The Montreal Protocol on Substances that Deplete the Ozone Layer

The Montreal Protocol on Substances that Deplete the Ozone Layer is a global agreement to protect the Earth’s ozone layer by phasing out the chemicals that deplete it. This phase-out plan includes both the production and consumption of ozone-depleting substances. The landmark agreement was signed in 1987 and entered into force in 1989.

The parties to the Protocol meet once a year to make decisions aimed at ensuring the successful implementation of the agreement. These include adjusting or amending the Protocol, which has been done six times since its creation. The most recent amendment, the Kigali Amendment, called for the phase-down of hydrofluorocarbons (HFCs) in 2016. These HFCs were used as replacements for a batch of ozone-depleting substances eliminated by the original Montreal Protocol. Although they do not deplete the ozone layer, they are known to be powerful greenhouse gases and, thus, contributors to climate change.

The Montreal Protocol provided a set of practical, actionable tasks that were universally agreed on. The Protocol has successfully met its objectives thus far and continues to safeguard the ozone layer today. Thanks to the collaborative effort of nations around the world, the ozone layer is well on its way to recovery.

Annex II: Approved destruction processes

  Applicability
  Concentrated sources Dilute sources
Technology Annex A, Gp. I

Annex B

Annex C, Gp. I

 Halon

(Annex A, Gp. II)

 Foam
Destruction and removal efficiency (DRE) 99.99% 99.99% 95%
Cement kilns Approved Not Approved  
Liquid injection incineration Approved Approved  
Gaseous/fume oxidation Approved Approved  
Municipal solid waste incineration     Approved
Reactor cracking Approved Not Approved  
Rotary kiln incineration Approved Approved Approved
Argon plasma arc Approved Approved  
Inductively coupled radio frequency plasma Approved Approved  
Microwave plasma Approved    
Nitrogen plasma arc Approved    
Gas phase catalytic dehalogenation Approved    
Superheated steam reactor Approved    

Notes: 1. The DRE criterion presents technology capability on which approval of the technology is based. It does not always reflect the day-to-day performance achieved, which in itself will be controlled by national minimum standards.

2. Concentrated sources refer to virgin, recovered and reclaimed ozone-depleting substances.

3. Dilute sources refer to ozone-depleting substances contained in a matrix of a solid, for example foam.