In 2019, tragedy struck the city of Paris as the world-famous cathedral at Notre-Dame set fire following an accident, transforming this historic site into a flaming inferno. A new study published in the journal GeoHealth has assessed the fallout from the blaze and found that the 460 tons of lead tiles on the roof of the cathedral triggered a 20-fold increase in airborne lead concentrations in neighboring Paris at a distance of 50 kilometers (31 miles) from the fire. Their findings highlight concerns about public health and the swift communication of relevant threats in the wake of such disasters.

The fire took place on April 15, 2019, at around 6pm Paris time, beginning beneath the roof of the cathedral. By the time it was extinguished, the spire had collapsed and most of the roof, which was covered in lead tiles, had been destroyed. The fire injected this lead into the air where it was carried by smoke and wind across neighboring Paris.

To investigate the reach of this mobilized lead, the study took surface soil samples from locations in all directions within a 1-kilometer (0.6 miles) radius of the cathedral. Their findings revealed elevated levels of lead in locations downwind of the blaze, indicating that the soil had preserved some of the roof’s released lead. The discovery raised questions as to the dangers posed by the concentrations of lead that were airborne shortly after the fire. Leaks of lead are of significant importance as exposure to even very small amounts of environmental lead can negatively impact the cognitive development of children. 

Their estimations put the amount of deposited lead within the 1-kilometer (0.6-mile) radius following the fire at around 1,000 kilograms (one metric ton), much higher than an early government report which said that just 150 kilograms had been deposited.

A blood survey following the accident reported few children with a significantly raised lead result, but the study authors highlight that a delay in testing and opting for volunteers could mean these findings are inaccurate. They suggest that swifter and more widespread environmental testing carried out immediately after the blaze would have given a much better indication of the scale of the problem and informed better decisions on how to best protect Paris’ residents.

[H/T: Massive Science]