I hate to be a total killjoy here, but don't you ever wonder what the hell happens to all those errant balloons sent off into the sky?
Do you think they just keep going out of the earth's atmosphere and travel into space? Well, they don't.
They travel for miles and then land back down on earth, usually semi-inflated or popped into pieces. If a balloon lands in the ocean it creates a great risk for marine wildlife, particularly marine turtles and seabirds.
They mistake the flotsam for food (like a jellyfish) and swallow the pieces or get tangled up and drown. Some whales and dolphins have died after eating balloons as it blocks up their digestive systems.
It's bad enough that all that crap lands back on the earth, but the fact that it endangers some of my favorite critters is really disturbing.
Anyway, if you would like to learn more about how released balloons are a danger to wildlife and the environment, read this.