Helium is used to make balloons float, and comes in cylinders of various sizes. It is colourless and odourless and will not interact with any other gas. Used correctly helium is perfectly safe. However helium should NEVER be inhaled as it is an asphyxiant so can kill. It can also bring on asthma attacks and rupture vocal cords when used to create a squeaky voice.
Balloon Releases & Foil Balloons
Foil balloons should NEVER be released either singularly or in multiples. Due to their make up they are NOT biodegradable and can harm or kill wildlife. They are a also a conductor of electricity so if they get caught in a power line could cause a power cut.
Latex balloons however are biodegradable (see below). If used for a balloon release string or ribbon should not be attached. Releasing a large quantity of latex balloons could require special permission from the Civil Aviation Authority. If you are using a professional balloon supplier for your release they will obtain any permission required.
Latex Balloons & The Environment
Latex balloons are made from 100% natural latex and will biodegrade in about the same time as an oak leaf. For this reason they are safe to release into the atmosphere without ribbon or string, where they will float to a height of around 20000 feet then shatter into small pieces.
The latex used to make balloons is extracted from cloned rubber trees planted and harvested in tropical regions. Rubber trees are planted in very precise rows 22ft apart. After approximately 6 years the trees are ready to be tapped. This means the natural rubber can be extracted and taken to the factory to produce the latex needed for balloons. This method is also a great way of saving rain forests as villagers can earn a wage by farming the trees instead of cutting them down.