A well-known campaign against chlorofluorocarbons in aerosols in the 1970s led to continued association of the chemical with aerosol sprays. However, this issue was entirely resolved, and aerosols are no longer a threat to the ozone layer. However, they are still not beneficial to the environment as they are one of many products that contribute to global warming and smog problems.
Originally, many aerosol products contained a man-made chemical known as CFC, or Freon, that propelled products out of the can. Scientists eventually discovered that CFCs depleted ozone in the atmosphere, which led to a highly publicized campaign against CFCs. Businesses agreed to stop manufacturing the chemicals in the late 1970s, and it's now illegal to sell products with CFCs in the US.
The Montreal Protocol of 1987 was also a landmark piece of legislation in banning the use of CFCs worldwide, and scientists estimate that 90 percent of the phase out of CFCs is complete.
In place of CFCs, aerosols now use hydrocarbons and compressed gases, such as nitrous oxide, as propellants. These chemicals are greenhouse gases and contribute to the global-warming effect. They also contain volatile organic compounds that release ozone into the lower atmosphere and add to smog.