Chlorfluorierte

Chlorfluorierte, also known as chlorofluorocarbons (CFCs), are a class of organic compounds that contain carbon, chlorine, and fluorine atoms. They were widely used in the 20th century as refrigerants, propellants in aerosol sprays, blowing agents for foams, and solvents. CFCs are non-toxic, non-flammable, and chemically stable, which made them highly desirable for these applications.

However, their stability also proved to be their environmental downfall. Once released into the atmosphere, CFCs rise to the stratosphere. There, ultraviolet (UV) radiation from the sun breaks them down, releasing chlorine atoms. These chlorine atoms act as catalysts, initiating a chain reaction that destroys ozone molecules (O3). A single chlorine atom can destroy thousands of ozone molecules before being deactivated.

The depletion of the ozone layer has significant consequences for life on Earth. The ozone layer absorbs most of the sun's harmful UV-B radiation. A thinner ozone layer allows more UV-B radiation to reach the Earth's surface, leading to increased rates of skin cancer, cataracts, and damage to ecosystems, including crops and marine life.

Recognizing the severe threat posed by CFCs, the international community adopted the Montreal Protocol on Substances that Deplete the Ozone Layer in 1987. This landmark treaty phased out the production and consumption of CFCs and other ozone-depleting substances. As a result, the ozone layer is showing signs of recovery, though it will take many decades for it to return to pre-depletion levels. While CFCs are largely banned, their long atmospheric lifetime means they continue to contribute to ozone depletion for some time.