A governmental health agency published a report on 19 July, including on page 30 a map made by the police of the lead depositshttps://www.iledefrance.ars.sante.fr/system/files/2019-07/DP-point-de-situation-Notre-Dame-de-Paris_0.pdf
. The units are really µg/m2
and up to 1.3g/m2 lead deposited
I didn't find in the report when the measurements were made. I believe it was in July
, after several rains had cleaned the surfaces.
The figures tell how much lead gets dissolved by HCl under conditions that simulate the digestion, which I believe is a small fraction of PbO. Though, at least Wiki tells "Inhalation is a major source"https://fr.wikipedia.org/wiki/Saturnisme#Air_ambiant
so the poisoning of people present during the fire may be much worse.
Multiplying the area by the surface density, I get only 1kg deposited right around the cathedral and 2kg on two districts downwind. Though, intuition shouts that the big dense yellow smoke that escaped for hours contained much more PbO. The figures don't add up
. Probably most lead oxide deposited farther downstream: excess lead was observed in the air outside Paris. And most lead went to the sewage before the measurements.
To illustrate 1g/m2
, I weighed dust after cleaning a room: 1.9g over 30m2 is yuk
, and this isn't poison. At the cathedral, they got nearly that amount on 1m2
. Pictures appended.
How unhealthy? Imagine that away from Notre-Dame, at Saint-Michel square that kept open and uncleaned, someone wanting to make photos lays his 0.02m2
croque-monsieur on the foutain's rim, then eats it. 30mg/m2
were measured (but when?), so he ingests 600µg of digestible lead equivalent. If he's an adult with 6L blood, his concentration climbs to 10 µg/dl, the upper limit set by the Center for Disease Control
. On the cathedral's square, concentrations were 20* higher.
The concentration may have been much higher right after the fire, and poisoning over the lungs worse.