They have also been equated with automobiles and smokestacks in terms of smog potential. None of these claims are true, yet many Americans, rightfully concerned about the environment, perceive aerosols as a threat to clean air. Much of the confusion is due to outdated and misunderstood data.
Aerosols are very fine particles of liquid or solid substances suspended in air.
Fog, for example, is a natural aerosol. In aerosol packaging, the substance to be sprayed is propelled through a valve as a fine mist or a foam. This provides a safe, efficient means of dispensing thousands of consumer products such as shaving cream, hair spray, paint, and anti-perspirants. Fifty years ago, U.S. Department of Agriculture scientists developed the principle of pressurized insect spray. Refinements to containers, valves, propellants, and formulas have broadened the range of aerosol products and widened consumer acceptance.