Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are halogenated paraffin hydrocarbons that contain only carbon (C), hydrogen (H), chlorine (Cl), and fluorine (F).
Chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are produced as volatile derivatives of methane, ethane, and propane.
CFCs and HCFCs are colorless, volatile, non-toxic liquids and gases with a faintly sweet ethereal odor.
CFCs and HCFCs at concentrations of 11% or more may cause dizziness, loss of concentration, central nervous system depression and/or cardiac arrhythmia.
Normal occupational exposure is rated at 0.07% and does not pose any serious health risks.
Commonly known as Freon.
Many CFCs used as refrigerants, propellants,and solvents.
Because CFCs contribute to ozone depletion in the upper atmosphere, they are being replaced with other products such as hydrofluorocarbons.
Billions of kilograms of chlorodifluoromethane are produced annually as a precursor to the monomer that is converted into Teflon.
CFCs were phased out via the Montreal Protocol due to their part in ozone depletion.
Because CO2 is close to saturation with high concentrations and few infrared absorption bands, its greenhouse effect has low sensitivity to changes in CO2 concentration, and the increase in temperature is roughly logarithmic.
Conversely, the low concentration of CFCs allow their effects to increase linearly with mass, so that chlorofluorocarbons are greenhouse gases with a much higher potential to enhance the greenhouse effect than CO2.
CFCs’ lack of reactivity gives them a lifespan that can exceed 100 years, allowing time to diffuse into the upper stratosphere.
In the stratosphere, the sun’s ultraviolet radiation is strong enough to cause CFC homolytic cleavage of the C-Cl bond.
In 1978, the EPA banned commercial manufacturing and use of CFCS and aerosol propellants.
By the year 2010, CFCs have been completely eliminated from developing countries as well.
The interim replacements for CFCs are hydrochlorofluorocarbons (HCFCs), which deplete stratospheric ozone, but to a much lesser extent than CFCs.
Ultimately, hydrofluorocarbons (HFCs) will replace HCFCs.
HFCs have an ozone depletion potential of 0.
Acceleration to elimination of hydrochlorofluorocarbons entirely by 2020 in a United Nations goal.
Hydrochlorofluorocarbons are less stable in the lower atmosphere, enabling them to break down before reaching the ozone layer.
A significant fraction of the HCFCs do break down in the stratosphere and contribute to chlorine buildup.
Natural refrigerant hydrocarbons have negligible environmental impacts and are also used worldwide in domestic and commercial refrigeration applications, and are becoming available in new split system air conditioners.
CFCs dissolve in seawater at the ocean surface and are transported into the deeper ocean.
Chlorofluorocarbons (CFCs) are anthropogenic compounds that have been released into the atmosphere since the 1930s in: air-conditioning, refrigeration, blowing agents in foams, insulations and packing materials, propellants in aerosol cans, and as solvents.
CFCs can be used as a tracer of ocean circulation.