2.8 Ozone Depleting Substances and ODP

Ozone Depleting Substances

Ozone depleting substances (ODS) can be defined as a group of human-made compounds that have been scientifically proven to deplete the ozone layer and contribute to climate change.

Some of the major compounds classified as ODS include:

  •  Chlorofluorocarbons (CFCs)
  •  Bromofluorocarbons (halons)
  •  Methyl chloroform (1,1,1 trichloroethane)
  •  Carbon tetrachloride (CCl4)
  •  Methyl bromide (CH3Br)
  •  Hydrochlorofluorocarbons (HCFCs)

Ozone Depleting Potential (ODP)

Each ozone depleting substance differs in its capacity to destroy ozone molecules, which prompted scientists to adopt a system where each could be relatively compared.

The ODP of an ODS is characterized by the amount of calculated ozone column change as a result of emitting one unit of that gas into the atmosphere relative to the depletion that is caused by a reference gas (CFC-11: ODP 1.0).

This allows for different ODS to be compared to each other using a common unit.

For example, Halon 2402 (ODP 6.0) is six times more harmful to the ozone layer than CFC-11.