Freons

Freons, also known as chlorofluorocarbons (CFCs), are a class of organic compounds that were widely used as refrigerants, propellants in aerosol cans, and solvents. They are synthetic chemicals that were developed in the early 20th century due to their non-flammable, non-toxic, and stable properties. These characteristics made them ideal for various industrial and consumer applications.

The most common freons were derived from methane or ethane and contained chlorine, fluorine, and carbon atoms. Their chemical stability, while beneficial for their intended uses, also meant they persisted in the environment for a long time. This persistence led to significant environmental concerns.

In the late 20th century, scientific research revealed that freons were contributing to the depletion of the Earth's ozone layer. When released into the atmosphere, CFCs rise to the stratosphere, where ultraviolet radiation breaks them down, releasing chlorine atoms. These chlorine atoms then catalyze a chain reaction that destroys ozone molecules, which are crucial for absorbing harmful ultraviolet radiation from the sun.

The Montreal Protocol, an international treaty signed in 1987, was established to phase out the production and consumption of ozone-depleting substances, including freons. As a result, the use of freons has been dramatically reduced globally, and they have largely been replaced by alternative chemicals with lower environmental impact, such as hydrofluorocarbons (HFCs) and hydrofluoroolefins (HFOs). Although their production is heavily restricted, residual freons from older equipment can still be found.