Precious Ozone

Precious Ozone: 30th Anniversary of the Vienna Convention and International Ozone Day 2015

This year marks the 30th anniversary of the Vienna Convention for the Protection of the Ozone Layer, an important milestone in the protection of the ozone layer. The theme for the celebration of the anniversary and this year’s International Day for the Preservation of the Ozone Layer to be marked on 16 September is, “30 years of healing the ozone together.” The theme is supported by the slogan, “Ozone: All there is between you and UV.”    

The International Ozone Day is an annual event that commemorates the date of the signing, in 1987, of the Montreal Protocol on Substances that Deplete the Ozone Layer. In the last three decades, the Vienna Convention and its Montreal Protocol have galvanized 197 nations to work together on phasing out ozone-depleting substances, thus protecting the ozone layer for this and future generations and contributing significantly to global efforts to address climate change. 

As part of the commemorative activities, the Ozone Secretariat is conducting the “Precious Ozone” digital campaign to celebrate the many successes achieved under the ozone protection regime over the past 30 years and highlight the importance of the ozone layer in protecting life on Earth from the harmful effects of UV radiation.

The campaign’s products include a selection of visual images, animations and web-tools that help everyone from policymakers to children to better understand issues related to the ozone layer, such as what the ozone hole is like, where it is, how much ozone there is, or how deep the atmosphere is.

UN Secretary General's Message:  Arabic | Chinese | English | French | Russian | Spanish

Videos: Ozone Song | UNEP Executive Director's Message | Precious Ozone - The Size of it  

Ozone Map | 3D Ozone Map | Posters | Banners | Logo | Theme and Slogan Milestones | E-mail Signature | Activities & Material from Parties


The Ozone Song

As part of our digital campaign, we have created a song and animation showing phytoplankton celebrating the healing of the ozone hole. The song has been composed by David Haines, the ‘composer in residence’ at the MIT science festival since 2007. An animation has also been created so that children and adults around the world can join in the celebrations by learning and singing this song together.

Click on the image below to play the song.

Play the song teaser (chorus).

Phytoplankton are single-celled marine plants that support marine life in Antarctic coastal waters. They also moderate the global greenhouse effect by absorbing carbon dioxide from the atmosphere and releasing sulphur compounds to promote cloud formation. Depletion of stratospheric ozone over Antarctica during spring has increased solar ultraviolet radiation, causing a decline in phytoplankton concentration. But now that the ozone hole is healing, the phytoplankton can celebrate with their friends in the microbial community by singing this catchy tune!

Play the song with Spanish subtitles here

Click here to view and download an education pack for the song.

Click here to download the melody line music for the song.

Click here to download the sheet music with piano.

Watch a recording by performers of the song here.

UNEP Executive Director's Message

What is Ozone?

Ozone (O3) is a gas found in our atmosphere. Each ozone molecule is made up of three oxygen atoms. It is a pale blue gas with a distinctively pungent smell - and it is very scarce. Just 0.000004% of Earth’s total atmosphere is made up of ozone.

You have probably heard ozone spoken about within the context of ‘the ozone layer’. How much of a clear idea do you have about what and where this is?

Click here to download the video. 


What have we done about ozone depletion?

In the mid-1970s, we became aware that the ozone layer was being depleted. In the 1980s we decided to do something about it. On the strength of growing evidence suggesting that CFCs were contributing to stratospheric ozone depletion, scientists urged nations to control their use of CFCs, and so the Vienna Convention for the Protection of the Ozone Layer was adopted in 1985, followed by the Montreal Protocol on Substances that Deplete the Ozone Layer in 1987. States party to the Montreal Protocol agreed to phase out the use of ozone-depleting chemicals and have strengthened the Protocol over the years, leading to a 98% reduction of the historic baseline levels of the ozone-depleting substances produced and consumed globally.

The Montreal Protocol is widely lauded as a huge environmental success. Whilst the damage we have done to the ozone layer has not yet been undone, there is scientific evidence that the ozone layer is healing itself and is expected to recover by the middle of this century.

Click on the above screengrab to view a web interactive that celebrates the ratification of the Montreal Protocol by its parties.


The Ozone Map

Drag the map to explore the atmosphere! Turn elements of the map on and off using the buttons at the bottom. Each white spot represents 10 billion billion billion molecules of ozone.


What is the Ozone Layer?

The ozone layer is a layer in the Earth's atmosphere containing high concentrations of ozone. It is typically said to exist between about 20 and 30km above the Earth's surface, but it does not have definite edges.

You can see this on the ozone map. Each white spot represents 10 billion billion billion molecules of ozone, and they mostly sit within the middle reaches of the stratosphere.

The ozone layer protects us from harmful radiation from the sun. In particular, it protects us from UVB, which is a type of ultraviolet radiation. Small amounts of exposure to UVB can result in sunburn, but high levels of exposure would cause us - and most other life on earth - to die.

Perhaps you are wondering how it is that ozone is able to keep out UVB radiation. Ozone is an unstable and reactive gas. Because it is so reactive, the ozone in our atmosphere is very dynamic - it is being created and destroyed all the time. When UV light passes through the ozone layer, oxygen molecules are split up into their constituent oxygen atoms. These single atoms are then able to react with other oxygen molecules, forming ozone. This process is an endothermic reaction, meaning it needs to absorb energy (in this case the UV radiation) in order to occur. This also happens in reverse - because ozone is so unstable, each ozone molecule soon splits into an oxygen molecule and an oxygen atom. This is an exothermic reaction. This means that ozone splitting results in heat which causes an increase in atmospheric temperature.

This temperature increase is what makes the stratosphere (where most of the ozone is) a distinct atmospheric layer, and differentiates it from the troposphere and the mesosphere.

When undisturbed, the constant flux of ozone being both created and destroyed maintains a consistent ozone concentration in the stratosphere…

…However, this process is not undisturbed.


3d Ozone Map

This 3D map shows a 20 km x 20 km area of land and the air above it extending to an altitude of 100 km. Each floating particle represents 10 billion billion billion molecules of ozone. The area marked in orange indicates the ozone layer.

A little bit about atmospheric layers

The troposphere is the layer of the atmosphere closest to the earth. It extends from the ground to approximately 12km above sea level (though this varies with latitude and with the seasons). It contains around 75% of all the air in the atmosphere, and around 99% of water vapour. Most of the weather we experience (wind, clouds, rain) occurs in the troposphere too.

The troposphere is relatively hot at the bottom and gets cooler the higher you go. The stratosphere is relatively cold at the bottom and gets hotter the higher you go. The temperature difference between the troposphere and the stratosphere is caused by UV light passing through the ozone layer and triggering exothermic reactions. The point where the troposphere ends and the stratosphere begins (also known as the tropopause) is the altitude at which temperatures no longer decrease as height increases.

The air in the stratosphere is incredibly thin and very dry - humans would absolutely not be able to survive by breathing this air. In fact, the stratosphere contains the Armstrong Line. This line lies at 19km above sea level and represents the altitude at which atmospheric pressure is so low that water evaporates at body temperature. If a human were to exist above the Armstrong Line outside of a pressurised suit or aircraft, the saliva coating their tongue, throat and lungs would begin to boil. Above this limit, no amount of breathable oxygen delivered by any means will sustain human life for more than a few minutes.

When the stratosphere becomes the mesosphere, the temperature begins to decrease as altitude increases - much like it did in the troposphere. In fact, our atmospheric layers are entirely defined by these abrupt temperature changes.

We spend almost all our lives in the troposphere, but it might surprise you to hear that you may have been to the stratosphere without even realising it. Many commercial airliners choose to fly in the lower stratosphere to avoid the turbulence caused by clouds and convection currents in the troposphere below.

How have humans affected the Ozone layer?

Since the mid-1970s scientists have been concerned about the harmful effects of certain chlorofluorocarbons (CFCs) on the ozone layer. These CFC compounds are relatively inert and nontoxic, and humans found a use for them as cooling agents in refrigerators and air conditioning systems amongst other things. Because they are so inert, when CFCs become discharged into the atmosphere they diffuse and do not decompose straight away - not until they are hit by shortwave UV radiation. This occurs in the ozone layer.

When a CFC is hit by UV radiation, it loses its chlorine atom. This chlorine atom acts as a catalyst. It is able to steal one oxygen atom away from an ozone molecule, leaving an oxygen molecule and chlorine oxide. Chlorine oxide can then react with a single oxygen atom to form an oxygen molecule and a chlorine atom. This cycle means the chlorine atom is free to break up another ozone molecule.

One chlorine atom can destroy up to 100,000 ozone molecules before it is removed by some other reaction. This can devastating for the ozone layer. It disrupts the delicate flux and causes ozone to be destroyed faster than it is created.

Polar stratospheric clouds also catalyse ozone depletion by active chlorine.
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2015 International Ozone Day

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