Bullets falling from the air are not lethal. That is anything shot over a 60 degree angle or so. And shotguns only have a range of 100 yards or so and the shot is going too slow to be lethal. I would like to point out that bullets shot at about a 45 degree range may be lethal to about a mile so pointing a rifle in the air without a lot of uninhabited land is unwise. However it is perfectly safe to point a shotgun in the air for about 100 yards around you.