Helium is formed very slowly within the earth from the radioactive decay of Uranium and other elements. It is very rare on earth, although abundant in the universe as a whole (the second most common element after Hydrogen). It has many useful uses, including deep-sea breathing systems, superconducting magnets, and many other specialist applications. It is used in airships and blimps, as it is safer than Hydrogen because it is inert (does not react or explode). It is also popular in party balloons, as it is lighter than air, and makes your voice sound funny when you breathe it in and talk. But given its rarity, and the fact there are limited production sites for Helium, many people say it is irresponsible to use it frivolously.

There are basically two types of balloons, foil and latex. Foil balloons are made from nylon covered with a thin layer of aluminium. They do not biodegrade. Latex balloons, on the other hand, are made from a natural substance and biodegrade in around 6 months under normal conditions.

If you are thinking of a balloon release for charity, or just for fun, take a look at the NABAS guidelines.