Shotgun blasts into the air... threat to others?

In another thread, I mentioned that an acquaintance had driven some potential looters away with a shotgun blast into the air. Another poster noted that a shotgun fired into the air consitituted a "warning shot," and the falling shot posed a threat to third parties.

I am well aware that "warning shots" are generally a bad idea, and I explain why when teaching my concealed carry classes. Rather than start another re-hash of the wisdom of "warning shots," I'd like to ask different question:

Does falling shot pose the same threat as falling bullets?

I admit ignorance on this issue. I always thought that shot decelerated rather quickly, but then, shot is just a smaller version of a musket ball, and I suspect those were lethal at far greater ranges than they were accurate. It seems to me that steel or lead shot, dropped from a high altitude, would reach some terminal velocity, and this velocity may not be lethal. On the other hand, I think I've read that kids who used to drop marbles from high-rise apartments could kill a pedestrian on the sidewalks below, and marbles aren't as dense as metal shot. (Gee, do kids even have marbles anymore? Probably not: Choking hazard.)

So again, is falling shot a hazard? Does it matter whether it's double-ought buck or birdshot? (Let's not discuss slugs. I think those are a different issue.)

(And again, the question isn't about the wisdom or legality of shotgun blasts into the air.)

- - - Yoda

For Kleanbore

Here is the context of the story of the shotgun blast into the air:

It was after one of several Hurricanes that had hit the Florida Panhandle that year. There was no electricity, and the owner of a gun store/pawn shop decided to guard his establishment. It was after midnight and it was pitch black, and if you've never been in a region (region, not locale) where there is zero power, you can't imagine how utterly black everything is, and how busy the cops might be.

The owner and his son were standing near a corner of the store, in the alley behind it, and they heard--but could not see--two men discussing how to break a lock on a storage unit behind the store. Rather than illuminate them with a flashlight or challenge them, he just fired a shot into the air. He heard them run off and trip over something.

I didn't think to ask what sort of load the shotgun had.

Was this tactically smart? I think it was smart enough. The threat went away, and no one was hurt.

Again, I know the arguments against warning shots, but in this case, I think it was a reasonable move.

- - - Yoda