Page 227 - Materials Chemistry, Second Edition

10 Life Cycle Impact Assessment 213

stratosphere from man-made emissions of long-lived halocarbons and nitrous oxide
as used by most LCIA methods.
The midpoint indicator used without exception in all LCIA methods to calculate
characterisation factors is the Ozone Depletion Potential (ODP). In a similar manner
as the Global Warming Potential (GWP), it evaluates the potential of a chemical to
destroy the ozone layer based on a model from the World Meteorological
Organization (WMO 2014). The ODP essentially expresses the global reduction in
due to an ozone depleting substance i relative to
stratospheric O 3 concentration C O 3
due to 1 kg of CFC-11
the global reduction of stratospheric O 3 concentration C O 3
(CFCl 3 ), and is hence expressed in CFC-11 equivalents:
ðiÞ
DC O 3
ODP i ¼ ð10:5Þ
ðCFC 11Þ
DC O 3

10.7.3 Emissions and Main Sources

The halogen compounds in the stratosphere are mostly originating from very stable
industrial halocarbon gases used as solvents or refrigerants (the chlorinated CFCs or
freons), or fire extinguishers (the brominated halons). Groups of anthropogenic
ODS are: bromochloromethanes (BCM), CFCs, carbon tetrachloride, hydro-
bromofluorocarbons (HBFCs), hydrochlorofluorocarbons (HCFCs), tetra-
chloromethane, 1,1,1-trichloromethane, methyl bromide, methyl chloride and
halons. The main uses of ODS during the last century were: fire extinguishing
systems (halon), plastic foams, propellant gas in spray cans, fumigate and pesticides
(methyl bromide), metered-dose inhalers (MDIs), refrigeration and air-conditioning
and solvent degreasing.
Natural ozone depleting substances are CH 4 ,N 2 O, H 2 O and halogenated sub-
stances with sufficient stability and/or release rates to allow them to reach the
stratosphere. All ozone depleting substances have two common characteristics,
being:
• Chemically very stable in the lower atmosphere
• Capable of releasing chloride or bromide under UV radiation
(photodissociation)

The phasing-out of production and use of the concerned substances has been
successfully enforced under the Montreal protocol, which was signed in 1987 and
led to phasing-out of consumption and production of ODS by 1996 in developed
countries and by 2010 in developing countries. If continuously respected, this effort
should lead to the cessation of the annual appearance of the ‘ozone hole’ around
2070, the delay being due to the facts that (1) we are still emitting decreasing
amounts of relevant substances (mostly during the end-of-life treatment of old
refrigeration and air-conditioning systems) and (2) they are very persistent and may