Today, September 16, marks the United Nations International Day for the Preservation of the Ozone Layer. The ozone layer, an atmospheric shield that sits in the stratosphere about 9 to 18 miles (15 to 30 kilometres) above the earth's surface, absorbs the sun's harmful ultraviolet rays. The depletion of the ozone layer has been a major concern for scientists and environmentalists, among others, after it was discovered in the 1970s that the ozone layer was being depleted. The first major steps to recognising the harmful effects of ozone layer depletion were taken 35 years ago, after the Vienna Convention for the Protection of the Ozone Layer which was adopted and signed by 28 countries in March 1985. This was followed by the drafting of the Montreal Protocol on Substances that Deplete the Ozone Layer in September 1987.

The Montreal Protocol, a multilateral environmental agreement, regulates the production and consumption of almost 100 man-made chemicals known as ozone depleting substances. Those chemicals, when released to the atmosphere, damage the stratospheric ozone layer that protects living beings and the environment on earth from harmful levels of ultraviolet radiation from the sun. The most well-known harm caused by UV radiation is an increased risk of skin cancer and cataracts, as well as damage to plants and marine ecosystems. The harmful impacts of UV radiation extend beyond the human world, as it also affects aquatic life, hinders plant growth and reduces agricultural productivity.

The years that followed the Montreal Protocol saw increased focus on phasing out chemicals with higher ozone depletion potentials including chlorofluorocarbons and halons. This was followed by the phasing out of hydrochlorofluorocarbons. With countries across the globe adhering to the phase-out schedules, the past 30 years have seen substantial progress in limiting damage to the ozone layer. The 2016 Kigali Amendment to the Montreal Protocol further aims to reduce the projected production and consumption of hydrofluorocarbons by more than 80 percent over the next 30 years. The phasing out of ozone depleting substances is considered a success story in terms of protecting humans and the environment through global collective action. Research has also shown that the hole in the ozone layer can actually be healed, and that its health has improved after the Montreal Protocol.

It is not for no reason that UN Secretary-General António Guterres called the Montreal Protocol a 'milestone for all people and our planet' as it has made positive impacts on human health, poverty eradication, climate change, and protecting the food chain. Guterres's statement rings true if we consider the claims by the United States Environmental Protection Agency that the country alone would see an additional 280 million cases of skin cancer, 1.5 million skin cancer deaths, and 45 million cataracts

The global collaboration that ensured the success of the Montreal Protocol should serve as a benchmark for dealing with the most pressing issues of the world today, including climate change, global warming, terrorism, environmental crisis, and even the Covid-19 pandemic that has shaken the economic and social foundations globally. It must serve as a reminder to states all over the world to yet again work in harmony for the collective good, and protect the world and humanity for future generations.