aerosol dispenser, 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 commonly consists of a container that holds under pressure the substance to be dispersed (e.g., paints, insecticides, medications, and hair sprays) and a liquefied gas propellant. When a valve is released, the propellant forces the substance through an atomizer and out of the dispenser in the form of a fine spray. These devices are more properly termed spray dispensers rather than aerosol dispensers because the particles of the dispersed substance are usually larger than the particles of a true aerosol (see colloid), such as a fog or a smoke. Freon was the most common aerosol propellant, but its use has been banned because it is believed to contribute to destruction of the ozone layer of the stratosphere; common propellants now include propane, butane, and other hydrocarbons.

aerosol: see colloid.

System of tiny liquid or solid particles evenly distributed in a finely divided state through a gas, usually air. Aerosol particles participate in chemical processes and influence the electrical properties of the atmosphere. Though true aerosol particles range in diameter from a few nanometres to about one micrometre, the term is commonly used to refer to fog or cloud droplets and dust particles, which can have diameters of more than 100 micrometres. Seealso colloid; emulsion.

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