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Ozone-depleting substances emitted through human activities cause large-scale damage to the stratospheric ozone layer, and influence global climate. Consequently, the production of many of these substances has been phased out; prominent examples are the chlorofluorocarbons (CFCs), and their intermediate replacements, the hydrochlorofluorocarbons (HCFCs).

This quadrennial Assessment was prepared by the Environmental Effects Assessment Panel (EEAP) for the Parties to the Montreal Protocol. The Assessment reports on key findings on environment and health since the last full Assessment of 2010, paying attention to the interactions between ozone depletion and climate change.

This report addresses the benefits of drawing down nitrous oxide (N2O) emissions. N2O is now the most significant ozone-depleting substance emission and the third most important greenhouse gas released into the atmosphere.

This third edition of the manual is updated to re ect the evolving role of Customs and enforcement officers in implementing their commitments under the Montreal Protocol. It includes additional information on all the substances now controlled under the Montreal Protocol, with a focus on hydrochlorofluorocarbons (HCFCs) which are primarily used as refrigerants and foam blowing agents. HCFCs replaced chlorofluorocarbons (CFCs) which were phased out by 1st January 2010. As most ozone depleting substances are also potent greenhouse gases, the section dealing with linkages between ozone layer depletion and global warming has been extended to include new scientific findings.

We use the Whole Atmosphere Community Climate Model, coupled to a deep ocean model, to investigate the impact of continued growth of halogenated ozone depleting substances (ODS) in the absence of the Montreal Protocol. We confirm the previously reported result that the growth of ODS leads to a global collapse of the ozone layer in mid-21st century, with column amounts falling to 100 DU or less at all latitudes. We also show that heterogeneous activation of chlorine in the lower stratosphere hastens this collapse but is not essential to produce it.

Many millions of patients with asthma and chronic obstructive pulmonary disease have safely switched from chlorofluorocarbon (CFC)-powered metered-dose inhalers (MDIs) to either hydrofluorocarbon (HFC) or DPIs. China will be the last country to phase out CFCs by 2016. HFCs are global warming gases which will be controlled in the near future. HFCs in MDIs may be phased out over the next 10–20 years.