Editing Chlorofluorocarbon (section)

==History==

Prior to, and during the 1920s, refrigerators used toxic gases as refrigerants, including ammonia, sulphur dioxide, and chloromethane. Later in the 1920s after a series of fatal accidents involving the leaking of [[chloromethane]] from refrigerators, a major collaborative effort began between American corporations Frigidaire, General Motors, and DuPont to develop a safer, non-toxic alternative. [[Thomas Midgley Jr.]] of General Motors is credited for synthesizing the first chlorofluorocarbons. The Frigidaire corporation was issued the first patent, number 1,886,339, for the formula for CFCs on December 31, 1928. In a demonstration for the [[American Chemical Society]], Midgley flamboyantly demonstrated all these properties by inhaling a breath of the gas and using it to blow out a candle<ref name="Bellis">{{cite web | last=Bellis | first=Mary | title=Where Does Freon Come From? | website=ThoughtCo | date=12 August 2016 | url=https://www.thoughtco.com/history-of-freon-4072212 | access-date=11 April 2022}}</ref> in 1930.<ref name="Carlisle">{{cite book | last=Carlisle | first=Rodney | title=Scientific American inventions and discoveries : all the milestones in ingenuity—from the discovery of fire to the invention of the microwave oven | publisher=John Wiley & Sons | publication-place=Hoboken, N.J | year=2004 | isbn=0-471-24410-4 | oclc=53284995 | page=351}}</ref><ref name=McNeill>{{cite book | last=McNeill | first=J.R. | title=Something New Under the Sun: An Environmental History of the Twentieth-Century World (The Global Century Series) | publisher=W. W. Norton | year=2001 | isbn=978-0-393-32183-8 |page=421}} (as reviewed in {{cite journal |last1=Shmelev |first1=Stanislav |title=Something New Under the Sun: An Environmental History of the Twentieth-Century World, by J. R. McNeill (2001), New York: Norton. Reviewed by Michael Bess |journal=Journal of Political Ecology |date=December 2002 |volume=9 |issue=1 |doi=10.2458/v9i1.21636 |doi-access=free }}</ref>

By 1930, General Motors and Du Pont formed the Kinetic Chemical Company to produce Freon, and by 1935, over 8 million refrigerators utilizing R-12 were sold by Frigidaire and its competitors. In 1932, [[Carrier Global|Carrier]] began using R-11 in the worlds first self-contained home air conditioning unit known as the "atmospheric cabinet". As a result of CFCs being largely non-toxic, they quickly became the coolant of choice in large air-conditioning systems. Public health codes in cities were revised to designate chlorofluorocarbons as the only gases that could be used as refrigerants in public buildings.<ref>{{Cite web |last= |first= |title=NOAA Global Monitoring Laboratory - Halocarbons and other Atmospheric Trace Species |url=https://gml.noaa.gov/hats/publictn/elkins/cfcs.html#:~:text=CFCs%20were%20first%20synthesized%20in,in%20large%20commercial%20appilications1 |access-date=2023-12-12 |website=gml.noaa.gov |language=EN-US}}</ref>

Growth in CFCs continued over the following decades leading to peak annual sales of over 1 billion USD with greater than 1 million metric tonnes being produced annually. It wasn't until 1974 that it was first discovered by two University of California chemists, Professor F. Sherwood Rowland and Dr. Mario Molina, that the use of chlorofluorocarbons were causing a significant depletion in atmospheric ozone concentrations. This initiated the environmental effort which eventually resulted in the enactment of the Montreal Protocol.<ref>{{Cite web |title=Chlorofluorocarbons and Ozone Depletion |url=https://www.acs.org/education/whatischemistry/landmarks/cfcs-ozone.html |access-date=2023-12-12 |website=American Chemical Society |language=en}}</ref><ref>{{Cite web |title=Back from the brink: how the world rapidly sealed a deal to save the ozone layer |url=https://rapidtransition.org/stories/back-from-the-brink-how-the-world-rapidly-sealed-a-deal-to-save-the-ozone-layer/ |access-date=2023-12-12 |website=rapidtransition.org |language=en-GB}}</ref>

===Commercial development and use in fire extinguishing===
[[File:CFCs.svg|class=skin-invert-image|thumb|300px]]
During [[World War II]], various chloroalkanes were in standard use in military aircraft, although these early halons suffered from excessive toxicity. Nevertheless, after the war they slowly became more common in civil aviation as well. In the 1960s, fluoroalkanes and bromofluoroalkanes became available and were quickly recognized as being highly effective fire-fighting materials. Much early research with [[Bromotrifluoromethane|Halon 1301]] was conducted under the auspices of the US Armed Forces, while [[Bromochlorodifluoromethane|Halon 1211]] was, initially, mainly developed in the UK. By the late 1960s they were standard in many applications where water and dry-powder extinguishers posed a threat of damage to the protected property, including computer rooms, telecommunications switches, laboratories, museums and art collections. Beginning with [[warship]]s, in the 1970s, bromofluoroalkanes also progressively came to be associated with rapid knockdown of severe fires in confined spaces with minimal risk to personnel.

By the early 1980s, bromofluoroalkanes were in common use on aircraft, ships, and large vehicles as well as in computer facilities and galleries. However, concern was beginning to be expressed about the impact of chloroalkanes and bromoalkanes on the [[ozone layer]]. The [[Vienna Convention for the Protection of the Ozone Layer]] did not cover bromofluoroalkanes under the same restrictions, because emergency discharge of extinguishing systems was thought to be too small in volume to produce a significant impact and too important to human safety for restriction. Instead, the consumption of bromofluoroalkanes was frozen at 1986 levels.<ref>{{Cite web |title=Vienna Convention for the Protection of the Ozone Layer |url=https://legal.un.org/avl/ha/vcpol/vcpol.html |access-date=2023-12-12 |website=legal.un.org}}</ref>

===Regulation===
Since the late 1970s, the use of CFCs has been heavily regulated because of their destructive effects on the [[Ozone depletion|ozone layer]]. After the development of his [[electron capture detector]], [[James Lovelock]] was the first to detect the widespread presence of CFCs in the air, finding a [[mole fraction]] of 60 [[parts per trillion|ppt]] of CFC-11 over [[Ireland]]. In a self-funded research expedition ending in 1973, Lovelock went on to measure CFC-11 in both the Arctic and Antarctic, finding the presence of the gas in each of 50 air samples collected, and concluding that CFCs are not hazardous to the environment. The experiment did however provide the first useful data on the presence of CFCs in the atmosphere. The damage caused by CFCs was discovered by [[Sherry Rowland]] and [[Mario Molina]] who, after hearing a lecture on the subject of Lovelock's work, embarked on research resulting in the first publication suggesting the connection in 1974. It turns out that one of CFCs' most attractive features—their low reactivity—is key to their most destructive effects. CFCs' lack of reactivity gives them a lifespan that can exceed 100 years, giving them time to diffuse into the upper [[stratosphere]].<ref>{{cite journal|last1=Lee|first1=Bing-Sun|last2=Chiou|first2=Chung-Biau|title=The Relationship of Meteorological and Anthropogenic Factors to Time Series Measurements of CFC-11, CFC-12, and CH3CCl3 Concentrations in the Urban Atmosphere|journal=Atmospheric Environment|date=October 2008|volume=42|issue=33|page=7707|doi=10.1016/j.atmosenv.2008.05.042|bibcode=2008AtmEn..42.7706L}}</ref> Once in the stratosphere, the sun's [[ultraviolet]] radiation is strong enough to cause the [[homolysis (chemistry)|homolytic]] cleavage of the C-Cl bond. In 1976, under the Toxic Substances Control Act, the EPA banned commercial manufacturing and use of CFCs and aerosol propellants. This was later superseded in the 1990 amendments to the Clean Air Act to address stratospheric ozone depletion.<ref>{{cite report |last1=Auer |first1=Charles |first2=Frank |last2=Kover |first3=James |last3=Aidala |first4=Marks |last4=Greenwood |date=1 March 2016 |title=Toxic Substances: A Half Century of Progress |publisher=EPA Alumni Association |url=https://www.epaalumni.org/userdata/pdf/toxics.pdf }}</ref>

[[File:Future ozone layer concentrations.jpg|thumb|upright=1.20|alt=An animation showing colored representation of ozone distribution by year, above North America, through 6 steps. It starts with a lot of ozone especially over Alaska and by 2060 is almost all gone from north to south.|NASA projection of stratospheric ozone, in [[Dobson unit]]s, if chlorofluorocarbons had not been banned. [[:File:Future ozone layer concentrations.gif|Animated version]].]]

By 1987, in response to a dramatic seasonal depletion of the ozone layer over [[Antarctica]], diplomats in [[Montreal]] forged a treaty, the [[Montreal Protocol]], which called for drastic reductions in the production of CFCs. On 2 March 1989, 12 [[European Community]] nations agreed to ban the production of all CFCs by the end of the century. In 1990, diplomats met in [[London]] and voted to significantly strengthen the Montreal Protocol by calling for a complete elimination of CFCs by 2000. By 2010, CFCs should have been completely eliminated from developing countries as well.
[[File:Ozone cfc trends.png|class=skin-invert-image|left|thumb|upright=1.5|Ozone-depleting gas trends]]
Because the only CFCs available to countries adhering to the treaty is from recycling, their prices have increased considerably. A worldwide end to production should also terminate the smuggling of this material. However, there are current CFC smuggling issues, as recognized by the [[United Nations Environmental Programme]] (UNEP) in a 2006 report titled "Illegal Trade in Ozone Depleting Substances". UNEP estimates that between 16,000–38,000 tonnes of CFCs passed through the black market in the mid-1990s. The report estimated between 7,000 and 14,000 tonnes of CFCs are smuggled annually into developing countries. Asian countries are those with the most smuggling; as of 2007, China, India and South Korea were found to account for around 70% of global CFC production,<ref>{{cite book |title=Illegal Trade in Ozone Depleting Substances |date=2007 |publisher=[[United Nations Environmental Programme]] |isbn=978-92-807-2815-6 |url=http://www.mea-ren.org/files/publications/Illegal%20Trade%20in%20ODS.pdf |archive-url=https://web.archive.org/web/20120322071146/http://www.mea-ren.org/files/publications/Illegal%20Trade%20in%20ODS.pdf |archive-date=22 March 2012 }}{{pn|date=June 2024}}</ref> South Korea later to ban CFC production in 2010.<ref>{{cite news |title=S. Korea to ban import, production of freon, halon gases in 2010 |url=https://en.yna.co.kr/view/AEN20091222006700320 |work=Yonhap |date=23 December 2009 }}</ref> Possible reasons for continued CFC smuggling were also examined: the report noted that many of the refrigeration systems that were designed   to be operated utilizing the banned CFC products have long lifespans and continue to operate. The cost of replacing the equipment of these items is sometimes cheaper than outfitting them with a more ozone-friendly appliance. Additionally, CFC smuggling is not considered a significant issue, so the perceived penalties for smuggling are low. In 2018 public attention was drawn to the issue, that at an unknown place in east Asia an estimated amount of 13,000 metric tons annually of CFCs have been produced since about 2012 in violation of the protocol.<ref>{{cite news|title=Ozonkiller: Ein verbotener Stoff in der Atmosphäre – WELT|periodical=Welt.de|date=16 May 2018|url=https://www.welt.de/wissenschaft/article176426312/Ozonkiller-Ein-verbotener-Stoff-in-der-Atmosphaere.html|access-date=2018-05-18|language=de|archive-date=2020-10-05|archive-url=https://web.archive.org/web/20201005190707/https://www.welt.de/wissenschaft/article176426312/Ozonkiller-Ein-verbotener-Stoff-in-der-Atmosphaere.html/|url-status=live}}</ref><ref>{{cite web|title=Ozone hole-forming chemical emissions increasing and mysterious source in East Asia may be responsible|periodical=Independent.co.uk|date=16 May 2018|url=https://www.independent.co.uk/environment/ozone-hole-chemicals-cfc-increase-mystery-source-east-asia-antarctica-a8354481.html|access-date=2018-05-18|archive-date=2020-11-09|archive-url=https://web.archive.org/web/20201109025914/https://www.independent.co.uk/environment/ozone-hole-chemicals-cfc-increase-mystery-source-east-asia-antarctica-a8354481.html|url-status=live}}</ref> While the eventual phaseout of CFCs is likely, efforts are being taken to stem these current non-compliance problems.

By the time of the [[Montreal Protocol]], it was realised that deliberate and accidental discharges during system tests and maintenance accounted for substantially larger volumes than emergency discharges, and consequently halons were brought into the treaty, albeit with many exceptions.<ref>{{cite web | title=Halon essential use exemptions | website=DCCEEW | date=23 February 2023 | url=https://www.dcceew.gov.au/environment/protection/ozone/halon/essential-use-exeptions | access-date=17 May 2024}}</ref><ref>{{Cite web |title={{!}} Ozone Secretariat |url=https://ozone.unep.org/halon-aviation |access-date=2023-12-12 |website=ozone.unep.org}}</ref><ref>{{Cite web |title=Phase out of Halons : Firesafe.org.uk |url=https://www.firesafe.org.uk/phase-out-of-halons/ |access-date=2023-12-12 |website=www.firesafe.org.uk}}</ref>

====Regulatory gap====
While the production and consumption of CFCs are regulated under the Montreal Protocol, emissions from existing banks of CFCs are not regulated under the agreement. In 2002, there were an estimated 5,791 kilotons of CFCs in existing products such as refrigerators, air conditioners, aerosol cans and others.<ref>Campbell, Nick ''et al.'' [https://web.archive.org/web/20140923002205/http://www.ipcc.ch/pdf/special-reports/sroc/sroc11.pdf "HFCs and PFCs: Current and Future Supply, Demand and Emissions, plus Emissions of CFCs, HCFCs and Halons"], Ch. 11 in ''IPCC/TEAP Special Report: Safeguarding the Ozone Layer and the Global Climate System''</ref> Approximately one-third of these CFCs are projected to be emitted over the next decade{{when|date=March 2024}} if action is not taken, posing a threat to both the ozone layer and the climate.<ref>[http://www.eesi.org/100209_cfc Chlorofluorocarbons: An Overlooked Climate Threat, EESI Congressional Briefing]. {{webarchive|url=https://web.archive.org/web/20091204120541/http://www.eesi.org/100209_cfc |date=2009-12-04 }}. Eesi.org. Retrieved on 24 September 2011.</ref> A proportion of these CFCs can be safely captured and destroyed by means of high temperature, controlled incineration which destroys the CFC molecule.<ref>{{Cite web |last= |title=The cool way to destroy CFCs |url=https://www.newscientist.com/article/mg14920143-600-the-cool-way-to-destroy-cfcs/ |access-date=2023-12-12 |website=New Scientist |language=en-US}}</ref>

====Regulation and DuPont====
In 1978 the United States banned the use of CFCs such as Freon in aerosol cans, the beginning of a long series of regulatory actions against their use. The critical DuPont manufacturing patent for Freon ("Process for Fluorinating Halohydrocarbons", U.S. Patent #3258500) was set to expire in 1979. In conjunction with other industrial peers DuPont formed a lobbying group, the "Alliance for Responsible CFC Policy", to combat regulations of ozone-depleting compounds.<ref>{{cite book |last1=DeSombre |first1=Elizabeth R. |title=Domestic Sources of International Environmental Policy: Industry, Environmentalists, and U.S. Power |date=2000 |publisher=MIT Press |isbn=978-0-262-04179-9 |page=93 }}</ref> In 1986 DuPont, with new patents in hand, reversed its previous stance and publicly condemned CFCs.<ref name="Ethics">{{cite journal |last1=Smith |first1=Brigitte |title=Ethics of Du Pont's CFC Strategy 1975–1995 |journal=Journal of Business Ethics |date=1998 |volume=18 |issue=1 |pages=103–114 |doi=10.1023/A:1005789810145 }}</ref> DuPont representatives appeared before the [[Montreal Protocol]] urging that CFCs be banned worldwide and stated that their new HCFCs would meet the worldwide demand for refrigerants.<ref name="Ethics"/>

===Phasing-out of CFCs===<!-- don't change name, it is used as direct jump-address-->
Use of certain chloroalkanes as solvents for large scale application, such as dry cleaning, have been phased out, for example, by the [[Integrated Pollution Prevention and Control|IPPC]] directive on [[greenhouse gas]]es in 1994 and by the [[volatile organic compounds]] (VOC) directive of the [[European Union|EU]] in 1997. Permitted chlorofluoroalkane uses are medicinal only.

Bromofluoroalkanes have been largely phased out and the possession of equipment for their use is prohibited in some countries like the Netherlands and Belgium, from 1 January 2004, based on the [[Montreal Protocol]] and guidelines of the European Union.

Production of new stocks ceased in most (probably all) countries in 1994.<ref>{{cite web | url=https://www.epa.gov/ods-phaseout/phaseout-class-i-ozone-depleting-substances#:~:text=The%20ban%20on%20production%20and,several%20exemptions%20from%20the%20phaseout | title=Phaseout of Class I Ozone-Depleting Substances | date=22 July 2015 }}</ref><ref>{{Cite web |date=2021-04-01 |title=Ozone depleting substances |url=https://environment.govt.nz/acts-and-regulations/acts/ozone-layer-protection-act-1996/ozone-depleting-substances/ |access-date=2023-12-12 |website=Ministry for the Environment |language=en-GB}}</ref><ref>{{cite web|url=https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1144969/20230320_JSP_418_Leaflet_7.pdf|title=Management of Environmental Protection in Defence|website=service.gov.uk|access-date=17 May 2024}}</ref> However many countries still require aircraft to be fitted with halon fire suppression systems because no safe and completely satisfactory alternative has been discovered for this application. There are also a few other, highly specialized uses. These programs recycle halon through "halon banks" coordinated by the Halon Recycling Corporation<ref>[http://www.halon.org/ Welcome to the Halon Corporation]. {{webarchive|url=https://web.archive.org/web/20090919000942/http://www.halon.org/ |date=2009-09-19 }}. Halon.org. Retrieved on 24 September 2011.</ref> to ensure that discharge to the atmosphere occurs only in a genuine emergency and to conserve remaining stocks.

The interim replacements for CFCs are hydrochlorofluorocarbons (HCFCs), which deplete stratospheric ozone, but to a much lesser extent than CFCs.<ref name=prin>{{cite journal |last1=Prinn |first1=R. G. |last2=Weiss |first2=R. F. |last3=Fraser |first3=P. J. |last4=Simmonds |first4=P. G. |last5=Cunnold |first5=D. M. |last6=Alyea |first6=F. N. |last7=O'Doherty |first7=S. |last8=Salameh |first8=P. |last9=Miller |first9=B. R. |last10=Huang |first10=J. |last11=Wang |first11=R. H. J. |last12=Hartley |first12=D. E. |last13=Harth |first13=C. |last14=Steele |first14=L. P. |last15=Sturrock |first15=G. |last16=Midgley |first16=P. M. |last17=McCulloch |first17=A. |title=A history of chemically and radiatively important gases in air deduced from ALE/GAGE/AGAGE |journal=Journal of Geophysical Research: Atmospheres |date=27 July 2000 |volume=105 |issue=D14 |pages=17751–17792 |doi=10.1029/2000JD900141 |bibcode=2000JGR...10517751P |doi-access=free }}</ref> Ultimately, [[Haloalkanes#Hydro fluoro compounds (HFC)|hydrofluorocarbons (HFCs)]] will replace HCFCs. Unlike CFCs and HCFCs, HFCs have an ozone depletion potential (ODP) of 0.<ref>[http://www.epa.gov/ozone/defns.html "Ozone Layer Depletion", ''U.S. Environmental Protection Agency'']. {{webarchive|url=https://web.archive.org/web/20080919230641/http://www.epa.gov/ozone/defns.html |date=2008-09-19 }} accessed 25 June 2008</ref> DuPont began producing hydrofluorocarbons as alternatives to Freon in the 1980s. These included Suva refrigerants and Dymel propellants.<ref name="1930: Freon, DuPont Heritage">[http://www2.dupont.com/Heritage/en_US/1930_dupont/1930_freon/1930_freon_indepth.html Freon : 1930. In Depth]. {{webarchive|url=https://web.archive.org/web/20110319040544/http://www2.dupont.com/Heritage/en_US/1930_dupont/1930_freon/1930_freon_indepth.html |date=2011-03-19 }}. dupont.com (30 January 2009). Retrieved on 2011-09-24.</ref> Natural refrigerants are climate friendly solutions that are enjoying increasing support from large companies and governments interested in reducing global warming emissions from refrigeration and [[air conditioning]].

===Phasing-out of HFCs and HCFCs===
Hydrofluorocarbons are included in the [[Kyoto Protocol]] and are regulated under the [[Kigali Amendment]] to the [[Montreal Protocol]]<ref name="A Novel Tactic in Climate Fight Gains Some Traction, NY Times">{{cite news |url=https://www.nytimes.com/2010/11/09/science/earth/09montreal.html?ref=earth |title=A Novel Tactic in Climate Fight Gains Some Traction |author=Broder, John M. |date=9 November 2010 |page=A9 |newspaper=The New York Times |access-date=5 February 2013 |url-status=live |archive-url=https://web.archive.org/web/20130520114421/http://www.nytimes.com/2010/11/09/science/earth/09montreal.html?ref=earth |archive-date=20 May 2013 }}</ref> due to their very high [[Global Warming Potential|Global Warming Potential (GWP)]] and the recognition of halocarbon contributions to climate change.<ref>{{cite journal | last1 = Velders | first1 = G. J. M. | last2 = Andersen | first2 = S. O. | last3 = Daniel | first3 = J. S. | last4 = Fahey | first4 = D. W. | last5 = McFarland | first5 = M. | title = The importance of the Montreal Protocol in protecting climate | journal = Proceedings of the National Academy of Sciences | volume = 104 | issue = 12 | pages = 4814–9 | year = 2007 | pmid = 17360370 | doi = 10.1073/pnas.0610328104 | bibcode = 2007PNAS..104.4814V | pmc=1817831| doi-access = free }}</ref>

On September 21, 2007, approximately 200 countries agreed to accelerate the elimination of hydrochlorofluorocarbons entirely by 2020 in a [[United Nations]]-sponsored [[Montreal]] summit. Developing nations were given until 2030. Many nations, such as the [[United States]] and [[People's Republic of China|China]], who had previously [[Global warming controversy|resisted such efforts]], agreed with the accelerated phase out schedule.<ref>[http://www.epa.gov/ozone/title6/phaseout/hcfc.html HCFC Phaseout Schedule]. {{webarchive|url=https://web.archive.org/web/20090716164753/http://www.epa.gov/ozone/title6/phaseout/hcfc.html |date=2009-07-16 }}. Epa.gov (28 June 2006). Retrieved on 2011-09-24.</ref> India successfully achieved the complete phase out of HCFC-141 b in 2020.<ref>{{Cite web |title=India achieves complete phase out of one the most potent ozone depleting chemical |url=https://pib.gov.in/PressReleaseIframePage.aspx?PRID=1600233 |access-date=2022-06-02 |website=pib.gov.in}}</ref>

It was reported that levels of HCFCs in the atmosphere had started to fall in 2021 due to their phase out under the Montreal Protocol.<ref>{{cite journal |last1=Western |first1=Luke M. |last2=Daniel |first2=John S. |last3=Vollmer |first3=Martin K. |last4=Clingan |first4=Scott |last5=Crotwell |first5=Molly |last6=Fraser |first6=Paul J. |last7=Ganesan |first7=Anita L. |last8=Hall |first8=Brad |last9=Harth |first9=Christina M. |last10=Krummel |first10=Paul B. |last11=Mühle |first11=Jens |last12=O’Doherty |first12=Simon |last13=Salameh |first13=Peter K. |last14=Stanley |first14=Kieran M. |last15=Reimann |first15=Stefan |last16=Vimont |first16=Isaac |last17=Young |first17=Dickon |last18=Rigby |first18=Matt |last19=Weiss |first19=Ray F. |last20=Prinn |first20=Ronald G. |last21=Montzka |first21=Stephen A. |title=A decrease in radiative forcing and equivalent effective chlorine from hydrochlorofluorocarbons |journal=Nature Climate Change |date=11 June 2024 |volume=14 |issue=8 |pages=805–807 |doi=10.1038/s41558-024-02038-7 |doi-access=free }}</ref>

===Properly collecting, controlling, and destroying CFCs and HCFCs===
[[File:USEPA response to Hurricane Sandy with 45 freon tanks have been staged awaiting reclamation and recycling on 2 December 2012.jpg|thumb|336x336px|Freon tanks awaiting CFC reclamation and container recycling in 2012]]
While new production of these refrigerants has been banned, large volumes still exist in older systems and have been said to pose an immediate threat to our environment.<ref>{{Cite web |title=Emissions of several ozone-depleting chemicals are larger than expected |url=https://news.mit.edu/2020/emissions-ozone-cfc-chemicals-0317 |access-date=2022-10-18 |website=MIT News {{!}} Massachusetts Institute of Technology |date=17 March 2020 |language=en}}</ref> Preventing the release of these harmful refrigerants has been ranked as one of the single most effective actions we can take to mitigate catastrophic climate change.<ref>{{Cite web |date=2020-02-06 |title=Refrigerant Management @ProjectDrawdown #ClimateSolutions |url=https://www.drawdown.org/solutions/refrigerant-management |access-date=2022-10-18 |website=Project Drawdown |language=en}}</ref>

===Development of alternatives for CFCs===
Work on alternatives for chlorofluorocarbons in refrigerants began in the late 1970s after the first warnings of damage to [[stratosphere|stratospheric]] ozone were published.

The hydrochlorofluorocarbons (HCFCs) are less stable in the lower atmosphere, enabling them to break down before reaching the ozone layer. Nevertheless, a significant fraction of the HCFCs do break down in the [[stratosphere]] and they have contributed to more chlorine buildup there than originally predicted. Later alternatives lacking the chlorine, the hydrofluorocarbons (HFCs) have an even shorter lifetimes in the lower atmosphere.<ref name=prin/> One of these compounds, [[HFC-134a]], were used in place of CFC-12 in automobile air conditioners. Hydrocarbon refrigerants (a propane/isobutane blend) were also used extensively in mobile air conditioning systems in Australia, the US and many other countries, as they had excellent thermodynamic properties and performed particularly well in high ambient temperatures. [[1,1-Dichloro-1-fluoroethane]] (HCFC-141b) has replaced HFC-134a, due to its low ODP and GWP values. And according to the Montreal Protocol, HCFC-141b is supposed to be phased out completely and replaced with zero ODP substances such as [[cyclopentane]], HFOs, and HFC-345a before January 2020.<ref>[https://acp.copernicus.org/articles/22/9601/2022/acp-22-9601-2022.pdf acp.copernicus.org article] (PDF)</ref>

Among the natural refrigerants (along with ammonia and carbon dioxide), 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.<ref>[http://www.greenpeace.org/raw/content/china/en/campaigns/stop-climate-change/climate-friendly-cooling/cool-technologies-part-1.pdf "Greenpeace, Cool Technologies"]. {{webarchive|url=https://web.archive.org/web/20080706160041/http://www.greenpeace.org/raw/content/china/en/campaigns/stop-climate-change/climate-friendly-cooling/cool-technologies-part-1.pdf |date=2008-07-06 }}. (PDF). Retrieved on 24 September 2011.</ref>
Various other solvents and methods have replaced the use of CFCs in laboratory analytics.<ref>[http://www.norden.org/pub/ebook/2003-516.pdf Use of Ozone Depleting Substances in Laboratories. TemaNord 516/2003] {{webarchive |url=https://web.archive.org/web/20080227052412/http://www.norden.org/pub/ebook/2003-516.pdf |date=February 27, 2008 }}. Norden.org (1 January 2003). Retrieved on 2011-09-24.</ref>

In [[Metered-dose inhaler]]s (MDI), a non-ozone effecting substitute was developed as a propellant, known as "'''hydrofluoroalkane'''."<ref>{{cite journal |pmid=10743983|year=2000|last1=Boccuzzi|first1=S. J|title=Use of hydrofluoroalkane propellant delivery system for inhaled albuterol in patients receiving asthma medications|journal=Clinical Therapeutics|volume=22|issue=2|pages=237–47|last2=Wogen|first2=J|last3=Roehm|first3=J. B|doi=10.1016/S0149-2918(00)88482-9}}</ref>

{| border="1" cellspacing="0" cellpadding="0" style="margin:auto; margin:0; border-collapse:collapse; width:100%;"

!+ colspan="3" style="text-align:center; background:#ffdead;"| Applications and replacements for CFCs
|-
! style="text-align:center; background:#ffdead;"| Application
! style="text-align:center; background:#ffdead;"| Previously used CFC
! style="text-align:center; background:#ffdead;"| Replacement
|-
| Refrigeration & air-conditioning
| CFC-12 ({{chem2|CCl2F2}}); CFC-11 ({{chem2|CCl3F}}); CFC-13 ({{chem2|CClF3}}); HCFC-22 ({{chem2|CHClF2}}); CFC-113 ({{chem2|Cl2FCCClF2}}); CFC-114 ({{chem2|CClF2CClF2}}); CFC-115 ({{chem2|CF3CClF2}});
| [[HFC-23]] ({{chem2|CHF3}}); HFC-134a ({{chem2|CF3CFH2}}); HFC-507 [1:1 [[azeotrope]] of [[HFC-125]] ({{chem2|CF3CHF2}}) and HFC-143a ({{chem2|CF3CH3}})]; HFC-410 [1:1 azeotrope of HFC-32 ({{chem2|CF2H2}}) and HFC-125 ({{chem2|CF3CF2H}})]
|-
| Propellants in medicinal aerosols
| CFC-114 ({{chem2|CClF2CClF2}})
| [[HFC-134a]] ({{chem2|CF3CFH2}}); [[HFC-227ea]] ({{chem2|CF3CHFCF3}})
|-
| Blowing agents for foams
| CFC-11 ({{chem2|CCl3F}}); CFC 113 ({{chem2|Cl2FCCClF2}}); HCFC-141b ({{chem2|CCl2FCH3}})
| [[HFC-245fa]] ({{chem2|CF3CH2CHF2}}); HFC-365mfc ({{chem2|CF3CH2CF2CH3}})
|-
| Solvents, degreasing agents, cleaning agents
| CFC-11 ({{chem2|CCl3F}}); CFC-113 ({{chem2|CCl2FCClF2}})
| [[HCFC-225cb]] ({{chem2|C3HCl2F5}}) 
|}

===Development of Hydrofluoroolefins as alternatives to CFCs and HCFCs===
{{Main|Hydrofluoroolefins}}
The development of Hydrofluoroolefins (HFOs) as replacements for Hydrochlorofluorocarbons and Hydrofluorocarbons began after the Kigali amendment to the Montreal Protocol in 2016, which called for the phase out of high global warming potential (GWP) refrigerants and to replace them with other refrigerants with a lower GWP, closer to that of carbon dioxide.<ref>{{Cite journal |last=Rusch |first=George M. |date=2018 |title=The development of environmentally acceptable fluorocarbons |journal=Critical Reviews in Toxicology |volume=48 |issue=8 |pages=615–665 |doi=10.1080/10408444.2018.1504276 |pmid=30474464|s2cid=53745498 }}</ref> HFOs have an ozone depletion potential of 0.0, compared to the 1.0 of principal CFC-11, and a low GWP which make them environmentally safer alternatives to CFCs, HCFCs and HFCs.<ref>{{Cite web |title=The Environmental Benefits of HFOs |url=https://sustainability.honeywell.com/us/en/news-and-events/news/2020/06/the-environmental-benefits-of-hfos |access-date=2023-12-12 |website=sustainability.honeywell.com |language=en-US}}</ref><ref>{{Cite web |last=Dey |first=Anup Kumar |date=2023-07-11 |title=What are HFO Refrigerants? Their Benefits and Applications |url=https://whatispiping.com/hfo-refrigerants/ |access-date=2023-12-12 |website=What is Piping |language=en-us}}</ref>

Hydrofluoroolefins serve as functional replacements for applications where high GWP hydrofluorocarbons were once used. In April 2022, the EPA signed a pre-published final rule  Listing of HFO-1234yf under the Significant New Alternatives Policy (SNAP) Program for Motor Vehicle Air Conditioning in Nonroad Vehicles and Servicing Fittings for Small Refrigerant Cans. This ruling allows HFO-1234yf to take over in applications where ozone depleting CFCs such as R-12, and high GWP HFCs such as R-134a were once used.<ref>{{cite web | title=Association of Equipment Manufacturers | website=AEM | url=https://www.aem.org/not-found | access-date=17 May 2024}}</ref> The phaseout and replacement of CFCs and HFCs in the automotive industry will ultimately reduce the release of these gases to atmosphere and in turn have a positive contribution to the mitigation of climate change.<ref>{{Cite web |title=Automobile Air Conditioners and Chlorofluorocarbons (CFCs) |url=https://p2infohouse.org/ref/01/00038.htm |access-date=2023-12-12 |website=p2infohouse.org}}</ref><ref>{{Cite web |date=2022-08-09 |title=Phasing Down HFCs |url=https://www.nrdc.org/resources/phasing-down-hfcs |access-date=2023-12-12 |website=www.nrdc.org |language=en}}</ref>