Your article about the power outage due to mylar balloons was informative, but there are other important aspects which make balloons dangerous to animals and our environment. Most balloons are mylar or latex.
Latex degrades in 1-4 years, while mylar is non-biodegradable.
They are a source of litter in our oceans and on land. Both marine and land animals can mistake deflated balloons as food, and once ingested can cause blockages. Small children have also been known to ingest uninflated balloons.
The strings or ribbons attached to balloons can be just as dangerous also. Birds become entangled, and sea turtles, seals, and dolphins have flippers and fins snared, which reduces their ability to move and eat, with serious consequences.
Flags, banners, bubbles or streamers are a good alternative to balloons. When using balloons, please make sure they are disposed of properly.