CFC12

CFC-12, also known as R-12 or dichlorodifluoromethane (chemical formula CCl2F2), is a chlorofluorocarbon that has been widely used as a refrigerant in air conditioning and refrigeration systems since the mid-20th century. It is a colorless, nonflammable gas at room temperature with a boiling point of about −29.8 °C. It is relatively stable in the lower atmosphere but releases chlorine atoms when exposed to ultraviolet light in the stratosphere, contributing to ozone layer depletion.

Historically, CFC-12 was favored for its thermodynamic properties and stability, which enabled efficient cooling in automotive air conditioners, domestic and commercial refrigerators, and some industrial chillers. Because it is heavier than air and can accumulate in enclosed spaces, proper handling and recovery are important to minimize inhalation risks and environmental release. In normal exposure scenarios, CFC-12 is not highly toxic, but high concentrations can act as an asphyxiant.

Environmental and regulatory status is a central aspect of CFC-12’s history. It has a high ozone depletion potential and a long atmospheric lifetime, leading to its phase-out under the Montreal Protocol. Production and international trade have been severely restricted or prohibited in many regions since the 1990s, with remaining uses limited to servicing existing equipment and controlled through end-of-life recovery and recycling programs. As a result, alternatives such as HFCs and other refrigerants have largely supplanted CFC-12 in new equipment. Remediation emphasizes reclamation of existing stocks and safe disposal to prevent further emissions.