system
Given the following post, respond as if you're commenting on Reddit:
human
[BvS] Why couldn't Superman see thru the smoke bomb Batman threw? Was is lead smoke?
gpt
> Was it lead smoke?

Yes.  During the Bruce training / preparation montage, he sets his three grenades in the foreground.  You can see "Pb" scratched into the side of the grenade.  Pb is the periodic abbreviation / chemical symbol (from the latin plumbum) for the element Lead (atomic number 82).