Abstract
The roof and spire of Notre-Dame cathedral in Paris that caught _re and
collapsed on April 15, 2019, were covered with 460 tons of lead (Pb).
Government reports documented Pb deposition immediately downwind of the
cathedral and a 20-fold increase in airborne Pb concentrations at a
distance of 50 km in the aftermath. For this study, we collected 100
samples of surface soil from tree pits, parks, and other sites in all
directions within 1 km of the cathedral. Concentrations of Pb measured
by X-ray uorescence range from 30 to 9000 mg/kg across the area, with a
higher proportion of elevated concentrations to the northwest of the
cathedral, in the direction of the wind prevailing during the fire. By
integrating these observations with a Gaussian process regression model,
we estimate that the average concentration of Pb in surface soil
downwind of the cathedral is 430 (95% interval, 300-590) mg/kg, nearly
double the average Pb concentration in the other directions of 240 (95%
interval, 170-320) mg/kg. The di_erence corresponds to an integrated
excess Pb inventory within a 1 km radius of 1.0 (95% interval, 0.5-1.5)
tons, about 0.2% of all the Pb covering the roof and spire. This is
over 6 times the estimated amount of Pb deposited downwind 1-50 km from
the cathedral. To what extent the concentrated fallout within 1 km
documented here temporarily exposed the downwind population to Pb is
di_cult to con_rm independently because too few soil, dust, and blood
samples were collected immediately after the fire.