Science Days: 16th of September

On the 16th of September, the world commemorates the International Day for the Preservation of the Ozone Layer, a day dedicated to raising awareness about the importance of the ozone layer and the global efforts to protect it. Established by the United Nations in 1994, this day marks the signing of the Montreal Protocol in 1987, a landmark international agreement aimed at phasing out substances that deplete the ozone layer.

Why is the ozone layer important?

The ozone layer, located in the Earth’s stratosphere, acts as a protective shield, absorbing the majority of the Sun’s harmful ultraviolet (UV) radiation. Without this layer:

• Increased UV exposure: Harmful UV rays would reach the Earth’s surface, leading to higher rates of skin cancer, cataracts, and other health problems.
• Environmental damage: Excessive UV radiation harms ecosystems, reduces crop yields, and affects aquatic life, particularly plankton, which form the base of the oceanic food chain.

The threat to the ozone layer

In the mid-20th century, scientists discovered that human-made chemicals, particularly chlorofluorocarbons (CFCs), were depleting the ozone layer. Used in refrigeration, air conditioning, aerosol sprays, and foam production, these substances release chlorine and bromine atoms when broken down in the stratosphere. These atoms destroy ozone molecules, creating a thinning of the ozone layer, famously known as the “ozone hole.”

The Montreal Protocol

Adopted on September 16, 1987, the Montreal Protocol on Substances that Deplete the Ozone Layer is one of the most successful environmental agreements in history. Its achievements include:

• Global cooperation: All 198 UN member states have ratified the protocol, making it the first treaty in UN history to achieve universal ratification.
• Phase-out of Ozone-depleting substances: The protocol has led to the phasing out of 99% of ozone-depleting substances, including CFCs, halons, and other harmful chemicals.
• Positive Impact: According to the UN, the ozone layer is on track to recover by the 2060s if current measures are maintained.

2025 Theme: From science to global action

The 2025 World Ozone Day theme, From Science to Global Action, highlights how scientific discovery about ozone depletion led to unprecedented international cooperation through the Vienna Convention and Montreal Protocol, proving that evidence-based policies can heal the planet. It underscores the need to keep translating science into effective action, phasing out harmful chemicals, implementing the Kigali Amendment, and maintaining global commitment, so the ozone layer continues to recover and future remains protected from harmful ultraviolet radiation.

Getting involved

1. Learn and share: Educate yourself and others about the ozone layer, its importance, and the measures taken to protect it.
2. Support eco-friendly products: Choose products that are labeled as ozone-friendly or free from harmful chemicals.
3. Advocate for action: Support policies and initiatives that promote environmental sustainability and the reduction of greenhouse gas emissions.
4. Celebrate progress: Acknowledge the success of international cooperation in preserving the ozone layer and use it as inspiration for tackling other global challenges.

A reminder for the future

The recovery of the ozone layer is a testament to what humanity can achieve through science, cooperation, and decisive action. However, the work is not done. Continued vigilance is necessary to prevent setbacks and address emerging threats, such as the illegal production of banned substances.

As you observe the International Day for the Preservation of the Ozone Layer, celebrate scientific progress while reaffirming human commitment to safeguarding the planet. By protecting the ozone layer, scientists are committed to protecting life itself.