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♤ They are emitted through a variety of industrial processes such as aluminum and semiconductor manufacturing & Substitution for Ozone-Depleting Substances.
♤ Many fluorinated gases have very high global warming potentials (GWPs) relative to other greenhouse gases. Fluorinated gases are well-mixed in the atmosphere, spreading around the world after they’re emitted.
♤ Fluorinated gases are removed from the atmosphere only when they are destroyed by sunlight in the far upper atmosphere. In general, fluorinated gases are the most potent and longest lasting type of greenhouse gases emitted by human activities.
♤ There are three main categories of fluorinated gases—
1. hydrofluorocarbons (HFCs),
2. perfluorocarbons (PFCs), and
3. sulfur hexafluoride (SF6).
Substitution for Ozone-Depleting Substances:
♤ Hydrofluorocarbons are used as refrigerants, aerosol propellants, solvents, and fire retardants. These chemicals were developed as a replacement for chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) because they do not deplete the stratospheric ozone layer.
♤ Unfortunately, HFCs are potent greenhouse gases with long atmospheric lifetimes and high GWPs, and they are released into the atmosphere through leaks, servicing, and disposal of equipment in which they are used.
Industry:
♤ Perfluorocarbons are compounds produced as a byproduct of various industrial processes associated with aluminum production and the manufacturing of semiconductors.
♤ Like HFCs, PFCs generally have long atmospheric lifetimes and high GWPs.
♤ Sulfur hexafluoride is used in magnesium processing and semiconductor manufacturing, as well as a tracer gas for leak detection. HFC-23 is produced as a by-product of HCFC-22 production.
Transmission and Distribution of Electricity:
♤ Sulfur hexafluoride is used in electrical transmission equipment, including circuit breakers.
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