Later in that article: “But Notre-Dame was not the only location to be affected,” Toullier pointed out. “Lead levels were very high all around the cathedra

Later in that article: “But Notre-Dame was not the only location to be affected,” Toullier pointed out. “Lead levels were very high all around the cathedral, on metro platforms, in bookshops on the Place Saint-Michel and even in surrounding schools.” At the end of summer 2019, Notre-Dame Lead reported levels of up to 123,000 μg/m², which represented 25 times the "standard" threshold of 5,000 µg/m² set by the regional health authority ARS, at the Place Saint-Michel, a 10-minute walk from the cathedral. “Yet no significant clean-up operation was carried out. It was as if the problem didn’t exist,” Toullier lamented. “But what about run-off water from the roof, which will be laden with lead?” asked Thébaud-Mony. In a notice published in January 2021, the French High Council for Public Health estimated that “the roof of Notre-Dame alone … would emit around 21kg of lead per year (about two tonnes per century) in run-off water”. “Lead could have been replaced by another substance like zinc or copper,” said Thébaud-Mony. “When alternatives exist, why choose lead and risk human health?” This was the case for the Chartres cathedral, destroyed by a fire in 1836. The original structure had lead roofing, which was replaced by copper when it was rebuilt. Though perceived as less stable, copper is significantly less toxic.