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7.3 Consumption of ozone-depleting substances

Modified on 2012/11/05 11:38 by MDG Wiki Handbook Categorized as Goal 7


Goal 7. Ensure environmental sustainability Target 7.A: Integrate the principles of sustainable development into country policies and programmes and reverse the loss of environmental resources


The consumption of ozone-depleting substances is the sum of the consumption of the ozone-depleting potential- weighted metric tons of all ozone-depleting substances controlled under the Montreal Protocol on Substances that Deplete the Ozone Layer.

Ozone-depleting potential-weighted metric tons are metric tons of individual ozone-depleting substances multiplied by their ozone-depleting potential.

Ozone-depleting substances (ODS) are defined in the Montreal Protocol as substances containing chlorine or bromine that destroy the stratospheric ozone layer which absorbs most of the biologically damaging ultraviolet radiation. The phasing out of ozone depleting substances, and their substitution by less harmful substances or new processes, are aimed at the recovery of the ozone layer. Substances controlled by the Montreal Protocol are categorised into annexes, with different groups in each annex. These include chlorofluorocarbons (CFCs) (Annex A, group I), halons (Annex A, group II), and methyl bromide (Annex E, group I) among others.

Controlled substances are substances in Annex A, Annex B, Annex C or Annex E of the Montreal Protocol, whether existing alone or in a mixture. They include the isomers of any such substance, but exclude any controlled substance or mixture that is in a manufactured product other than a container used for the transportation or storage of that substance. Therefore trade in finished products would not fall under the control of the Protocol.

Ozone depleting potential (ODP) refers to the amount of ozone depletion caused by a substance. It is the ratio of the impact on ozone of a chemical substance compared to the impact of a similar mass of CFC-11. The ODP of CFC-11 is defined to be 1. CFCs have ODPs that range from 0.6 to 1 while hydrochlorofluorocarbons (HCFCs) have ODPs that range from 0.001 to 0.52. Halons have ODPs of up to 10 while methyl bromide has an ODP of 0.6. A full list of the controlled substances as well as the control measures applicable to each group of substance can be found in the protocol text, which is available at http://ozone.unep.org/.

Method of computation
Consumption of ODS is calculated as the national production of ODS plus imports, minus exports, minus destroyed quantities, minus feedstock uses of a controlled substance.

Destruction and feedstock uses both remove ODS from the system, hence they are subtracted when calculating consumption. The Montreal Protocol also specifies that consumption shall not include the amounts used for quarantine and pre-shipment applications of methyl bromide, and further specifies that exports to non-Parties will count as consumption in the exporting Party.

The precise formula for calculating consumption is:

Consumption = (Total ODS Production) – (Destroyed ODS) – (Production for Internal Feedstock Use) – (Production for internal quarantine use (for methyl bromide only)) + (Total New Imports) – (Import for Feedstock) – (Import for Quarantine Use) – (Total New Exports) + (Exports to Non-parties)

Consumption of individual substances need to be multiplied by their ozone depleting potential and summed to calculate the consumption of all ODS in ozone-depleting potential weighted metric tons.


This indicator is used to monitor reduction in the usage of ODS that are controlled under the Montreal Protocol as these man-made substances have scientifically been shown to be solely responsible for ozone depletion. In particular, this indicator helps with the monitoring of the progress towards meeting commitments to phase out the use of ODS in countries that have ratified the 1987 Montreal Protocol on Substances that Deplete the Ozone Layer and its Amendments of London (1990), Copenhagen (1992), Montreal (1997) and Beijing (1999).

The Vienna Convention for the Protection of the Ozone Layer (1985) and the Montreal Protocol (1987) are now recognized as having been successful in preventing the global environmental catastrophe that might have occurred following the depletion of the stratospheric ozone. The Montreal Protocol aims to reduce and eventually eliminate emissions of anthropogenic ODS by ceasing their production and consumption. The phasing out of ODS and their replacement with less harmful substances or new processes are aimed at the recovery of the ozone layer.


Estimation of the consumption of ODS requires data on national ODS production plus imports, minus exports, minus stocks destroyed. These can be derived from national production and international trade statistics.

Data are usually collected and reported by the Ministry of Environment or by designated authorities such as an Environmental Protection Agency, Environment Management Authority, or National Ozone Unit. Countries collect the data using a variety of methods. These methods include securing consumption quantities from known producers and consumers, using estimates and surveys, and collecting information through (or from) customs agencies among other methods.


Consumption data can be disaggregated by sectors in which consumption or production of ODS takes place, and by substance. Such disaggregated data allow policymakers to identify sectors and substances that are more/less responsive than others to efforts to reduce ODS consumption and production.


For ozone depletion, this indicator does not reveal much about current trends in deterioration of the ozone layer because the ecosystem response to ODS consumption is delayed by up to several decades.

Another limitation for this indicator is that there are sometimes problems with the accuracy of the available consumption data. Sources of inaccuracies include errors of omission, under-reporting, over-reporting, and mis-categorisation where one substance is incorrectly reported as a different substance.

Availability of data for all substances varies across countries and years. In some cases, the consumption values for "All Ozone-Depleting Substances" refer only to those substances for which data were available in that year.


Not applicable for this indicator.


Data for this indicator at the international level are reported by the United Nations Environment Programme (UNEP) Ozone Secretariat. Countries that are Party to the Montreal Protocol report data annually to the Ozone Secretariat using data reporting formats agreed by the Parties. Parties not reporting when required are reminded by the Secretariat, and may also be subject to the non-compliance procedure of the Protocol once the deadline for reporting has passed.

Different countries have different methods of collecting the data, with varying degrees of accuracy. However, country data are not adjusted in any way and the reported numbers are used to calculate consumption of ODS in ozone-depleting potential metric tons.

Currently, the reported data are not validated by the UNEP Ozone Secretariat. However, inconsistencies in the data are checked and rectified in consultation with the countries. Starting with data for 2005, reported exports by Parties are communicated in aggregated form at the end of the year to Importing Parties to allow for cross-checking and verification.

Simple straight summation is used to derive global and regional estimates. Data are released on the Secretariat’s web site http://ozone.unep.org/ continuously and incrementally as different countries report their data.




UNITED NATIONS (1996). Glossary of Environmental Statistics. New York. Available from http://unstats.un.org/unsd/publication/SeriesF/SeriesF_67E.pdf.

UNITED NATIONS ENVIRONMENT PROGRAMME (2003). The Ozone Secretariat. Nairobi. Internet site http://ozone.unep.org/ or http://montreal-protocol.org

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