What Will Replace CFCs

Aerosols Crc-11,CF(T12 hydrocarbons, HFC-152a, dimethyl ether and water, pumps, roll-ons 

Cleaning solvents CFC-113, CH3CCI3 water-based processes other 

Fire extinguishers Halon-1301, CFjI and other possibilities 

X Supercritical COg is above the critical temperature (T ), where gas and liquid coexist with no 

CFCs in aerosol cans and blown foams have been replaced by a variety of compounds such as propane, butane, HCFCs, and HFGs. Most commercial products now routinely advertise that they contain no CFCs, but most fail to acknowledge that the replacement compounds still may cause ozone depletion and global warming. The search for safe and effective alternatives to CFCs continues. Maybe new technology will come to the rescue soon. 

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Because of the environmental problems associated with CFCs, steps have been taken to limit their manufacture and use. A major step was the signing in 1987 of the Montreal Protocol on Substances That Deplete the Ozone Layer, in which participating nations agreed to reduce CFC production. More stringent limits were set in 1992, when representatives of approximately 100 nations agreed to ban the production and use of CFCs by 1996, with some exceptions for essential uses. Since then, the production of CFCs has indeed dropped precipitously, and the size of the ozone hole has leveled off. Nevertheless, because CFCs are unreactive and because they diffuse so slowly into the stratosphere, scientists estimate that ozone depletion will continue for many years to come. What substances have replaced CFCs At this time, the main alternatives are hydrofluorocarbons, compounds in which C — H bonds replace the C—Cl bonds of CFCs. One such compound in current use is CH2FCF3, known as HFC-134a. 

Baker Norton has launched another solution HFA-134a BDP preparation in certain countries, which is recommended as a direct microgram-for-micro-gram replacement for CFC-BDP (89). This is surprising, as the particle size and dose delivered from this preparation is similar to that of the 3M HFA preparation described above. Serum cortisol levels taken at 9 a.m. were compared following very large doses of BDP-CFC or BDP-HFA 500 pg for 12 weeks. No statistical difference was found. It is likely that prescribing different doses of what appear to be similar HFA-BDP solutions will cause confusion. 

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