

Thats a good point, not even turboprops are leaded if I remember right.
Obviously it’d require a lot of study to definitively say the impact of the lead, but I’m convinced the impact wouldn’t be able to compare to natural levels in that atmospheric environment. Like we love our planes, but its still energetically really difficult for us to get them up there - but space rocks can have a hard time NOT burning up in our atmosphere. And lead is a larger than uniform part of our universe because its atomic stability, so odds are (IMO) atmospheres relatively lead-y, but have been for centuries.
That and the difficulty creating hotspots in such a turbulent environment makes it required to increase the entire atmosphere’s lead content to increase any one area to dangerous levels.

Electron orbits do have a spin direction, its one of 4 quantum numbers used to describe them.