Three Facts about HFC-23 Your Doctor Should Know
1. In the atmosphere, HFC-23 is 14,800 times more effective in trapping heat than its CO2 equivalent.
2. HFC-23 persists in the atmosphere for about 300 years.
3. Emissions in 2006-2008 jumped 50 percent above the 1990-2000 average.
HFC-23, or trifluoromethane, is a byproduct of chlorodifluoromethane, or HCFC-22, a refrigerant used in heat-exchange appliances, air conditioners and refrigerators, and a base compound for manufacturing heat and chemical-resistant materials such as coatings and covering for cables, as well as aerosol propellants, solvents, fire fighting and foam blowing agents.
It is also heavily used in the semiconductor industry in plasma etching of silicon oxide and silicon nitride. Probably the most well known product associated with the release of HFC-23 to the atmosphere is Teflon, by DuPont.
Chlorodifluoromethane or difluoromonochloromethane is a hydrochlorofluorocarbon (HCFC) AKA, HCFC-22, or R-22.
Chlorodifluoromethane is prepared from chloroform: HCCl3 + 2 HF → HCF2Cl + 2 HCl
CHF3 also known as: HFC-23, R-23, Fluoroform, Carbon trifluoride, Methyl trifluoride, Fluoryl, Freon 23, Arcton 1, FE-13, UN 1984. CHF3 is produced as a by-product of polytetrafluoroethylene (PTFE) aka Teflon (DuPont). It is also generated biologically in trace amounts.
“Without the international effort to reduce emissions of HFC-23, its emissions and atmospheric abundance would have been even larger in recent years,” said Stephen Montzka, a NOAA research chemist. “As it was, emissions in 2006-2008 were about 50 percent above the 1990-2000 average.”
The finding comes in the face of worldwide efforts to prevent the gas release into the atmosphere. The Montreal Protocol stipulates the end of HCFC-22 production by 2020 in developed countries and 2030 in developing counties for those applications that allow CFC-22 released to the atmosphere.
Unfortunately, The Montreal Protocol imposes no restriction on the production of HCFC-22 from fluoropolymerization, which also co-produces the HFC-23. “The future atmospheric abundance of HFC-23 and its contribution to future climate change depends on amounts of HCFC-22 produced and the success of programs to reduce emissions of the co-generated HFC-23.”
“HFC-23 is one of the most potent greenhouse gases emitted as a result of human activities. Over a 100-year time span, one pound of HFC-23 released into the atmosphere traps heat 14,800 times more effectively than one pound of carbon dioxide. To date, the total accumulated emission of HFC-23 is small relative to other greenhouse gases, making this gas a minor (less than one percent) contributor to climate change at present.” NOAA Press Release said.
Scientists measured air collected from above the snow surface and down to 380 feet below the snow surface during field studies in Antarctica in 2001, 2005 and 2009. Using these results, they were able to determine how amounts of HFC-23 and other gases affecting climate and stratospheric ozone have changed in the recent past. The first published measurements of HFC-23 appeared in 1998 but this was the first time scientists examined how HFC-23 emissions have changed since 1996, particularly in developing nations and since the UNFCCC’s projects to reduce emissions began in 2003.
“Recent increases in global FHC-23 emission” by S.A. Montzka, L. Kuijpers, M.O.Battle, M. Aydin, K. Verhulst, E.S. Saltzman, D.W.Fahey will be published by January 29 in Geophysical Research Letters.