How Much Environmental Damage Will Notre Dame’s Lead Roof Cause?

Nicolas Liponne/NurPhoto via ZUMA

We get questions:

@ClaraJeffery @marynmck Know any environmental journos who want to take this story? I’ve been slightly obsessing about if for days now. It was 210 TONS of lead. It went *somewhere* …
— Charlotte M. Freeman (@charlottemf406) April 18, 2019

That’s a lot of lead. And I am not an expert in how lead circulates in the atmosphere. However, for two reasons I suspect this isn’t too big a concern:

Most of the lead melted and fell into the cathedral. I can’t put a number to this, but I imagine that only a tiny fraction was carried away into the atmosphere. Pure lead is quite heavy.¹
It’s a one-time occurrence. Lead mostly poses a danger when children are exposed to it for long periods of time. In this case, however, they’ll probably be exposed for only a few days before it all settles or drifts away.

I too would like to hear from an expert about this, but in the meantime my best guess is that the release of lead into the atmosphere is a fairly minor issue.
Note that I’m talking here about the effect on the area surrounding the cathedral. Needless to say, lead contamination inside the cathedral is likely to be a big problem for the cleanup crew.
¹As opposed to the lead in gasoline, which comes in the form of tetraethyl lead. This molecule contains 20 hydrogen atoms, 8 carbon atoms, and one lead atom, which makes it relatively light. It’s still heavier than air, but not so much that it can’t drift quite a distance on wind currents.