Maybe you went to the Homecoming game this night, or you've been to football games and rallies and the whatnot where balloons are absolutely everywhere. They're around all the rails on the side, in those pretty-looking balloon arches... and flying off into the sky.
Let's take things back to physics here: what goes up must come down. Those balloons which become tiny dots in the sky before blinking out of view are going to eventually burst into small fragments that will spread all over our world. Releasing balloons is littering, and the dangerous effects of it can be seen in the deaths of wild, domestic, and farm animals, along with all the creatures of the sea who are unfortunate enough to think that a balloon fragment is a tasty morsel.
Maybe you've heard that latex balloons decompose at the same rate as an oak leaf; which is true. However, the decomposition of an oak leaf is approximately six months (varies under different conditions). Would you leave a piece of trash lying in the same place for six months? Would you toss your trash on the floor?
Releasing balloons into the environment, whether in small or large quantities, is harmful to the world; the world that we need to take better care of. Do your part, and be sure to keep those balloons out of the sky!