International Day for the Preservation of the Ozone Layer 2026

About International Day for the Preservation of the Ozone Layer

The International Day for the Preservation of the Ozone Layer, observed every year on September 16, marks the anniversary of the signing of the Montreal Protocol in 1987, the landmark treaty that phased out the chemicals eating a hole in Earth's protective ozone layer. Often shortened to World Ozone Day, it celebrates one of the rare environmental success stories in modern history.

The ozone layer is a shield of gas in the stratosphere that absorbs most of the sun's harmful ultraviolet radiation. By the 1980s, scientists discovered that chlorofluorocarbons and similar substances used in refrigerators, aerosols, and air conditioning were thinning it dramatically, especially over Antarctica.

The Montreal Protocol changed that trajectory. Nearly every country ratified it, industry retooled, and monitoring shows the ozone layer slowly healing, with recovery expected in the coming decades. The day uses that story to argue that global cooperation backed by science can solve even planetary-scale problems.

When is International Day for the Preservation of the Ozone Layer?

History of International Day for the Preservation of the Ozone Layer

Scientists first raised the alarm in 1974, when researchers showed that chlorofluorocarbons could destroy ozone in the stratosphere. Discovery of the Antarctic ozone hole in 1985 turned concern into urgency, and in September 1987 representatives from dozens of nations gathered in Montreal to sign the protocol limiting ozone-depleting substances. The treaty became the first universally ratified agreement in United Nations history and was later strengthened by amendments that accelerated phase-outs and added support for developing countries. The UN General Assembly designated September 16 as the Ozone Layer observance in 1994. Scientific assessments published every four years confirm that the layer is on track to recover, a result widely cited as proof that coordinated environmental policy works.

How to Celebrate International Day for the Preservation of the Ozone Layer

• ✦ Learn how the Montreal Protocol works and why scientists call it a model for climate action.
• ✦ Choose appliances and products labeled ozone-friendly or with low global warming potential.
• ✦ Repair or properly recycle old air conditioners and refrigerators so refrigerants are handled safely.
• ✦ Watch a documentary about the ozone hole and the scientists who found it.
• ✦ Teach kids about ultraviolet radiation and practice safe sun habits together.