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The Vienna Convention for the Protection of the Ozone Layer and the Montreal Protocol on Substances that Deplete the Ozone Layer logo was developed to provide a distinct brand for the two treaties across various communication assets and applications. The visual identity guideline is designed to provide a comprehensive overview of applications and correct use of the logo.

Primer for Members

This primer is intended to provide members of the Implementation Committee, especially new members, with a comprehensive understanding of the non-compliance procedure for the Montreal Protocol and the way in which the Committee has been operating since its establishment. In that regard, it is important to note that the non-compliance procedure adopted by the parties consists of only 16 paragraphs and that, like any entity, the Implementation Committee has developed a mode of efficient operation over time that, while firmly based on the non-compliance procedure, relies to a considerable extent on custom and precedent. For this reason, the primer refers to the requirements of the non-compliance procedure and, where necessary, explains the practice of the Committee, noting that such practice has evolved over time and will continue to do so. It is hoped that the primer will provide a basis for future advances in the timely and effective resolution of non-compliance cases while at the same time ensuring the consistent and transparent treatment of the issues by the Implementation Committee.

Cover page of A decrease in radiative forcing and equivalent effective chlorine from hydrochlorofluorocarbons

The Montreal Protocol and its successive amendments have been successful in curbing emissions of ozone-depleting substances and potent greenhouse gases via production/consumption controls. Here we show that the radiative forcing and equivalent effective chlorine from hydrochlorofluorocarbons has decreased from 61.75 mW m−2 and 321.69 ppt, respectively, since 2021, 5 years before the most recent projected decrease. This important milestone demonstrates the benefits of the Protocol for mitigating climate change and stratospheric ozone layer loss.

Climate Change and Ozone Layer Depletion Hotspots in the Food Cold Chain

Globally, food systems are responsible for approximately one-quarter of the world’s greenhouse gas (GHG) emissions, with the supply chain alone (which includes food processing, transport, packaging, and retail) contributing 18% to these emissions. The cold chain plays an important role in reducing food loss and waste (FLW), which accounts for approximately 6-8% of global emissions. However, the cold chains themselves can also significantly contribute to climate change and the depletion of the ozone layer. This is primarily due to the use of ozone-depleting substances (ODS) and greenhouse gases as refrigerants, and also emissions from the electricity necessary to operate the cold chain equipment.

Climate Change and Ozone Layer Depletion Hotspots in Air-conditioning Systems

Air-conditioning (A/C) systems have become essential in today’s life, providing space and comfort cooling. In 2021, the global demand for A/C reached nearly 111 million units with the majority used in residential (96 million units) and commercial sectors (14.5 million units). These systems use refrigerants that may still be ozone-depleting substances (ODS) and are also often potent greenhouse gases (GHG). Depending on the efficiency levels and usage patterns, the operation of A/C requires substantial amounts of electricity, contributing their indirect climate impacts. Increasing ambient temperatures in many regions, particularly in the last decade, have driven demand for space cooling provided by air conditioners.

Continuing benefits of the Montreal Protocol and protection of the stratospheric ozone layer for human health and the environment

The protection of Earth’s stratospheric ozone (O3) is an ongoing process under the auspices of the universally ratified Montreal Protocol and its Amendments and adjustments. A critical part of this process is the assessment of the environmental issues related to changes in O3. The United Nations Environment Programme’s Environmental Effects Assessment Panel provides annual scientific evaluations of some of the key issues arising in the recent collective knowledge base. This current update includes a comprehensive assessment of the incidence rates of skin cancer, cataract and other skin and eye diseases observed worldwide; the effects of UV radiation on tropospheric oxidants, and air and water quality; trends in breakdown products of fluorinated chemicals and recent information of their toxicity; and recent technological innovations of building materials for greater resistance to UV radiation. These issues span a wide range of topics, including both harmful and beneficial effects of exposure to UV radiation, and complex interactions with climate change. While the Montreal Protocol has succeeded in preventing large reductions in stratospheric O3, future changes may occur due to a number of natural and anthropogenic factors. Thus, frequent assessments of potential environmental impacts are essential to ensure that policies remain based on the best available scientific knowledge.


Veuillez trouver ci-joint l'invitation à la quarante-sixième réunion du Groupe de travail à composition non limitée des Parties au Protocole de Montréal relatif à des substances qui appauvrissent la couche d'ozone, qui se tiendra à Montréal du 8 au 12 juillet 2024.

En utilisant le lien exclusif fourni pour votre délégation, veuillez inscrire vos représentants aux réunion dès que possible.

Veuillez noter que Firefox et Chrome sont les navigateurs recommandés pour le système d'inscription. Le guide étape par étape du système est disponible ici. Le système contient déjà des informations sur les délégués qui ont assisté aux réunions précédentes du Protocole de Montréal. Veuillez mettre à jour les informations existantes si nécessaire. Pour les délégués qui n’ont pas assisté aux réunions précédentes, des informations devront être saisies. Veuillez vous assurer de fournir un courrier électronique valide pour chacun de vos représentants.


Secrétariat de l'ozone

Estimado Señor/Estimada Señora:

Se adjunta la invitación para la 46ª reunión del Grupo de Trabajo de composición abierta de las Partes en el Protocolo de Montreal sobre las Sustancias que Agotan la Capa de Ozono, que se celebrará en Montreal del 8 al 12 de julio de 2024.

Utilizando el enlace exclusivo que se proporciona para su delegación, registre a sus representantes en las reunión lo antes posible.

Tenga en cuenta que Firefox y Chrome son los navegadores recomendados para el sistema de registro. La guía paso a paso del sistema está disponible aquí. El sistema ya contiene información sobre los delegados que han asistido a reuniones anteriores del Protocolo de Montreal. Actualice la información existente según sea necesario. Para los delegados que no hayan asistido a reuniones anteriores, será necesario ingresar sus informaciones. Asegúrese de proporcionar una dirección de correo electrónico válida para cada uno de sus representantes.


Secretaría del Ozono

Abstract. We summarise current important and well-established open issues related to the depletion of stratospheric ozone and discuss some newly emerging challenges. The ozone layer is recovering from the effects of halogenated source gases due to the continued success of the Montreal Protocol despite recent renewed production of controlled substances and the impact of uncontrolled very short-lived substances. The increasing atmospheric concentrations of greenhouse gases, such as carbon dioxide, methane (CH4) and nitrous oxide (N2O), have large potential to perturb stratospheric ozone in different ways, but their future evolutions, and hence impacts, are uncertain.

Dear Sir/Madam,

Please find attached the invitation for the forty-sixth meeting of the Open-ended Working Group of the Parties to the Montreal Protocol on Substances that Deplete the Ozone Layer to be held in Montreal from 8 to 12 July 2024.

Using the exclusive link provided for your delegation, please register your representatives to the meeting as soon as possible.

Please note that Firefox and Chrome are the preferred browsers for the registration system. The step-by-step guide on the system is available here. The system already contains information on delegates who have attended previous Montreal Protocol meetings. Please update the existing information as necessary. Information will need to be entered for delegates who have not attended past meetings. Please ensure that you provide a valid email address for each of your representatives.

Yours sincerely,

Ozone Secretariat

Ref:  Oz.Sec/MOP35 Decisions                                                                                                    16 February 2024

Dear Sir/Madam,

The Ozone Secretariat is pleased to transmit, for your kind attention, a letter from the Executive Secretary, with regard to decisions XIV/7, XXXI/3, XXXIV/8 and XXXV/12 on cases of illegal trade in controlled substances and prevention of illegal production and consumption.

Yours sincerely, 

Ozone Secretariat  

UN Environment Programme
P.O. Box 30552 (00100)  
Nairobi, Kenya  
Telephone: +254 20 762 3611