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Ozone Depleting Chemicals

CFCs

The destruction of ozone is accelerated by certain trace gases containing nitrogen, hydrogen, bromine, and chlorine. These are referred to as ozone depletion chemicals.

Consumption of ozone depleting substances expressed as million tonnes of ozone depletion potential (ODP), 1989-2009.

ODP is a number that refers to the amount of ozone depletion caused by a chemical substance. Consumption of ozone depleting substances has largely been reduced in the past 20 years. Data source: GEO Data Portal, compiled from the UNEP Secretariat for the Vienna Convention and the Montreal Protocol (UNEP 2010)

 

The most commonly known ozone depletion chemicals (ODCs) are the CFCs or chlorofluorocarbons. Over the last 30 years man-made CFCs have been the main cause of stratospheric ozone depletion. 

CFCs however, are not the only ozone-depleting chemicals. Other ODCs include the methylhalides, carbon tetrachloride (CCl4), carbon tetrafluoride (CF4), and the halons which contain bromine instead of chlorine. Such compounds are called halocarbons.

Carbon tetrachloride (CCl4), despite its toxicity, was first used in the early 1900s as a fire extinguishing agent, and more recently as an industrial solvent, an agricultural fumigant, and in many other industrial processes including petrochemical refining, and pesticide and pharmaceuticals production. Recently it has also been used in the production of CFC-11 and CFC-12.

Methyl chloroform, also known as 1,1,1 trichloroethane is a versatile, all-purpose industrial solvent used primarily to clean metal and electronic parts. It was introduced in the 1950s as a substitute for carbon tetrachloride.

Halons, unlike CFCs, contain bromine, which also destroys ozone in the stratosphere. Halons are used primarily in fire extinguishers. Halon-1301 has an ozone depleting potential 10 times that of CFC-11. Although the use of halons in developed countries has been phased out since 1996, the atmospheric concentration of these potent, ozone destroyers is still rising because of their long atmospheric lifetimes.

Methyl bromide, another bromine-containing halocarbon, has been used as a pesticide since the 1960s.

Class I and Class II Ozone Depleting Substances

 

Class I Ozone Depleting Substances

Halocarbon Number Molecular Formula Name
CFC-11 CCl3F Trichlorofluoromethane
CFC-12 CCl2F2 Dichlorodifluoromethane
CFC-113  C2Cl3F3 Trichlorotrifluoroethane
CFC-114 C2Cl2F4 Dichlorotetrafluoroethane
CFC-115 C2ClF5 Chloropentafluoroethane
Halon 1011 CH2BrCl Bromochloromethane
Halon 1202 CBr2F2 Dibromodifluoromethane
Halon 1211 CF2ClBr Bromochlorodifluoromethane
Halon 1301 CF3Br Bromotrifluoromethane
Halon 2402 C2F4Br2 Dibromotetrafluoroethane
CFC-13 CClF3 Chlorotrifluoromethane
CFC-111 C2Cl5F Pentachlorofluoroethane
CFC-112 C2Cl4F2 Tetrachlorodifluoroethane
CFC-211 C3Cl7F3 Heptachlorofluoropropane
CFC-212 C3Cl6F2 Hexachlorodifluoropropane
CFC-213 C3Cl5F3 Pentachlorotrifluoropropane
CFC-214 C3Cl4F4 Tetrachlorotetrafluoropropane
CFC-215 C3Cl3F5 Trichloropentafluoropropane
CFC-216 C3Cl2F6 Dichlorohexafluoropropane
CFC-217 C3ClF7 Chloroheptafluoropropane
Carbon Tetrachloride CCl4 Tetrachloromethane
Methyl Chloroform

CHCl3

Trichloroethane (1,1,1 Trichloroethane only)
Methyl Bromide

CH3Br

Bromomethane, monobromomethane

Class II Ozone Depleting Substances

HCFC Number Molecular Formula   HCFC Number Molecular Formula
HCFC-21

CHFCl2

  HCFC-224

C3HF4Cl3

HCFC-22

CHF2Cl

  HCFC-225

C3HF5Cl2

HCFC-31

CH2FCl

  HCFC-225ca

CF3CF2CHCl2

HCFC-121

C2HFCl4

  HCFC-225cb

CF2ClCF2CHClF

HCFC-122

C2HF2Cl3

  HCFC-226

C3HF6Cl

HCFC-123

C2HF3Cl2

  HCFC-231

C3H2Cl5

HCFC-123b

CHCl2CF3

  HCFC-232

C3H2F2Cl4

HCFC-124

C2HF4Cl

  HCFC-233

C3H2F3Cl3

HCFC-124b

CHFClCF3

  HCFC-234

C3H2F4Cl2

HCFC-131

C2H2FCl3

  HCFC-235

C3H2F5Cl

HCFC-132

C2H2F2Cl2

  HCFC-241

C3H3FCl4

HCFC-133

C2H2F3Cl

  HCFC-242

C3H3F2Cl3

HCFC-141

C2H3FCl2

  HCFC-243

C3H3F3Cl2

HCFC-141b

CH3CFCl2

  HCFC-244

C3H3F4Cl

HCFC-142

C2H3F2Cl

  HCFC-251

C3H4FCl3

HCFC-142b

CH3CF2Cl

  HCFC-252

C3H4F2Cl2

HCFC-151

C2H4FCl

  HCFC-253

C3H4F3Cl

HCFC-221

C3HFCl6

  HCFC-261

C3H5FCl2

HCFC-222

C3HF2Cl5

  HCFC-262

C3H5F2Cl

HCFC-223

C3HF3Cl4

  HCFC-271

C3H6FCl