Breakdown: World Ozone Day - Why the world celebrates it

Published: Sep. 15, 2021 at 11:04 AM CDT|Updated: Sep. 15, 2021 at 11:06 AM CDT
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MEMPHIS, Tenn. (WMC) - In 1970, when scientists first discovered the hole in the ozone layer, it was a matter of grave concern.

Scientists discovered that humanity was creating a hole in this protective shield, they raised the alarm. The hole – caused by ozone-depleting gases (ODSs) used in literally thousands of products in people’s daily lives around the world, such as refrigerators and air-conditioners – was threatening to increase cases of skin cancer and cataracts, and damage plants, crops, and ecosystems.

They raised the alarm and informed people on how to best reduce their carbon emissions which are the leading cause for harm to the ozone layer. With this in mind, the world’s governments banded together and formed the Vienna Convention in 1985. Under the convention, they established the Montreal Protocol which dictated that governments, scientists, and industries work together and cut out 99% of all ozone-depleting substances.

197 countries signed that treaty to phase out the use of the substances that harm or deplete the ozone layer, and is popularly considered the most successful international environmental treaty to date.

To commemorate the signing of the Montreal protocol, the United Nations General Assembly announced September 16 as ‘International Day for the Preservation of the Ozone Layer’ (AKA World Ozone Day) in 1994.


Simply put, life on Earth will not be possible without sunlight, but the energy emanating from the sun is too harmful for anything to survive, when in direct contact with it. The ozone layer is a stratospheric layer that acts as a shield for the earth, protecting it from the sun’s harmful ultraviolet radiation.

Earth’s atmosphere is made up of several layers. In order from lowest to highest, they are the Troposphere, the Ozone Layer, and the Stratosphere. While the ozone layer is often counted as its own distinct portion of the atmosphere, many scientists consider it to be a part of the Stratosphere. The area where we live is often called the biosphere because that is where most living things exist- but speaking in atmospheric terms, it is really intermingled with the Troposphere.

There are many features of our world that make the planet especially well suited to life on...
There are many features of our world that make the planet especially well suited to life on Earth. Our ideal distance from the Sun, the abundance of life-giving water, the plethora of nutritious materials and natural resources are among the most outstanding of these features. But we would be ill served to forget the Ozone Layer. This magnificent feature of our atmosphere is as necessary for life on Earth as it is strange and wonderful.(

The ozone layer is formed when oxygen molecules are broken apart by the ultra-violet (UV) rays of the sun in the stratosphere. The ozone layer is very important for the health and safety of all life on Earth because it protects us from harmful UV radiation. UV light is a band of the spectrum of light that is far outside of our ability to see. But despite the fact that we cannot see UV rays, they are extremely intense, can cause burns, and over time can cause damage to our skin which may lead to cancer.

The ozone layer protects us from 97% of the harmful effects of UV rays. Think about a time when you or someone you know spent too much time out in the sun and got a sunburn. Now think about the fact that those burns are just 3% of what they would have been if there was no ozone layer to filter out most of the UV rays.

The Ozone layer forms a natural shield that protects the Earth from the harmful UV rays of the sun, for which it gets the term “good ozone”.


There is also “bad ozone”, which harms animals, plants and human beings. Ozone at ground level is a harmful air pollutant, because of its effects on people and the environment, and it is the main ingredient in “smog.”

Tropospheric, or ground level ozone, is not emitted directly into the air, but is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC). This happens when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources chemically react in the presence of sunlight.

This can cause gaps or ‘holes’ in the layer, and allow harmful UV radiation from the sun to pass through the atmosphere without reflecting some of it away.

Near the Earth's surface, human activities lead to ozone concentrations several times higher...
Near the Earth's surface, human activities lead to ozone concentrations several times higher than the natural background level. Too much of this ground-level ozone is 'bad' as it is harmful to breathe and also damages vegetation.(EPA)

Ozone is most likely to reach unhealthy levels on hot sunny days in urban environments, but can still reach high levels during colder months. Ozone can also be transported long distances by wind, so even rural areas can experience high ozone levels.


Manmade chemicals containing halogens were determined to be the main cause of ozone loss. These chemicals are collectively known as ozone-depleting substances (ODSs). ODSs were used in literally thousands of products in people’s daily lives around the world.

The most important ODSs were chlorofluorocarbons (CFCs), which at one time were widely used in air conditioners, refrigerators, aerosol cans, and in inhalers used by asthma patients. Other chemicals, such as hydrochlorofluorocarbons (HCFCs), halons and methyl bromide also deplete the ozone layer.

This image shows ozone concentrations above Antarctica on Sept. 30, 2014.
This image shows ozone concentrations above Antarctica on Sept. 30, 2014.(NASA)

Most of our computers, electronics and parts of our appliances were cleaned with ozone-depleting solvents. Car dash boards, insulation foams in our houses and office buildings, water boilers and even shoe soles were made using CFCs or HCFCs. Offices, computer facilities, military bases, airplanes and ships extensively used halons for fire protection. A lot of the fruit and vegetables we ate were fumigated by methyl bromide to kill pests.

When a CFC molecule reaches the stratosphere, it eventually absorbs UV radiation, causing it to decompose and release its chlorine atoms. One chlorine atom can destroy up to 100,000 ozone molecules. Too many of these chlorine and bromine reactions disrupt the delicate chemical balance that maintains the ozone layer, causing ozone to be destroyed faster than it is created.

Since the 1990s, the size of the annual “ozone hole” that develops over the frigid South Pole has reduced progressively. Once a pressing environmental concern, the ozone hole depletion is one of the lesser environmental concerns today.

Every year on 16 September, the International Day for the Preservation of the Ozone Layer (AKA World Ozone Day) is celebrated across the globe.


  • Damage to human health and well-being
    • Skin cancers, eye diseases
  • Damage to food security
  • Damage to our environment
    • Just as uncontrolled ozone depletion threatens food production, it also threatens plants, animals and microbes in natural ecosystems.
  • Life on land
  • Life below water
  • Ecosystems
  • Damage to outdoor materials

Click here to learn more about what’s listed above.

While we still have work to do there is good news. As of now, 99 percent of the ozone-depleting substances that are controlled under the Montreal Protocol have been phased out. Scientists and researchers around the world continually monitor the ozone layer’s progress. They also measure ozone-depleting substances, including some that are not controlled under the Montreal Protocol. These substances have low concentrations in the atmosphere and don’t pose an immediate threat to the ozone layer.

Learn more about what you can do to help protect your family and the Ozone Layer.

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