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World Ozone Day celebrates 35 years of ozone layer protection

World Ozone Day, held every year on 16 September, in 2020 commemorates the 35th anniversary of the Vienna Convention for the Protection of the Ozone Layer.

The Vienna Convention was the first international treaty to address the depletion of the stratospheric ozone layer by halogenated chemicals, and the forerunner of the Montreal Protocol.

In 2020, the theme for World Ozone Day is “Ozone for life: 35 years of ozone layer protection,” signaling that “not only is ozone crucial for life on Earth, but that we must continue to protect the ozone layer for future generations,” according to the statements of United Nations Environment Programme on the website.

Moreover, celebrating World Ozone Day shows that collective decisions and action, guided by science, are the only way to solve major global crises according to UNEP. Further, in this year of the coronavirus pandemic that has brought such social and economic hardship, the ozone treaties’ message of working together in harmony and for the collective good is more important than ever.

In the mid-1970s, scientists, led by Nobel Prize winner Mario Molina, discovered that CFCs, then ubiquitous in HVAC&R applications, were damaging to the ozone layer, which filters out life-threatening ultraviolet radiation from the sun.

This realisation led to the adoption of the Vienna Convention. That treaty provided the framework needed to create the Montreal Protocol on Substances that Deplete the Ozone Layer, which was signed on 16 September, 1987.

Under the protocol, scientists, government and industry worked together to phase down CFCs and HCFCs to achieve a 99% reduction in ozone-depleting substances (ODSs).

The Montreal Protocol has been very successful, and the ozone layer is expected to return to pre-1980 values by the middle of the 21st century, according to the UN.

The Vienna Convention and the Montreal protocol also became the first international treaties in history to achieve universal ratification in 2009, something that also happened on 16 September.

Recognising the impact and importance of the treaties, the UN General Assembly then proclaimed 16 September the International Day for the Preservation of the Ozone Layer (World Ozone Day) in 1994.