”, continues Marie-Christine Gromaire. In the event of heavy rain, the lead would then end up in the Seine, contributing to the deterioration of the quality of the river’s water. “If we compare this figure [de 10 kilos] with all the lead flows emitted by the Paris metropolitan area over a year, this remains quite little”nevertheless qualifies the research director.

The problem of lead runoff has been identified by the authorities. The new lead roof covering was conditioned by the regional prefect upon completion “a device for collecting runoff water on the lead roof and, secondly, a device for filtering and purifying this water”, detailed the Ministry of Culture. Asked about the progress of this runoff water depollution project a few days before the reopening of the building, the public establishment responsible for the restoration of Notre-Dame did not respond to our requests. The ARS Ile-de-France confirms for its part that a “device for collecting and treating runoff water from the lead roof will be implemented by the public establishment”, and specifies that it is responsible for monitoring its implementation.

“There are two ways of spreading lead from a leaded roof: either by leaching by rain, or by fire.”

Sophie Ayrault, research director at the CEA Climate and Environmental Sciences Laboratory

at franceinfo

By restoring identically, with the same flammable materials, a monument of unusual dimensions, the builders also risk a repeat of the disaster scenario of April 15, 2019. To prevent any new fires, important fire safety measures have been taken. A misting mechanism has been installed along the frame, a new fire detection system was put in place and the attic structure was reinforced, list the site managers with France 3 Ile-de-France. In the opinion of the various scientific and associative actors contacted by franceinfo, the 2019 fire will have at least made it possible to alert the world of construction and heritage to the challenges of lead pollution in an attempt to avoid a new disaster .