Ozone Layer Depletion

Everyone says that the best way to protect yourself from the sun’s rays is to wear sunscreen. But nothing beats the best sunscreen of all – the ozone layer.

And best of all, no application is required.

Since its discovery, we constantly hear those in the science field tell us that it is being destroyed due to human activity. And unless we all do something about it, this ozone layer depletion will worsen. Here is everything you need to know about it. 

illustration of science

But suppose you have been regularly following the news. You may have heard the recent reports saying that the ozone layer hole is the smallest that it has ever been.

This is fantastic news that affects the entire world, but why should you be concerned about it?

To better understand why the depletion should be taken seriously, you must first grasp what is to know.

What is it, and Why is it Important?

You are probably aware that a shield is created to protect the one holding it from harm. However, other parts of the body are still vulnerable because the shield can only cover certain areas at a time.

The layer is like that, but it envelops the entire world. This protection is why this invisible layer is important to every living creature.

It consists of ozone molecules that are naturally occurring. This layer is called such because it contains the highest concentrations of ozone. That and oxygen are continuously formed as part of the ozone-oxygen cycle.

This continuous cycle is essential in preventing harmful radiation emitted by the sun from entering the Earth. This ultraviolet light is required in this cycle. It means that these molecules will absorb most of it, and what is left will pass through and reach Earth.

Without it, ultraviolet radiation can freely reach Earth without limits. And when it involves UV-B and especially UV-C, this will destroy not just the environment. Still, it will also cause deaths to living creatures in a short period.

blue sky

What Type of Rays are Filtered by it?

The sun produces large amounts of energy in different wavelengths. It is namely infrared radiation that we feel as heat and light that we see. Its ultraviolet radiation or UV rays cannot be seen or felt. Only the UV rays get filtered by the ozone layer among these three.

There are three different types of UV radiation, and they come with varying wavelengths:

  • UV-A has the longest wavelength, between 320 to 400 nanometers. It is not fully absorbed by this protective layer, which allows around 95% of it to reach the Earth’s surface. However, it is considered relatively harmless.
  • UV-B has a shorter wavelength, measuring between 290 to 320 nanometers. It is considered more harmful. While it can be absorbed, it can also pass through the depleted protective layer. The thinner it is, the more UV-B that can pass through and the greater its environmental and health effects. Sunburn is the most common effect.
  • UV-C is the most dangerous and comes with the shortest wavelength, only measuring between 100 to 290 nanometers. With the protective layer, UV-C rays are completely absorbed. It does not reach Earth, which is good because we do not have any natural defenses against this particular UV ray.

These UV rays can cause great damage, especially in large quantities. That is why this protection is vital to prevent overexposure to it.

What Does it Do?

You are already aware that it acts as a shield for the Earth, but what exactly does this layer do?

While preventing dangerous UV radiation from reaching Earth, it cannot completely block all UV rays. It makes it harder for the UV radiation to pass through it and only allows the weaker and less harmful ones to penetrate it.

Because of the ozone layer, the most harmful UV-C is absorbed by molecules present and is prevented from entering Earth.

It can be absorbed when it comes to UV-B, but these molecules will absorb not all UV-B. The amount of UV-B that passes through it will depend on the thickness of the layer itself.

On the other hand, most UV-A can pass through. Although considered the safest, UV-A can still pose harm if exposed to it in large amounts or for prolonged periods.

Where is it Located?

To know where it is located, you must first understand what is present above the Earth’s surface.

There are five main atmospheric layers present. Our main concern here is the stratosphere, the second layer from the Earth’s surface. While the two lowest layers both contain ozone, the stratosphere contains the largest amount of this molecule. This large concentration is what we call the ozone layer.

The stratosphere is the only well-equipped layer to handle these unstable molecules for longer periods. The stable or stratified layer lacks vertical convection, allowing the molecules to move up. It is not synonymous with the stratosphere since this layer is only confined in the lower region above the troposphere.

The stratosphere is roughly 10 km above the Earth’s surface and spans 50 km high. The ozone layer is only found about 20 to 30 km above the Earth. Unlike the stratosphere, the thickness of the ozone layer varies depending on the location and the season.

What is the Difference Between Bad and Good Ozone?

If we talk about ozone, most people think of it negatively. That it only causes harm and should be avoided. However, it is not always bad. Some are good, and it is important to understand their differences.

The good stuff is found in the stratosphere, specifically the protective layer. We have already mentioned this. The naturally-occurring layer is responsible for protecting us against harmful UV rays emitted by the sun. Because of this, it is important to take measures not to destroy it. The more of it present in this atmospheric layer, the better protected we are.

This is not the case for the bad stuff present in the troposphere. The stuff present here is due to pollutants coming from vehicle emissions and industrial facilities. It also comes from other sources that produce volatile organic compounds and nitrogen oxide that react with sunlight. This kind of ozone produced at the ground level forms what we know as smog, which is harmful to everyone.

Ground-level ozone is the bad stuff. It has various health effects if you get exposed to it, such as:

  • It may cause respiratory issues or exacerbate already existing conditions.
  • It may trigger eye irritation.
  • It may damage or kill plants.
  • It makes it difficult to breathe.
  • It may cause damage to lung tissue and cause scarring.
  • Increase susceptibility of plants to various stressors, such as diseases and pests
  • Agricultural yield reduction
diseased plant

Complicating matters is that the bad portion is insoluble in water, which means our bodies cannot process it. When the gas is ingested, it will simply pass through the lungs without being broken down. And because it is very reactive, it will immediately trigger various health issues and even cause death.

The difference between them clarifies why good ozone must be constantly replenished. Bad ozone must be eliminated, or at least limited. The latter is one of the main reasons for creating the Clean Air Act.

How is Good Stratospheric Ozone Formed?

The bad stuff is man-made in some way because it involves man-made processes. The stratospheric particles we consider good are formed naturally.

21% of the molecules found in the entire atmosphere are oxygen. This oxygen is crucial in forming ozone, together with ultraviolet radiation. The UV rays coming from the sun split up the oxygen molecules in the stratosphere to form two separate oxygen atoms. A newly single oxygen atom collides with an oxygen molecule. It will immediately react and combine to form the ozone molecule. This molecule has three oxygen atoms present, two from the existing oxygen molecule. The other one is the free oxygen atom.

Because the air is thinner, the higher it is in the atmosphere. The oxygen needed to create it is also fewer in number. On the other hand, UV light is necessary to decrease towards Earth. The stratosphere is the best location to form it because it balances the required UV light and oxygen molecules.

When Was the Hole Discovered?

Do you recall when the ozone layer hole was discovered, and everyone was alarmed by it? Everyone feared that it would immediately cause major damage to the whole world. It was a significant issue back then, but some people are still unclear why this discovery was monumental. Whether or not you already know why its discovery is crucial, it is important to correct any misconceptions.

It was believed to be just another gas found on Earth in the past. It was not until years later that scientists began to develop the idea that this gas is vital to the planet. It was unknown that it could absorb the UV rays coming from the sun. And in 1913, two French scientists named Charles Fabry and Henri Buisson discovered the actual presence of a layer abundant in ozone.

Another shocking discovery will be made decades later, spurring the entire world into action this time.

In 1984, a low ozone level was discovered in Syowa in Antarctica. It dropped to less than 200 Dobson Units. This contradicted the belief of scientists back then that levels tend to be steady. After all, records showed that these levels had remained the same for decades. However, this particular drop was not given much attention then. They believed that this finding was insignificant.

The following year was monumental. It was then confirmed by Joe Farman, Brian Gardiner, and Jonathan Shanklin that the level has indeed dropped in Antarctica and more than one station. It was initially thought of as incidents of malfunctioning equipment. They discovered that the levels started dropping beginning in 1979. It is especially during spring. The historical low was 220 Dobson Units. The level during that year was 194 Dobson Units and continued to decrease years later.

Unfortunately, the recorded level in 1985 was only 124. Not only that, the layer over the South Pole has dramatically decreased. Its thickness is only two-thirds of what it was several decades ago. This thinning in that area then became known as the Antarctic Ozone Hole.

The misconception about the newly discovered hole caused widespread alarm. The public believed that it was a literal hole that would allow the UV rays to reach Earth and cause harm to people freely. They believed it was especially for those who were directly underneath the hole.

This “hole” should not be taken literally, as there is no actual hole. What happens is that the amount present drops to less than 220 Dobson Units in a specific area. This mainly occurs in Antarctica and the Arctic region. The hole is referred to as the area of the layer that has less than that amount.

Scientists have discovered that this occurs seasonally, particularly during spring. Temperatures increase and more reactions occur in Antarctica. It affects the levels that will also affect the size of the hole.

What Causes The Depletion and the Hole?

Over the years, we have been told that certain chemicals cause depletion and create holes. However, most people do not fully understand this. It is largely owing to the confusion about what exactly the hole is. Since we have already clarified what this hole is, what happens next is what causes this phenomenon.

You may be wondering why it is typically associated with Antarctica. Aside from where the hole was discovered, this location also provides the ideal condition for ozone depletion.

The main culprit for this depletion is the CFCs or chlorofluorocarbons. Scientists discovered that these chemicals were widely used in aerosols and common household appliances. It’s like refrigerators and air conditioning units that use freon. It did not undergo any form of decay nor had any reaction with other chemicals in the troposphere, even for years. They remain stuck in the atmosphere. It is when these CFCs reach the stratosphere that they wreak havoc.

A specific type of cloud known as a nacreous cloud is one of the main causes of the holes. The nacreous cloud is also sometimes called ‘mother of pearl’ clouds. These clouds and ice crystals can only be formed in the layer and during wintertime when the temperature drops to -78 ℃ in the stratosphere. Prevalent in Antarctica, these conditions are ideal for surface chemistry to occur. The ice crystals present in these clouds draw CFCs closer to them.

When CFCs reach the stratosphere and react with UV radiation, it breaks apart these CFCs and releases various gases. The most dangerous of these is the highly reactive chlorine. A chlorine atom interacts with an ozone molecule. It destroys it by getting the third oxygen atom from it and producing the unstable chlorine monoxide molecule (ClO).

Once this new molecule meets a free oxygen atom, the oxygen atom part of the chlorine monoxide molecule will interact and form a new oxygen molecule. Because chlorine is now a free atom once more, it can again interact with another molecule and destroy it. This destruction occurs faster than the time it takes to replenish lost molecules. It causes depletion and increases the size of the hole.

Unfortunately, it is not just chlorine that can destroy these molecules. Bromine is also often released by CFCs and chlorine, as are other chemicals and compounds like hydrofluorocarbons and halons. Other chemicals released include:

  • methyl chloroform
  • hydrocarbons with bromine
  • and carbon tetrachloride

They are also known to cause ozone depletion.

With all these depleting substances, it is no wonder we were all caught off-guard when the hole was discovered. Then, it was already at an already considerable size.

What is Happening to the Hole?

Since its discovery, scientists have begun looking to understand what is happening to the hole. After 1985, they realized that the problem was more serious than they initially thought. This global problem has been the result of human activities over the years.

Using products and equipment that contain ozone-depleting substances was so widespread for decades. Nobody expected that it would greatly affect the layer in a matter of time. And as more research came, it became evident that the hole was bound to get bigger. That is unless the world does something about it. Worst of all, it can have fatal consequences in the future.

To stop this, world leaders decided to craft policies that would limit the depletion. The first one was the United Nations Vienna Convention for the Protection of the Ozone Layer, ratified in March 1985. The Vienna Convention was a landmark agreement because all countries involved in it also became signatories. They promoted the increase in research involving the ozone layer. It did not take an active stance regarding its protection.

The Montreal Protocol on Substances that Deplete the Ozone Layer, which was created in September 1987, is a different story. It supplemented the Vienna Convention by aiming to phase out the depleting substances. It was done in terms of both its manufacture and consumption. Like the Vienna Convention, the Montreal Protocol was also a landmark agreement because 196 countries ratified the agreement. It was adopted worldwide.

It initially aimed to cut down the production and use of CFCs and other substances that destroy the ozone layer in the entire world by 1999. Over the years, the Montreal Protocol has been revised many times. They eventually came up intending to ban these substances by 2000 completely. Some countries felt the urgency to start the ban years before the deadline.

Scientists know that it will take time to recover even with the protocol in place. Because these substances are stable, it means they remain in the atmosphere even after decades. Scientists do not expect them to be gone until around 2040 to 2070.

After all, record low levels were discovered in the mid-1990s when chlorine and bromine present in the atmosphere reached peak levels. And this is why it seems impossible for the hole to disappear in just a few years.

If you recall, we have received some very good news recently. The number of CFCs present in the atmosphere has constantly declined over the years after reaching record highs. The hole has also begun to show signs of being repaired. It has now led to the smallest hole since this hole was discovered. This is proof that the Montreal Protocol is effective.

While human activities caused the depletion, it is also a human intervention that is now fixing it.

How Does It Affect Human Health?

Depletion became a big deal for everyone because of its perceived impact on human health, especially misconceptions. Because the term ‘hole’ was used, the general public took it literally and believed that this hole would allow all the sun’s rays to get to Earth. They thought that since they already get bad sunburns now, how much worse would it be if it had a hole?

If more ozone molecules are being destroyed than replenished, severe sunburns are the least of your worries. You can look forward to the following health issues with the increased exposure to UV rays. It’s particularly to UV-B, brought about by depletion:

  • Skin cancer, including the non-melanoma kind
  • The development of melanoma is considered malignant
  • Cataracts often lead to blindness.
  • Snow blindness and other forms of photokeratitis
  • Damage to the cornea and retina. It can also cause damage to the conjunctiva and lens of the eyes.
  • Compromised immune system
  • Polymorphic Light Eruption
  • Eye diseases
  • Premature skin aging and other forms of skin damage
  • Pterygium
sun screen

You may have noticed that the health impacts brought about by depletion are limited to the skin and immune system. It has also been discovered that everyone can experience these health effects. Those who are fair-skinned are more vulnerable to the various skin conditions mentioned here. This is because darker-skinned people have more melanin, protecting against UV rays.

Many of these health issues have permanent effects. That is why it should be taken seriously. And if you are not yet aware, it can even have fatal consequences.

Remember all these when you go outside on a particularly hot day without slathering on some sunscreen.

What Impact Does It Have on Plant and Animal Life?

Think again if you believe that the impact of depletion is limited to humans. Sadly, plant and animal life are also vulnerable to the effects of too much exposure to UV radiation.


While certain plants are resistant to UV-B, many also have properties that protect them from radiation. Think of these plants having their version of the ozone layer and only allowing small amounts of radiation to pass through.

Despite these defenses, scientists have confirmed that plants can still be badly affected by 10% or higher depletion. If this happens, certain plants may experience the following negative effects:

  • Cell changes can result in irregularities in the pollination cycle and varying flowering times. It can also cause stunted plant growth.
  • Greater susceptibility to plant diseases
  • Imbalance in terms of plant and herbivore competition
  • Decrease in yield
  • Issues with photosynthesis
  • The decline of nitrogen-fixing bacteria

Note that plants have different reactions to UV-B. Even in large amounts, exposure to it will have an unequal impact on these plants. Some may be severely affected, while others may have little reaction. UV-B can also benefit some plants, but not if it gets overexposed. It is the case if the depletion continues.

turtle swimming in the ocean


Animals are also not spared from the harmful effects of UV-B overexposure due to depletion. Its effects on animals are quite similar to that on humans. It also mainly affects their eyes, skin, and immune system.

If it is depleted and they get overexposed to UV-B, animals may acquire the following:

Humans and animals seem to be more affected by this scenario than plants. Plants only recover during the months when the hole is smaller. This respite is crucial if plants are not given time to recover from too much UV-B exposure. It will happen if the ozone stops being replenished. It can drastically affect the food supply of both humans and animals alike.

Fortunately, we are likely to avoid this scenario because we are already reaping the benefits of the Montreal Protocol. With the banning of depleting substances, the hole is getting smaller. It reduces our chances of experiencing these impacts or at least experiencing them less severely.

We are one step further away from the worst-case scenario we were all afraid of.

2 Minute Summary:

There is more to fear about the depletion than getting extremely sunburned.

Scientists have proven that the size of the hole is detrimental to all living things here on Earth.

The bigger the hole present, the greater its negative impact.

We are all prime candidates to acquire various health issues with continuous depletion. It particularly involves our eyes and our immune system. It also affects our skin.

How does getting cataracts and becoming blind sound to you?

Or the acquisition of various illnesses because you have a weaker immune system?

But worst of all, we can also die from it because skin cancer is a very real possibility.

Not only that, but we can also die from starvation. Both plants and animals alike are also affected by it.

They can also die from it.

And when they die, our food source is affected.

One of the worst things you can do is underestimate the impact of the depletion.

Because if you do, you can get first-hand experience of its fatal consequences.


What are the effects of ozone layer depletion on the environment?

The Ozone layer is responsible for absorbing direct radiation from the sun. With ozone depletion, skin cancer rates would go up, and other diseases like cataracts would rise.

Is there still a hole in the ozone layer?

Although there was a hole in the ozone layer, it no longer exists. It had reached its maximum size on October 7th. But scientists were happy to report in December 2021 that it has finally closed.

What happens if the ozone layer is destroyed?

The ozone layer is essentially protecting us from harmful UVA and UVB radiation. Without it, human, animal, and plant DNA would be susceptible to damage. Skin cancer, immunodeficiency disorders, and other skin diseases would rise.

Why is the ozone layer so important?

The ozone layer protects us from harmful radiation. Not just humans but animals and plants would all fall prey to the deadly rays of UVA and UVB from the sun.

Leave a Comment

Your email address will not be published.