Eventually they pop or deflate, and fall on land or into the ocean. If it falls on land, animals like dogs, cats, etc... may try to eat it and choke to death. If it falls into the ocean, sea creatures like dolphins, fish, seals, etc... may try to eat it and choke to death.
I don't think it's considered littering, therefore not a crime... but I think it should be. Don't you think it's just as bad as throwing a piece of paper or a cigarette down on the side walk, or in a park?
Helium is a gas that isn't good for the ozone layer. Though, the amount of helium in a normal sized balloon is not gonna do much. Also the rubber in the balloon can be eaten by birds or fish and kill them.
I'd say it IS littering because when the balloon pops, the rubber has to land somewhere...
I think it has something to do with space junk, but not sure
Because they float away. :[