Aerosols

The synthetic production of aerosols for various commercial purposes has become such a large industry that the term aerosol itself has taken on a new meaning. Average citizens who know little or nothing about the scientific aspects of aerosols recognize the term as referring to devices for dispensing a wide variety of products.

Aerosol technology is relatively simple in concept. A spray can is filled with a product to be delivered (such as paint), a propellant, and, sometimes, a carrier to help disperse the product. Pressing a button on the can releases a mixture of these components in the form of an aerosol.

The simplicity of this concept, however, masks some difficult technological problems involved in the manufacture of certain "spray" (aerosol) products. An aerosol pesticide, for example, must be formulated in such a way that a precise amount of poison is released, enough to kill pests, but not so much as to produce an environmental hazard. Similarly, a therapeutic spray such as a throat spray must deliver a carefully measured quantity of medication. In cases such as these, efforts must be taken to determine the optimal particle size and concentration in the aerosol by monitoring the CFC propellants, which destroy the ozone layer.

The production of commercial aerosols fell slightly in the late 1980s because of concerns about the ozone and other environmental effects. By 1992, however, their manufacture had rebounded. In that year 990 million container units (bottles and cans) of personal aerosol products and 695 million container units of household products were manufactured. In the early 1990s many states passed legislation limiting the volatile organic compounds (or VOCs) used in consumer product aerosols such as hairspray and spray paint. These limitations has forced the aerosol industry to seek alternate propellants and solvents. In many cases this substitution has resulted in inferior products from the standpoint of drying time and spray characteristics. The industry continued to struggle with these issues into the year 2000.