CFC12s

CFC12s, also known as dichlorodifluoromethane, is a chlorofluorocarbon compound with the chemical formula CCl2F2. It is a colorless gas at room temperature and pressure, and it was widely used in various industrial and consumer applications throughout the mid-20th century. Its primary uses included refrigerants in air conditioning and refrigeration systems, propellants in aerosol cans, and blowing agents for foam insulation.

The chemical stability of CFC12s, which made them so useful, also contributed to their environmental persistence. When released into the atmosphere, CFC12s rise to the stratosphere. There, they are exposed to ultraviolet radiation from the sun, which causes them to break down and release chlorine atoms. These chlorine atoms then catalytically destroy ozone molecules, which form the Earth's protective ozone layer. The depletion of the ozone layer allows more harmful ultraviolet radiation to reach the Earth's surface, increasing the risk of skin cancer and other health problems, as well as damaging ecosystems.

Due to their significant impact on the ozone layer, the production and use of CFC12s were phased out globally under the Montreal Protocol on Substances that Deplete the Ozone Layer, an international treaty signed in 1987. While completely eliminating CFC12s from existing equipment is a complex challenge, their intentional release into the atmosphere has been largely stopped. Alternatives with lower environmental impact, such as hydrofluorocarbons (HFCs) and hydrofluoroolefins (HFOs), have replaced CFC12s in most applications. However, some HFCs are now being phased out due to their high global warming potential.