The aerosol spray can—used for many years to apply everything from deodorant to paint to insecticides--dates back to 1926, when Norwegian inventor Eric Rotheim discovered that a product could be contained in and sprayed from an aluminum can injected with gas or liquid to build pressure. In 1939, American Julian S. Kahn received a patent for a disposable spray can, but the product remained largely undeveloped,even after Lyle David Goodhue,credited as the inventor of the spray can,earned a patent for a refillable aerosol spray can in 1941. A breakthrough came in 1949 when Bronx machine shop proprietor Robert H. Abplanalp developed a cheap, efficient valve that facilitated widespread use of the can. The propellants in aerosol spray cans--usually liquified gases such as hydrocarbons,carbon dioxide,or nitrous oxide--are mixed with the contents of the can and pressure-sealed for eventual release through a valve.
Although products like shaving cream or whipped cream also come in pressurized cans, they are not actually aerosols; they contain gases suspended in liquid bases rather than solids or liquids suspended in gaseous bases. Chloroflourocarbons (CFCs).During the 1970s controversy developed over the use of these freon-type gas propellants. Scientists began to fear that chloroflourocarbons released in large quantities posed a significant danger to the environment because they could break down and react with chlorine. Such a reaction could destroy some of the protective ozone layer in the upper atmosphere, which shields the earth from harmful solar radiation. In 1978, the United States government banned the use of certain chloroflourocarbons,in connection with the first global environmental agreement,the Montreal Protocol,and manufacturers were forced to find other propellants for their product. A complete phaseout of CFCs by the year 2005 in developed countries is included in the Montreal agreement.In the mid-1980s as public concern grew on the issue of an Antarctic Ozone Hole,clearly detected in NASA photographs substitutions were made for propellants using HCFCs including Liquefied Petroleum Gas (LPG),a flammable mixture which requires careful disposal, Di Methyl Ether largely present in air fresheners and personal care products,and non soluble gasses,an alternative to LPG and soluble compressed gases. In response to continuing concerns about environmental and fire safety hazards of aerosol can recycling, a 1996 study was conducted by the Factory Mutual Research Corporation (FMRC) an independent fire engineering research group. The study concluded that recycling empty aerosol cans does not increase fire risk at the recycling station,although some risk adheres to cans that are not emptied.
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