Great point. I think if someone does something in the air over their property that causes harm to others, then they should be held accountable. These things would need to be worked out by individuals and I'm sure all sorts of innovative, voluntary solutions would be found.

Also, another question to think about would be.....if the claim is made that someone doesn't have property rights to the air above their land, then who would have claim over it? Who would take responsibility for that air space?