Lead fallout from Notre Dame fire was likely overlooked
A ton of lead dust may have been deposited near the cathedral

Date:
July 9, 2020
Source:
Earth Institute at Columbia University
Summary:
A new study used soil samples collected from neighborhoods around
the cathedral to estimate local amounts of lead fallout from
the fire.



FULL STORY ==========================================================================
On April 15, 2019, the world watched helplessly as black and yellow smoke billowed from the Notre Dame cathedral in Paris. The fire started just
below the cathedral's roof and spire, which were covered in 460 tons
of lead -- a neurotoxic metal, dangerous especially to children, and
the source of the yellow smoke that rose from the fire for hours. The
cathedral is being restored, but questions have remained about how much
lead the fire emitted into the surrounding neighborhoods, and how much
of a threat it posed to the health of people living nearby.


==========================================================================
A new study, published today in GeoHealth, used soil samples collected
from neighborhoods around the cathedral to estimate local amounts of lead fallout from the fire. Lead levels in the soil samples indicated that
nearly a ton of lead dust dropped down within one kilometer (0.6 miles)
of the site, and areas downwind of the fire had double the lead levels
than sites that were outside the path of the smoke plume. The study
concludes that, for a brief time, people residing within a kilometer
and downwind of the fire were probably more exposed to lead fallout than measurements by French authorities indicated.

Early evidence suggested that the fire increased lead exposure
in Paris. Air quality measurements taken 50 kilometers away from
the cathedral found that lead particulates in the air were 20 times
higher than usual in the week after the fire. However, a small set of measurements by France's Regional Health Agency, posted weeks after the
fire, found that all the samples collected outside of the out-of-bounds
area around the cathedral had lead levels below France's limit of 300 milligrams per kilogram of soil. At the time, there were fears that
the health agency was underplaying the potential health impacts and not
being transparent enough.

"There was a controversy -- were children being exposed or not from
this fallout?" said Lex van Geen, a geochemist at Columbia University's
Lamont- Doherty Earth Observatory and lead author on the new study. "So
I thought, whether I get a 'yes' or a 'no,' it's worth documenting."
In December 2019 and February 2020, van Geen collected 100 soil samples
from tree pits, parks and other locations around the cathedral, and in particular to the northwest, where most of the smoke traveled on the
day of the fire. When lead enters soil, it tends to stay put, so it can preserve the signal of the fallout for much longer than hard surfaces
such as roads and sidewalks, which get swept and flushed by rain.

"It wasn't a particularly glamorous expedition," said van Geen. "I got
plenty of strange looks from people wondering why this old guy was
scooping up soil, trying to avoid the dog poop, and putting some of
the soil in paper bags. But it got done." Non-contaminated soil would
be expected to contain less than less than 100 milligrams of lead per
kilogram of soil. However, in samples collected within a kilometer the cathedral's remains, the levels averaged 200 mg/kg. And in the northwest direction downwind of the fire, the lead was significantly higher,
averaging nearly 430 mg/kg -- double that of the surrounding area,
and surpassing France's 300 mg/kg limit.

Because the sample sites weren't uniformly distributed, co-authors Yuling
Yao and Andrew Gelman from Columbia University's Statistics Department
used statistical methods to predict the overall distribution of lead,
calculate the averages inside and outside of the plume, and estimate the
total amount of lead that fell near the fire. By their calculations,
1,000 kilograms (2,200 pounds) of lead settled within a kilometer of
the cathedral. That's six times higher than the current estimate for
the amount of lead fallout between 1 and 20 kilometers of the site.

"Our final estimation of the total amount of excess lead is much
larger compared with what has been reported earlier by other teams,"
said Yao. "Of course, we are measuring slightly different things, but ultimately all disagreement in scientific findings shall be validated by
more data, especially when they have profound policy and public health consequences. I hope our work sheds some light in that direction." It is difficult to ascertain how this lead may have affected human health,
because too few soil, dust, and blood samples were collected immediately
after the fire, said van Geen. The impacts are likely much lower than
those of leaded gasoline, which was entirely phased out by the year
2000. Nevertheless, lead could have posed a brief but significant health
hazard to children living downwind of the fire.

On June 4, seven weeks after the fire, the French government made
blood tests available at a local hospital on an on-demand basis. This
only occurred after a child in a nearby apartment was found to have
a concerning level of lead in their blood. (Subsequent investigation
identified a different source of lead as the more likely culprit in this
case.) Soil and dust tests were similarly delayed and limited in scope.

To van Geen, the government showed it had the means to respond but it
didn't do so quickly enough. He says that the urgency of the situation
should have been more clearly conveyed with pro-active collection and
posting of environmental and blood-lead data. This would have induced
more parents downwind of the fire to remove indoor dust with wet wipes
at home and prevent kids from playing in soil, thereby reducing their
chances of exposure.


========================================================================== Story Source: Materials provided by
Earth_Institute_at_Columbia_University. Original written by Sarah
Fecht. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Alexander Geen, Yuling Yao, Tyler Ellis, Andrew Gelman. Fallout
of Lead
over Paris from the 2019 Notre‐Dame Cathedral Fire. GeoHealth,
2020; DOI: 10.1029/2020GH000279 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200709113525.htm

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