CFC’S (Chlorofluorocarbons) and Freon have been the major propellants of Aerosol spray cans and are widely used. In 1970s, scientists found out that the ozone layer nearing Antarctica was thinning and some places showed ozone holes from where the ozone layer has been eliminated completely. This alarmed the scientists who traced CFC as the main reason for this occurrence as the depletion was more due to the reaction of chlorine.
Since ozone layers protect our earth from the harmful rays of the Sun, they are very important. With the depletion in ozone layer, today mankind is facing severe consequences in the form of global warming and harmful diseases like skin cancer etc. The U.S government banned the use of CFC in the aerosol spray cans in 1978 which was followed by banning this material by several other countries.
Aerosol spray can was invented in 1926 by an inventor. Eric Rotheim from Norway.
Just as it is with every invention, when new things are developed they catch up fast without considering the pros and cons. At the initial stage it was a composition which was put in an aluminum can and was injected with a gas or liquid so as to build pressure inside the can. From then on it has been used to apply so many things like paint, insecticide or even a deodorant. The disposable spray can was patented by Julian S. Kahn, an American in 1939 and the refillable aerosol spray can was patented by Lyle David Goodhue in 1941 who was also its inventor. But even then the use of these can was not widespread. The invention took off when Robert H. Abplanalp, the proprietor of Bronx machine shop created an efficient yet cheap valve for the can in 1949.
Mostly liquefied gases like nitrous oxide, hydrocarbons, carbon dioxide are blended with the Aerosol spray can content and are pressure sealed in such a way that when the valve is turned open and pressure is released the content from the can comes out. These liquefied gases are also called as propellants. Whipped creams and jams and also shaving creams use the same pressure-seal technology, but the content is not aerosols. Instead in these cans gases are kept in suspension in the liquid bases whereas in aerosol spray can liquids or solids are usually suspended the gaseous base.
Owing to the problem created by CFC, the main propellant of aerosol spray can during the 50’s and 60’s, Montreal Protocol, an international treaty that suggested the reduction in the use of ozone depletion causing substances was made. In 1989, almost 93 nations came together to help developing nations switch over to more economical options for replacing CFC in aerosol spray cans. It was decided in the Montreal protocol that by 2005, use of CFC should be completely stopped. During the 1980’s NASA introduced the latest ozone layer depletion in the Antarctica which was caused by the substitute propellants of CFC. The propellants which were found to be causing this grave problem was substituted with HCFC’s like Liquefied Petroleum Gas (LPG)- known to be highly flammable and careful supervision for disposition , Di Methyl Ether which is mostly used in personal care products or air fresheners, and non soluble gases which are mostly used as a substitute for LPG and compressed soluble gases.
The Factory Mutual Research Corporation (FMRC) which is a self motivated fire engineering research group conducted a research in 1996 to study the fire safety hazards which can be caused during the recycling of aerosol spray can. The study concluded that recycling of fully emptied cans does not cause any fire hazards.