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Ozone-Depleting Substances

This page provides information on compounds recognized as ozone-depleting substances (ODSHelpODSA compound that contributes to stratospheric ozone depletion. ODS include chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), halons, methyl bromide, carbon tetrachloride, hydrobromofluorocarbons, chlorobromomethane, and methyl chloroform. ODS are generally very stable in the troposphere and only degrade under intense ultraviolet light in the stratosphere. When they break down, they release chlorine or bromine atoms, which then deplete ozone. A detailed list (http://www.epa.gov/ozone/science/ods/index.html) of class I and class II substances with their ODPs, GWPs, and CAS numbers are available.) under the Montreal Protocol.

The ODS are split into two groups under the Clean Air Act: Class I ODS, such as chlorofluorocarbonsHelpchlorofluorocarbonsGases covered under the 1987 Montreal Protocol and used for refrigeration, air conditioning, packaging, insulation, solvents, or aerosol propellants. Since they are not destroyed in the lower atmosphere, CFCs drift into the upper atmosphere where, given suitable conditions, they break down ozone. These gases are being replaced by other compounds: hydrochlorofluorocarbons, an interim replacement for CFCs that are also covered under the Montreal Protocol, and hydrofluorocarbons, which are covered under the Kyoto Protocol. All these substances are also greenhouse gases. See hydrochlorofluorocarbons, hydrofluorocarbons, perfluorocarbons, ozone depleting substance. (CFCs), and Class II ODS, such as hydrochlorofluorocarbonsHelphydrochlorofluorocarbonsCompounds containing hydrogen, fluorine, chlorine, and carbon atoms. Although ozone depleting substances, they are less potent at destroying stratospheric ozone than chlorofluorocarbons (CFCs). They have been introduced as temporary replacements for CFCs and are also greenhouse gases. See ozone depleting substance. (HCFCs).

For each ODS, this page provides the compound’s atmospheric lifetime, Ozone Depletion PotentialHelpozone depletion potentialA number that refers to the amount of ozone depletion caused by a substance. The ODP is the ratio of the impact on ozone of a chemical compared to the impact of a similar mass of CFC-11. Thus, the ODP of CFC-11 is defined to be 1.0. Other CFCs and HCFCs have ODPs that range from 0.01 to 1.0. The halons have ODPs ranging up to 10. Carbon tetrachloride has an ODP of 1.2, and methyl chloroform's ODP is 0.11. HFCs have zero ODP because they do not contain chlorine. A table of all ozone-depleting substances (http://www.epa.gov/ozone/science/ods/index.html) shows their ODPs, GWPs, and CAS numbers. (ODP), Global Warming PotentialHelpGlobal Warming PotentialA number that refers to the amount of global warming caused by a substance. The GWP is the ratio of the warming caused by a substance to the warming caused by a similar mass of carbon dioxide. Thus, the GWP of CO2 is defined to be 1.0 . CFC-12 has a GWP of 8,500, while CFC-11 has a GWP of 5,000. Various HCFCs and HFCs have GWPs ranging from 93 to 12,100. Water, a substitute in numerous end-uses, has a GWP of 0. A table of all ozone-depleting substances (http://www.epa.gov/ozone/science/ods/index.html) shows their ODPs, GWPs, and CAS numbers, and another table shows the GWPs for many non-ozone-depleting substances (http://www.epa.gov/ozone/geninfo/gwps.html). (GWP), and Chemistry Abstract Service (CAS) registry numbers.

Information on acceptable ODS alternatives (e.g., hydrofluorocarbons) is available through EPA’s Significant New Alternatives Policy (SNAP) Program.

Class I ODS

Class I ODS are divided into eight groups.

  • Class I ODS listed in Groups 1 through 5 are identified in Title VI of the Clean Air Act.
  • Class I ODS listed in Groups 6 and 7,  methyl bromide and hydrobromofluorocarbons, are identified in EPA's Accelerated Phaseout final rule.
  • Class I ODS listed in Group 8, chlorobromomethane, is identified in EPA's Chlorobromomethane Phaseout final rule.
Chemical Name Lifetime, in years ODP1 (Montreal Protocol) ODP2 (WMO 2011) GWP1 (AR4) GWP2 (AR5) CAS Number
Group I
CFC-11 (CCl3F) Trichlorofluoromethane 45 1 1 4750 4660 75-69-4
CFC-12 (CCl2F2) Dichlorodifluoromethane 100 1 0.82 10900 10200 75-71-8
CFC-113 (C2F3Cl3) 1,1,2-Trichlorotrifluoroethane 85 0.8 0.85 6130 5820 76-13-1
CFC-114 (C2F4Cl2) Dichlorotetrafluoroethane 190 1 0.58 10000 8590 76-14-2
CFC-115 (C2F5Cl) Monochloropentafluoroethane 1020 0.6 0.5 7370 7670 76-15-3
Group II
Halon 1211 (CF2ClBr) Bromochlorodifluoromethane 16 3 7.9 1890 1750 353-59-3
Halon 1301 (CF3Br) Bromotrifluoromethane 65 10 15.9 7140 6290 75-63-8
Halon 2402 (C2F4Br2) Dibromotetrafluoroethane 20 6 13.0 1640 1470 124-73-2
Group III
CFC-13 (CF3Cl) Chlorotrifluoromethane 640 1 1 14420 13900 75-72-9
CFC-111 (C2FCl5) Pentachlorofluoroethane   1 1     354-56-3
CFC-112 (C2F2Cl4) Tetrachlorodifluoroethane   1 1     76-12-0
CFC-211 (C3FCl7) Heptachlorofluoropropane   1 1     422-78-6
CFC-212 (C3F2Cl6) Hexachlorodifluoropropane   1 1     3182-26-1
CFC-213 (C3F3Cl5) Pentachlorotrifluoropropane   1 1     2354-06-5
CFC-214 (C3F4Cl4) Tetrachlorotetrafluoropropane   1 1     29255-31-0
CFC-215 (C3F5Cl3) Trichloropentafluoropropane   1 1     4259-43-2
CFC-216 (C3F6Cl2) Dichlorohexafluoropropane   1 1     661-97-2
CFC-217 (C3F7Cl) Chloroheptafluoropropane   1 1     422-86-6
Group IV
CCl4 Carbon tetrachloride 26 1.1 0.82 1400 1730 56-23-5
Group V
Methyl Chloroform (C2H3Cl3) 1,1,1-trichloroethane 5 0.1 0.16 146 160 71-55-6
Group VI
Methyl Bromide (CH3Br) 0.8 0.7 0.66 5 2 74-83-9
Group VII
CHFBr2   1 1      
HBFC-12B1(CHF2Br)   0.74        
CH2FBr   0.73 0.73      
C2HFBr4   0.3-0.8 0.3-0.8      
C2HF2Br3   0.5-1.8 0.5-1.8      
C2HF3Br2   0.4–1.6 0.4–1.6      
C2HF4Br   0.7–1.2 0.7–1.2      
C2H2FBr3   0.1–1.1 0.1–1.1      
C2H2F2Br2   0.2–1.5 0.2–1.5      
C2H2F3Br   0.7–1.6 0.7–1.6      
C2H3FBr2   0.1–1.7 0.1–1.7      
C2H3F2Br   0.2–1.1 0.2–1.1      
C2H4FBr   0.07–0.1 0.07–0.1      
C3HFBr6   0.3–1.5 0.3–1.5      
C3HF2Br5   0.2–1.9 0.2–1.9      
C3HF3Br4   0.3–1.8 0.3–1.8      
C3HF4Br3   0.5–2.2 0.5–2.2      
C3HF5Br2   0.9–2.0 0.9–2.0      
C3HF6Br   0.7–3.3 0.7–3.3      
C3H2FBr5   0.1–1.9        
C3H2F2Br4   0.2–2.1 0.2–2.1      
C3H2F3Br3   0.2–5.6 0.2–5.6      
C3H2F4Br2   0.3–7.5 0.3–7.5      
C3H2F5Br   0.9–1.4 0.9–1.4      
C3H3FBr4   0.08­–1.9 0.08­–1.9      
C3H3F2Br3   0.1–3.1 0.1–3.1      
C3H3F3Br2   0.1–2.5 0.1–2.5      
C3H3F4Br   0.3–4.4 0.3–4.4      
C3H4FBr3   0.03–0.3 0.03–0.3      
C3H4F2Br2   0.1–1.0 0.1–1.0      
C3H4F3Br   0.07–0.8 0.07–0.8      
C3H5FBr2   0.04–0.4 0.04–0.4      
C3H5F2Br   0.07–0.8 0.07–0.8      
C3H6FBr   0.02–0.7 0.02–0.7      
Group VIII
CH2BrCl Chlorobromomethane 0.37 0.12 0.12      

Why are there multiple values given for the ODPs and GWPs?

The numbers in the “ODP1” column are from the Montreal Protocol. Some numbers have been updated as per amendments to the Protocol.

Data in the “ODP2” column come from WMO’s Scientific Assessment of Ozone Depletion: 2010.1 ODP values listed are semi-empirical and can be found in Table 5-1 of the document.

The numbers in the “GWP1” column represent global warming potentials over a 100-year time horizon. The numbers are from the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report: Climate Change 2007 (AR4).2 The values listed are for direct radiative forcing and can be found in Table 2.14 of the “Physical Science Basis” contribution to the report.

The numbers in the “GWP2” column also represent global warming potentials over a 100-year time horizon. The numbers are from the IPCC Fifth Assessment Report: Climate Change 2014 (AR5). The values listed are for direct radiative forcing and can be found in Table 8.A.1 of the “Physical Science Basis” contribution to the report.3

References

  1. WMO (World Meteorological Organization), 2011: Scientific Assessment of Ozone Depletion: 2010. Global Ozone Research and Monitoring Project—Report No. 52, Geneva, Switzerland, 516 pp.
  2. IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 996 pp.
  3. IPCC, 2013: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.

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Class II ODS

Chemical Name Lifetime, in years ODP1 (Montreal Protocol) ODP2 (WMO 2011) GWP1 (AR4) GWP2 (AR5) CAS Number
HCFC-21 (CHFCl2) Dichlorofluoromethane 1.7 0.04   151 148 75-43-4
HCFC-22 (CHF2Cl) Monochlorodifluoromethane 11.9 0.055 0.04 1810 1760 75-43-6
HCFC-31 (CH2FCl) Monochlorofluoromethane   0.02       593-70-4
HCFC-121 (C2HFCl4) Tetrachlorofluoroethane   0.01-0.04       354-14-3
HCFC-122 (C2HF2Cl3) Trichlorodifluoroethane   0.02-0.08     59 354-21-2
HCFC-123 (C2HF3Cl2) Dichlorotrifluoroethane 1.3 0.02 0.01 77 79 306-83-2
HCFC-124 (C2HF4Cl) Monochlorotetrafluoroethane 5.9 0.022       2837-89-0
HCFC-131 (C2H2FCl3) Trichlorofluoroethane   0.007–0.05       359-28-4
HCFC-132b (C2H2F2Cl2) Dichlorodifluoroethane   0.008–0.05       1649-08-7
HCFC-133a (C2H2F3Cl) Monochlorotrifluoroethane   0.02–0.06       75-88-7
HCFC-141b (C2H3FCl2) Dichlorofluoroethane 9.2 0.11 0.12 725 782 1717-00-6
HCFC-142b (C2H3F2Cl) Monochlorodifluoroethane 17.2 0.065 0.06 2310 1980 75-68-3
HCFC-221 (C3HFCl6) Hexachlorofluoropropane   0.015–0.07       422-26-4
HCFC-222 (C3HF2Cl5) Pentachlorodifluoropropane   0.01–0.09       422-49-1
HCFC-223 (C3HF3Cl4) Tetrachlorotrifluoropropane   0.01–0.08       422-52-6
HCFC-224 (C3HF4Cl3) Trichlorotetrafluoropropane   0.01–0.09       422-54-8
HCFC-225ca (C3HF5Cl2) Dichloropentafluoropropane 1.9 0.025 0.02 122 127 422-56-0
HCFC-225cb (C3HF5Cl2) Dichloropentafluoropropane 5.9 0.033 0.03 595 525 507-55-1
HCFC-226 (C3HF6Cl) Monochlorohexafluoropropane   0.02–0.1       431-87-8
HCFC-231 (C3H2FCl5) Pentachlorofluoropropane   0.05–0.09       421-94-3
HCFC-232 (C3H2F2Cl4) Tetrachlorodifluoropropane   0.008–0.1       460-89-9
HCFC-233 (C3H2F3Cl3) Trichlorotrifluoropropane   0.007–0.23       7125-84-0
HCFC-234 (C3H2F4Cl2) Dichlorotetrafluoropropane   0.01–0.28       425-94-5
HCFC-235 (C3H2F5Cl) Monochloropentafluoropropane   0.03–0.52       460-92-4
HCFC-241 (C3H3FCl4) Tetrachlorofluoropropane   0.004–0.09       666-27-3
HCFC-242 (C3H3F2Cl3) Trichlorodifluoropropane   0.005–0.13       460-63-9
HCFC-243 (C3H3F3Cl2) Dichlorotrifluoropropane   0.007–0.12       460-69-5
HCFC-244 (C3H3F4Cl) Monochlorotetrafluoropropane   0.009–0.14        
HCFC-251 (C3H4FCl3) Monochlorotetrafluoropropane   0.001–0.01       421-41-0
HCFC-252 (C3H4F2Cl2) Dichlorodifluoropropane   0.005–0.04       819-00-1
HCFC-253 (C3H4F3Cl) Monochlorotrifluoropropane   0.003–0.03       460-35-5
HCFC-261 (C3H5FCl2) Dichlorofluoropropane   0.002–0.02       420-97-3
HCFC-262 (C3H5F2Cl) Monochlorodifluoropropane   0.002–0.02       421-02-03
HCFC-271 (C3H6FCl) Monochlorofluoropropane   0.001–0.03       430-55-7

Why are there multiple values given for the ODPs and GWPs?

The numbers in the “ODP1” column are from the Montreal Protocol. Some numbers have been updated as per amendments to the Protocol.

Data in the “ODP2” column come from WMO’s Scientific Assessment of Ozone Depletion: 2010.1 ODP values listed are semi-empirical and can be found in Table 5-1 of the document.

The numbers in the “GWP1” column represent global warming potentials over a 100-year time horizon. The numbers are from the IPCC Fourth Assessment Report: Climate Change 2007 (AR4).2 The values listed are for direct radiative forcing and can be found in Table 2.14 of the “Physical Science Basis” contribution to the report.

The numbers in the “GWP2” column also represent global warming potentials over a 100-year time horizon. The numbers are from the IPCC Fifth Assessment Report: Climate Change 2014 (AR5). The values listed are for direct radiative forcing and can be found in Table 8.A.1 of the “Physical Science Basis: contribution to the report.3

References

  1. WMO (World Meteorological Organization), 2011: Scientific Assessment of Ozone Depletion: 2010. Global Ozone Research and Monitoring Project—Report No. 52, Geneva, Switzerland, 516 pp.
  2. IPCC, 2007: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M. Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 996 pp.
  3. IPCC, 2013: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp.

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