Hydro-fluorocarbons (HFCs), HFCS
Hydrofluorocarbons (HFCs) are a group of compounds containing carbon, fluorine and hydrogen (unlike hydrochlorofluorocarbons (HCFCs), which also contain chlorine). They are generally colourless and odourless gases at environmental temperatures and for the most part chemically un-reactive.
HFCs are mainly used as substitutes for CFCs (Chlorofluorocarbons) and HCFCs (ozone depleting substances) that are being phased out under the 1987 Montreal Protocol. Major uses are as refrigerants in refrigeration and air conditioning equipment and as agents for plastic thermal insulation foams (e.g. for refrigerated vehicle insulation). Minor uses include Metered Dose Inhalers (e.g. for asthma), blowing one component foam (e.g. for building work) and use as a propellant for industrial and technical aerosols.
Major releases of HFCs are from leakage from refrigeration equipment during operation and its end of life destruction. Minor releases arise from the use of HFC containing aerosols and Metered Dose Inhalers. HFC 23 is also produced as a by-product in HCFC 22 manufacture. There are no natural sources of releases to the environment.
Excessive exposure to some hydrofluorocarbons may cause health effects on the brain and heart. The main environmental concern with HFCs is the role these compounds play as greenhouse gases, influencing climate change. Consequently they are controlled under the Kyoto Protocol. The concept of Global Warming Potential provides a common scale to compare the relative ability of different gases to trap heat in the atmosphere. HFCs have very high global warming potentials (100–1300 times that of carbon dioxide), however these are lower than the CFCs and HCFCs they replace. Due to their stability HFCs have fairly long atmospheric lifetimes (tens to hundreds of years).