It’s 8 April, and today we commemorate the day way, way back in 1862, the American John D Lynde received a US patent for the first aerosol dispenser, described in the patent as an “improved bottle for aerated liquids”. While the concept dates back as far as 1790, it appears this was the first time it was patented.

According to the The Columbia Electronic Encyclopedia, an aerosol dispenser, also known as a spray dispenser when dispensing larger particles, is basically a “device designed to produce a fine spray of liquid or solid particles that can be suspended in a gas such as the atmosphere.” The dispenser is often a pressurised container that holds the substance to be dispersed together with a propellant. It has a valve release mechanism – when the valve is opened, the propellant forces the substance through a small hole, and it is distributed as a fine mist spray. Various propellants have been used over the years, with chlorofluorocarbons (CFCs) being a common choice until it was banned in 1989 through the Montreal Protocol because of its detrimental effect on the earth’s ozone layer. Newer, less destructive propellants include propane, butane and other volatile hydrocarbons. The downside of these is that they are flammable. Spray dispensers containing foodstuffs (cooking spray, whipped cream etc) often use nitrous oxide or carbon dioxide as propellant, while medical aerosols such as asthma inhalers use hydrofluoroalkanes.

An even less harmful form of aerosol dispenser, known as an ‘atomiser’, uses a hand/finger operated pump, rather than a stored gas, to produce pressure in the container in order to propel the contents as a spray.