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 required.

Since its discovery, we constantly hear those in the science field tell us that the ozone layer is being destroyed due to human activity. And unless we all do something about it, this ozone layer depletion is bound to get worse.

But if 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 incredible news that affects the entire world, but why exactly should you be concerned about it?

To better understand why ozone layer depletion should be taken seriously and why we need to keep taking measures to replenish it, you must first get a good grasp of the concepts involving the ozone layer.

What is the Ozone Layer 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 ozone layer is like that, but it envelops the entire world. This protection is the main reason why this invisible layer is important to every living creature.

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

This cycle that continuously occurs in the ozone layer is essential in the prevention of harmful radiation emitted by the sun from entering the Earth. This ultraviolet light is required in this cycle, which means that most of it will be absorbed by these molecules and what is left will pass through the ozone layer and reach Earth.

Without the ozone layer, 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, but it will also cause deaths to living creatures in a short period of time.

What Type of Rays are Filtered by the Ozone Layer?

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

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, and is not fully absorbed by the ozone layer, which allows around 95% of it to reach Earth’s surface. However, it is considered relatively harmless.
  • UV-B has a shorter wavelength, measuring between 290 to 320 nanometers, and is considered more harmful. While it can be absorbed, it can also pass through the ozone layer if it is depleted; the thinner the ozone layer, the more UV-B that can pass through and the greater its environmental and health effects, with sunburn being the most common effect.
  • UV-C is the most dangerous of all and comes with the shortest wavelength, only measuring between 100 to 290 nanometers. The ozone layer completely absorbs UV-C rays that is why it does not reach Earth, which is a good thing 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 the presence of the ozone layer is vital to prevent overexposure to it.

What Does the Ozone Layer Do?

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

While it prevents dangerous UV radiation from reaching Earth, it is not capable of completely blocking all UV rays. What it does is to make it harder for the UV radiation to pass through it, and only allowing the weaker and less harmful ones to penetrate it.

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

When it comes to the UV-B, it can be absorbed by the ozone present in this layer, but not all the UV-B present will be absorbed by these molecules. 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 the ozone layer. Although considered the safest, UV-A can still pose harm if you are exposed to it in large amounts or for prolonged periods.

Where is the Ozone Layer Located?

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

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

The stratosphere is the only layer that is well-equipped to handle the unstable ozone molecules and for longer periods, as it is known as the stable or stratified layer and lacks vertical convection that allows the molecules to move up. However, the ozone layer is not synonymous to the stratosphere, since this layer is only confined in the lower region that is just above the troposphere.

While 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. There is also good ozone, and it is important to understand the difference between them.

Good ozone is the ozone found in the stratosphere, specifically in the ozone layer. As we already mentioned, this naturally-occurring ozone 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 the ozone layer. The more ozone present in this atmospheric layer, the better protected we are.

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

Ground level ozone or bad ozone has various health effects if you get exposed to it, such as:

  • May cause respiratory issues or exacerbate already existing conditions
  • Trigger eye irritation
  • Damage or kill plants
  • Make it difficult to breathe
  • Damage lung tissue and cause scarring
  • Increase susceptibility of plants to various stressors, such as diseases and pests
  • Agricultural yield reduction

Complicating matters is the fact that bad ozone is insoluble in water, which means our bodies are incapable of processing it. When ozone gas is ingested, it will simply pass through the lungs without being broken down. And because ozone is very reactive, it will immediately trigger various health issues and can even cause death.

The difference between them makes it clear why good ozone must be constantly replenished and bad ozone must be eliminated, or at least limited, with the latter being one of the main reasons for the creation of the Clean Air Act.

How is Good Stratospheric Ozone Formed?

While bad ozone can be considered man-made in some way because it involves man-made processes, the stratospheric ozone we consider as the good ozone is formed naturally.

21% of the molecules found in the entire atmosphere are oxygen, and this oxygen is crucial in the formation of 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. When a newly unattached oxygen atom collides with an oxygen molecule, it will immediately react and combine with it to form the ozone molecule. This ozone molecule has three oxygen atoms present, two from the existing oxygen molecule and 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 ozone are also fewer in number. On the other hand, the UV light necessary in this process decreases at it moves towards Earth. The stratosphere is the best location to form ozone because it meets the balance between the required UV light and oxygen molecules.

When Was the Ozone Hole Discovered?

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

In the past, ozone was believed to be just another gas found on earth. It was not until years later that scientists began to come up with the idea that this gas is vital to the planet and can 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, which we now know as the ozone layer.

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

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

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

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

The misconception about the newly discovered hole caused widespread alarm, as the public believed that it is a literal hole that will allow the UV rays to freely reach Earth and cause harm to people, especially to those who are directly underneath the ozone layer hole.

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

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

What Causes Ozone Depletion and the Hole in the Ozone Layer?

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

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

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

A specific type of cloud known as nacreous clouds, often called ‘mother of pearl’ clouds, is one of the main causes of the holes in the ozone layer. These clouds, including ice crystals, can only be formed in the ozone 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, while the ice crystals present in these clouds draw CFCs closer to it.

When CFCs reach the stratosphere and react with UV radiation, it breaks apart these CFCs and releases various gases, the most dangerous of which is the highly reactive chlorine. Once a chlorine atom interacts with an ozone molecule, it destroys it by getting the third oxygen atom from the ozone molecule and produces 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 with it and form a new oxygen molecule. Because the chlorine is now a free atom once more, it can again interact with another ozone molecule and destroy it. This destruction occurs faster than the time it takes to replenish lost ozone molecules, causing ozone depletion and increasing the size of the hole.

Unfortunately, it is not just chlorine that can destroy these ozone molecules. Bromine, which is also often released by CFCs together with chlorine, as well as other chemicals and compounds like hydrofluorocarbons, halons, methyl chloroform, hydrocarbons with bromine, and carbon tetrachloride, are also known to cause ozone depletion.

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

What is Happening to the Hole in the Ozone Layer?

Since its discovery, scientists have begun taking a closer look to understand what is happening to the hole in the ozone layer. After the events in 1985, they realized that the problem is more serious than they initially thought, and that this worldwide problem has been the result of human activities over the years.

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

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

The Montreal Protocol on Substances that Deplete the Ozone Layer that was created in September 1987 is a different story. It supplemented the Vienna Convention by aiming to phase out the ozone-depleting substances, or ODS, 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 and it was adapted 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 and they eventually came up with the goal of completely banning these substances by the year 2000. The urgency was felt by some countries, that they even started the ban years before the set deadline.

Even with the protocol in place, scientists are aware that it will take time before the ozone layer can recover. Because these substances are stable, which means they remain in the atmosphere even after decades, scientists do not expect the ozone layer hole to be gone until around 2040 to 2070.

After all, record lows of ozone 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. Because the number of CFCs present in the atmosphere have been in constant decline over the years after reaching record highs, the ozone layer hole has also begun to show signs of being repaired, which has now led to the smallest ozone layer hole since this hole was discovered. This is proof that the Montreal Protocol is effective.

While it was human activities that caused the ozone layer depletion, it is also human intervention that is now fixing it.

How Does Ozone Depletion Impact Human Health?

Ozone depletion became such a big deal for everyone because of its perceived impact on the human health, especially due to the misconceptions. Because the term ‘hole’ was used, the general public took it literally and believed that this hole will 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 the ozone layer has 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 the UV rays, particularly to UV-B, brought about by ozone depletion:

  • Skin cancer, including the non-melanoma kind
  • Development of melanoma considered malignant
  • Cataracts, which often lead to blindness
  • Snow blindness and other forms of photokeratitis
  • Damage to the cornea, retina, conjunctiva, and lens of the eyes
  • Compromised immune system
  • Polymorphic Light Eruption
  • Eye diseases
  • Premature skin aging and other forms of skin damage
  • Pterygium

You may have noticed that the health impacts brought about by ozone depletion are limited to the skin, eyes, and the immune system. It has also been discovered that while 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 that also serves as protection 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 in a particularly hot day without slathering on some sunscreen.

What Impact Does Ozone Depletion Have on Plant and Animal Life?

Think again if you believe that the impact of ozone 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 of them also have properties that protect them from radiation. Think of these plants having their own 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 an ozone depletion of 10% or higher. If this happens, certain plants may experience the following negative effects:

  • Cell changes that can result in irregularities with the pollination cycle, varying flowering times, and stunted plant growth
  • Greater susceptibility to plant diseases
  • Imbalance in terms of plant and herbivore competition
  • Decrease in yield
  • Issues with photosynthesis
  • Decline of nitrogen-fixing bacteria

Do note that because plants have different reactions to UV-B, exposure to it even in large amounts will have an unequal impact to these plants; some may be severely affected while others may have little reaction to it. UV-B can also be beneficial to some plants, but not if it gets overexposed to it, which is the case if the depletion of the ozone layer continues.


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

If the ozone layer 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, since only plants get to recover during the months when the ozone layer hole is smaller. This respite is crucial because if plants are not given time to recover from too much UV-B exposure, which is what will happen if the ozone layer 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 the ozone-depleting substances, the hole in the ozone layer is getting smaller, which 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 that we were all afraid of.

2 Minute Summary:

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

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

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

With the continuous depletion of the ozone layer, we are all prime candidates for the acquisition of various health issues, particularly involving our eyes, our immune system, and 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, we can also die from starvation, as 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 possibly do is to underestimate the impact of the depletion of the ozone layer.

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

Effects of Air Pollution on Human Health

What is your initial reaction when you come across a car that emits a lot of smoke fumes?

For many of us, it is to cover our mouths and noses with a handkerchief, or at least our hands. Because if we don’t, we are aware that the coughing fits we can get if we inhale that smoke is only a minor consequence.

You know that this emission coming from vehicles is just one of the contributors to air pollution, but what you may not be aware of are its other sources, with some of them being even more hazardous than vehicle emissions.

And because of these different air pollution sources, it can be expected that there will also be various effects of air pollution on human health.

It is important that you be informed with both the sources of air pollution and its effects, as well as other necessary information about it. Prevention is indeed better than cure, and the best way to prevent the health effects of air pollution is to understand what causes it in the first place.

What is Air Pollution?

Everyone knows that air pollution exists, but not all of them are aware of what it really is. Most people think that it only involves the dark smoke from vehicles and factories, especially smog, but they are unaware that it goes beyond that. Air pollution is one of those concepts that people think they are very much familiar with, only to discover that they still have much to learn about.

Ideally, the air in the atmosphere should contain mostly nitrogen, some oxygen, and a little bit of a mix of other trace gases to be considered completely clean and healthy for us to breathe in. But with air pollution, the essential nitrogen and oxygen are lessened, and harmful pollutants in the air increase at the same time. Because of this, the air quality is compromised.

Since these pollutants present also have toxic chemicals or compounds, air pollution is detrimental not just to humans but also to the environment, including plants and animals alike. And unlike what most people think, it is present both indoors and outdoors and in both urban and rural areas.

And because air easily circulates, air pollution can also easily transfer to and affect other areas.

Air Pollution Facts

There is a lot of misconception about air pollution, that is why it is important to know the most important facts about it, including the reasons why this environmental issue should be taken seriously by everyone.

  • Air pollution is due to multiple sources and not just the smoke coming from cars. The most dangerous ones are those that are invisible to the naked eye.
  • This type of pollution is considered more dangerous than other forms because of the pollutants involved. Being mostly invisible means that we are constantly exposed to them without our notice. Also, the pollutants themselves generally contain toxic substances.
  • The amount of air pollutants produced annually is believed to be greater than the total amount of water, ground, and land pollutants.
  • These air pollutants can cover large distances, with scientists finding out that air pollution coming from Asia has been affecting the western region of the US for the past two decades.
  • In a recent report, China and India were discovered to be collectively responsible for more than half of the deaths worldwide due to air pollution.
  • Exposure to air pollution can have various effects on anyone, from a simple cough or eye irritation to lung cancer.
  • It happens both indoors and outdoors.
  • Urban areas generally have the worst air quality due to the amount of traffic present.
  • The US only ranks 10th worldwide in terms of having the best air quality. And among its states, California has consistently topped the list of states with the worst air pollution in the entire US.
  • Air pollution indirectly affects the global economy, with the loss amounting to billions of dollars on average. Productivity is lessened because of illnesses and death related to this problem, which results in loss of income for companies.
  • Certain pollutants not only worsen air pollution but also exacerbate other global problems, like climate change
  • Air pollution has long been considered as responsible for claiming so many lives each year, but it is now considered as the 4th leading cause of death worldwide
  • While occurring both indoors and outdoors, indoor air pollution is generally considered as more dangerous, as it is more concentrated
  • More people die from a stroke caused by air pollution, followed by heart disease and cancer and lung diseases

To sum it up, air pollution has become a worldwide problem affecting not just us humans, and it is not caused by a single factor. And unless we continue to find ways to address this problem, it is bound to get worse.

What Causes Air Pollution?

You may be aware that there are different causes of air pollution, but you will be surprised to know that the most common ones you can think of are not the only ones. There are also other sources of air pollution that you are probably not aware of, especially those that are invisible to the naked eye.

Air pollution happens due to the excessive amounts of air pollutants present, which are composed of mainly gases, liquid aerosols, and solid particles, that the environment is unable to absorb or break down. These pollutants are those that are not always present in the atmosphere and are also mostly invisible.

The sources of pollutants, in general, can either be man-made, also called anthropogenic, or naturally-occurring. But with air pollution, the main cause is attributed to anthropogenic causes.


Any activity that involves the use or burning of fossil fuels is seen as the biggest culprit of air pollution. Because industrial processes use up the largest amount of fossil fuels, they are considered as the major cause of air pollution. At the forefront of these is facilities and equipment that generate power, such as power plants, especially those that use coal.

Other industrial causes include:

  • Emission coming from production and manufacturing facilities, like factories and other industrial plants
  • Mining activities, like drilling, blasting, and extracting
  • Facilities that produce chemical products and metals
  • Diesel generators
  • Plastic manufacturers and facilities that process them
  • Gas and oil refineries
  • Smelting
  • Industrial heating devices that require fossil fuel
  • Waste incineration and use of landfills


Not a lot of people know that certain household activities also contribute to air pollution, particularly those that also involve the use of fossil fuels, as well as the use of household products that emit pollutants.

Did you know that you also release pollutants while you cook, with the amount depending on your heating source? Whether you use electricity, gas, or wood, these sources will contribute to air pollution in your home because they can produce formaldehyde, carbon monoxide, and other pollutants. The cooking ingredients themselves may also release pollutants as they are heated.

When you use the following household products, certain air pollutants are also released:

  • Solvents
  • Cleaning products, especially disinfectants
  • Air fresheners
  • Laundry products
  • Paint
  • Glue and other chemical adhesives
  • Personal care products, such as deodorant sprays and hairsprays
  • Tobacco products, such as cigarettes
  • Pest or insect sprays

Home construction or renovation is also known to contribute to air pollution because of the materials involved. Old homes are even more dangerous to work with, as they may possibly release lead (can’t recall if there is an article about lead in the check4lead website, but it can be linked here) and asbestos, which are also known air pollutants, during construction work.


Another major cause of air pollution is the transport sector, especially those that emit carbon dioxide. As you know, cars are also one of the major sources of these pollutants because of their exhaust fumes, with diesel-powered cars known to be the biggest culprit of vehicle emissions. While the bigger trains and planes also use fossil fuel, it is the smaller cars that pollute the air the most because these cars greatly outnumber other modes of transport, which means they collectively use up more fossil fuel.


The agriculture industry is also known to contribute to air pollution, and it has been discovered to be the biggest contributor to particulate pollution. Most of the pollutants come from the use of various agricultural products like fertilizers and pesticides, especially those that contain ammonia. Not only that, various farm equipment also use fossil fuels in their operations. Crop dusting and burning is also another farming activity known to release air pollutants.

Natural Causes

While natural causes of air pollution have less of an impact, they still add to the overall air pollution. Some of them may be preventable, while others occur instantaneously and give us no chance to prevent them.

Among the natural causes are:

  • Volcanic eruptions
  • Radioactive decay
  • Decomposition of plants and other organic matter
  • Forest fires
  • Whirlwinds
  • Dust and sand storms
  • Mold
  • Pollen and other natural allergens
  • Animal droppings
  • Wind erosion
  • Sea-salt spray
  • Animal digestion that produces methane, particularly involving cattle
  • Plants that produce volatile organic compounds
  • Hot springs
  • Fog and mist
  • Soot
  • Certain gases, such as ozone and radon
  • Release of gas due to natural processes

While man-made causes are known to produce more air pollutants than natural ones, both of them contribute to the overall air pollution every day.

What is the Biggest Source of Air Pollution?

You may have noticed that we mentioned fossil fuels plenty of times in the previous section, so it should come as no surprise that the biggest source of air pollution, in general, is any activity that involves its combustion.

People are not aware that plenty of our daily activities involve the use of these fossil fuels, directly or indirectly, and this has detrimental consequences to the environment, especially when left unchecked.

In particular, the biggest source of air pollution is our use of automobiles. Transportation not only uses up a lot of fossil fuels, but it also disturbs pollutants on the ground that can easily become airborne, such as road dust. Also, cars are responsible for both primary and secondary sources of air pollution.

Cars are considered as a primary source of toxic gases and air pollutants. While other means of transport also produce these pollutants, cars vastly outnumber their volume, which is why they collectively produce the most pollutants. Some of these pollutants will react with other pollutants, or even themselves, resulting in the formation of secondary pollutants like ozone, acid rain, and smog.

Primary air pollutants that are emitted by cars, as well as other modes of transport, are:

Because most of the air pollutants coming from cars are due to the burning of fossil fuels, different car manufacturers have been trying to cut back on its use. This is why they are now developing cars that are more eco-friendly, such as hybrid and electric cars, in hopes of lessening their contribution to air pollution.

Different Types of Air Pollution

Most people have no clue that there are different types of air pollution, namely indoors and outdoors. They believe that air pollution only happens outdoors where all the smog is present, and staying inside a confined space, like their home, protects them from all air pollutants.

Why air pollution is not limited outdoors has to do with the different types of air pollutants present. And if you recall, these pollutants can either be primary or secondary, which means they may be pollutants themselves, and at the same time be responsible for the creation of other air pollutants. With this ability, it is no wonder these pollutants are abundant.

The EPA has identified the following as the “criteria pollutants” or those that are most common in the United States:

  • Ground-level ozone
  • Lead
  • Particulate matter
  • Nitrogen Dioxide
  • Sulfur Dioxide
  • Carbon monoxide

Aside from these six common pollutants, the agency has also identified 187 hazardous air pollutants that are being monitored through the Clean Air Act. All these pollutants can easily be transferred from one place to another, and their minuscule sizes means they can easily pass through the smallest of gaps.

You already know that activities that involve burning fossil fuels are the major source of air pollution, with the use of cars being at the forefront. In fact, it is generally responsible for most of the air pollutants. Most of these activities are done outdoors, that is why we get the highest amounts of exposure to air pollutants when outside. And if you recall, most of the causes of air pollution are also found outdoors.

Aside from most of the natural and man-made causes we mentioned earlier, outdoor air pollution also includes the following:

  • Cigarette smoke
  • Particulate matter produced from activities involving burning
  • Toxic gases, especially those produced by industrial processes and facilities
  • Ground-level ozone
  • Smog

What makes outdoor air pollution the most familiar to most people is the fact that it is associated with smog. This is the most visible sign of air pollution and is formed by reactions between various pollutants. Because smog appears in the form of a dark haze or cloud, people immediately associate it with air pollution. This visibility of smog makes people aware of outdoor air pollution.

On the other hand, smog does not form inside any house or building, letting people think that there is no such thing as indoor air pollution. After all, the sources of indoor air pollution seem to be less than that of outdoor air pollution, and any visible smoke inside the house, such as due to cooking, is not seen as air pollution but simply a nuisance that will disappear in a few.

Sources of indoor air pollution, which are mostly due to indoor activities, include:

  • Building materials
  • Household and personal care products and chemicals
  • Gases
  • Various allergens found indoors and outdoors, such as mold, pollen, pest droppings, and fungal spores
  • Tobacco smoke
  • Cooking

However, this does not mean that you should not take indoor air pollution seriously. While indoor air pollution is smaller in volume, it is more concentrated than outdoor air pollution, which makes it more dangerous. This happens because air ventilation is poorer indoors than outdoors, preventing the pollutants from moving around freely, which leads to them to have a higher buildup indoors. And because we spend most of our time indoors, we get exposed to indoor air pollution more.

Clearly, these two types of air pollution pose different dangers, with higher amounts for outdoor air pollution and higher concentrations for indoor air pollution. Exposure to any of these two types is dangerous, and it is even more amplified by the fact that most of them are invisible to the naked eye, which makes avoiding these pollutants a challenge.

PM2.5 Pollution

People tend to associate smog with air pollution the most, not knowing that there is a much more hazardous enemy in the form of PM2.5 pollution. Particulate matter comes in two general categories, PM10 and PM2.5, but the latter is considered more dangerous. In fact, scientists agree that it is the most lethal among air pollutants

Also called fine particles, PM2.5 is named as such because of its size, measuring only 2.5 microns or less. To put it into perspective, the average strand of human hair has a diameter of 50 to 70 microns, which means you need an electron microscope to see PM2.5. Because of its size and weight, it remains airborne longer and anyone can get exposed to it much easier and at higher amounts.

PM2.5 is produced through combustion of any kind. Since the burning of fossil fuels is known to be the biggest contributor to air pollution, it means PM2.5 is also abundant in the atmosphere. And since they can also react to other air pollutants, they can produce even more dangerous compounds.

All these characteristics make every one at risk of PM2.5 pollution. What makes it even worse is that when inhaled, the particles are so small that they immediately penetrate the lungs and settle there, leading to all sorts of illnesses. Not only that, but they can also affect soil and water quality, which can compromise our food supply.

Because of all these, various government agencies are now keeping a closer eye on PM2.5 more than any other air pollutants. The Air Quality Index (AQI) now also measures the amount of PM2.5 present, together with PM10.

What are the Effects of Air Pollution on Human Health?

Everyone knows that air pollution has various effects on the human health, but many of them are not aware that these are more just coughing fits. Anyone can get exposed to these harmful air pollutants, but there is no one more vulnerable to it than the children and the elderly.

Children spend the most time outdoors where air pollutants are abundant. And because they are still small, their bodies are not yet fully equipped to handle these pollutants, as they are still in the development stage. They also get exposed to ground-level pollutants more than adults, especially those that are emitted by cars.

The elderly are also among the most vulnerable to the effects of air pollution, but only next to children. While their bodies can defend themselves better against these pollutants, age plays a factor; the older the adults are, the less capable they are to handle air pollution and other environmental hazards. And if they already have pre-existing conditions, air pollution can increase the symptoms they experience or aggravate their conditions.

Some of the health effects anyone can possibly experience or acquire due to exposure to air pollution include:

  • Eye, nose, and throat irritation
  • Lethargy, weakness, or constant fatigue
  • Issues with the reproductive organs
  • Damage to the cardiovascular system, including the hardening of arteries, increased risk of stroke and heart attacks, left ventricular hypertrophy (LFV), hypertension
  • Diabetes
  • Allergic reactions
  • Various respiratory diseases, including asthma, pneumonia, emphysema, chronic bronchitis, chronic obstructive pulmonary disease (COPD)
  • Mobility issues
  • Mental health issues, such as anxiety, dementia, schizophrenia, behavioral changes, lower IQ levels, and depression
  • Headaches
  • Liver and spleen damage
  • Blood-related issues, like anemia
  • Premature birth, miscarriage, low birth weight, compromised fetal growth, and the child possibly having autism (when exposure happens while pregnant)
  • Nausea
  • Compromised development of the nervous and respiratory systems in children
  • Different types of cancer
  • Tightness of chest or chest pains
  • Skin issues
  • Weaker immune system
  • Irregular heartbeat
  • Wheezing and coughing
  • Lung issues, like decreased lung function, damage and scarring, loss of lung capacity
  • Osteoporosis

You may have noticed that many of these health issues are not related to the respiratory system, which is contrary to what most people would expect. This just proves how dangerous air pollution is, with death being its worst consequence.

How Does Air Pollution Affect the Environment?

Air pollution not only affects humans but also the environment, and how it does so mainly has to do with the pollutants present. These air pollutants can either cause different harmful environmental conditions or worsen existing ones, just like how air pollution affects health.

Air pollution is seen as the cause of the following environmental hazards and effects:

  • Acid rain – is due to sulfur dioxide and nitrogen oxides that cause a reaction with various chemicals and compounds in the atmosphere. Acid rain can fall not only as rain but also snow and fog and can damage vegetation, as well as affect water quality by making it acidic and harmful to aquatic life and those who drink from it
  • Damage to crops and forest – air pollution can directly cause damage to vegetation, not just acid rain. Ground-level ozone, in particular, can affect the growth and yield of plants and even reduce their lifespans because it can make them more susceptible to pests and diseases
  • Harm to wildlife – just like humans, wildlife can also acquire all sorts of health problems due to air pollution, such as reproductive issues, birth defects, and various diseases
  • Eutrophication – nitrogen and phosphorus from various air pollutants will promote harmful algal bloom that can kill off marine life
  • Haze – just like smog, haze is a form of fog but is made up of air pollutants that remain suspended in the air and block sunlight, affecting visibility

Aside from causing the above conditions, air pollution is also known to contribute to global warming and ozone layer depletion (add link to ozone layer depletion article). The greenhouse gases considered as air pollutants are attributed to global warming, and certain air pollutants are also considered as ozone-depleting substances.

When air pollution affects the environment, humans are also affected. The plants and animals we consider as our food supply may be lessened or compromised because of air pollution. And if we consume animals that have ate and drank contaminated plants and water, this contamination may also affect us.

What are the Global Effects of Air Pollution?

Because the pollutants can easily travel once airborne, the effects of air pollution can be felt globally. The air pollutants in one country may be blown away to another country, which means air pollution in one country can worsen due to the air pollutants coming from another country.

Unfortunately, those in developing countries are the most affected because they use more fossil fuels than developed countries, particularly when cooking and heating their homes. These countries also have many of the world’s industrial facilities and engage in agricultural activities the most, which exacerbates their problem.

Most of those on the top 50 list of cities with the world’s worst air pollution, particularly in terms of PM2.5, belong to only these countries: India, Pakistan, Bangladesh, and China. These countries are also known as the hub of the world’s industrial facilities, that is why they are expectedly on the top of the list of countries with the highest annual concentrations of PM2.5. Bangladesh, Pakistan, and India are the top three countries, while China is now in 12th place, which is a vast improvement.

The top 10 countries with the highest PM2.5 concentrations are:

  1. Bangladesh
  2. Pakistan
  3. India
  4. Afghanistan
  5. Bahrain
  6. Mongolia
  7. Kuwait
  8. Nepal
  9. United Arab Emirates
  10. Nigeria

While these countries are known to have poor air quality due to the PM2.5 concentrations present, the majority of all the countries worldwide exceed the global standards set. This is the reason why the whole world seems to experience its effects.

By now, you are aware of the numerous health effects of air pollution on humans and why it is becoming one of the leading causes of death worldwide. The WHO even reports that more than 7 million people die annually due to both indoor and outdoor air pollution, with most of these deaths occurring in developing countries in Asia and Africa. This number does not include those who acquired air pollution-related symptoms and illnesses and survived, which is expected to be higher.

Climate change has become a global issue in recent times, with its effects felt all over the world. Unbeknownst to many, air pollution and climate change are closely linked to each other, as the pollutants common in air pollution can cause various reactions in the atmosphere that directly affect temperatures. Climate change is associated with greenhouse gases, which is also a known air pollutant. By lessening air pollution, climate change is also reduced.

This scenario also applies to the depletion of the ozone layer. The hole in the ozone layer gets bigger with the increase of ozone-depleting substances that get released in the atmosphere. Many of these compounds that cause the depletion are also known air pollutants, such as volatile organic compounds and hydrochlorofluorocarbons. If these pollutants are lessened, ozone layer depletion is also lessened.

The environmental effects of air pollution mentioned earlier is also felt in various parts of the world, especially acid rain that resulted in the deaths of vegetation and marine life. Because the pollutants needed to produce it can travel long distances by wind, acid rain can happen anywhere. One example is the fact that Norway experiences acid rain that is due to pollutants coming from the United Kingdom.

The widespread reach of air pollution, including its effects, has been a cause of global concern for years now. While there have been signs of improvement in terms of air quality in some countries, the consensus is that there is still much to be done. To solve this, different countries have made their own legislations and they also adapted universal policies to follow, such as through the UN Sustainable Development Goals and the Geneva Convention on Long-range Transboundary Air Pollution.

Lessening the global effects of air pollution is still a work in progress, but we are slowly starting to see improvements that affect everyone.

Air Pollution Statistics

To better understand the seriousness of the problem, here are other important statistics involving air pollution you need to know:

  • More than 90% of the people worldwide, or 9 out of 10, are now living in places with poor air quality that exceed the standards of the World Health Organization
  • As many as two billion children are believed to be severely exposed to outdoor air pollution. And in 2016, 600,000 children reportedly died due to acute lower respiratory infections attributed to air pollution.
  • 1 out of 10 children under the age of 5 years old died because of illnesses due to air pollution
  • In the US, as many as 11 million people are residing in counties where the air quality also fails to meet the national standards
  • In 1952, the air pollution in London was so bad that almost all modes of transportation had to be stopped and people were unable to see their own feet while walking. This incident, which lasted five days, became known as the Great Smog of London of 1952 and was responsible for thousands of deaths that are said to range from a total of 4,000 to 10,000.
  • Around 800 people per hour or 13 people per minute die due to causes related to air pollution. This means 1 out of 8 or a total of 7 million lives are now lost annually, with almost all of these deaths happening in developing countries
  • Out of the 7 million average premature deaths, 4 million is due to outdoor air pollution and 3 million is due to indoor air pollution
  • People breathe in an average of 20,000 liters a day. Just imagine the number of pollutants you inhale, depending on where you live
  • Crop production has also been affected by air pollution that as much as 50 million tons worth of yield is lost annually

All these figures are enough to alarm not just scientists but also world leaders to move quickly and come up with ways to address the problem. With numerous legislations and calls to action over the years, we are now reaping its benefits. The best proof of this is the improving overall condition of air quality throughout the world.

The world has come a long way if we were to compare the figures now to those in the past before any kind of intervention occurred. However, the battle is not yet won because air pollution still exists and millions of people are still dying because of it every year.

How to Reduce Air Pollution

Surprisingly, it does not require fancy machinery nor a lot of resources to reduce air pollution. For most people, they are not even aware that the simplest measures really do go a long way when it comes to dealing with this problem.

And if you are wondering how you can be part of the solution, here are some of the best ways for you to do so:

  • Cut back on your use of anything that requires power and switch off electrical appliances and equipment, as well as lights, that are not in use. Conserving energy means fewer fossil fuels are needed to produce the needed energy.
  • Use appliances with an Energy Star label, as they are confirmed to use power more efficiently. Also, consider installing alternative energy sources, such as solar panels
  • Go places using mass transport, biking, or simply walking.
  • Make sure that your car, boat, and any other engine-powered machinery are regularly maintained to prevent fuel spills, ensure fuel efficiency, and prevent tailpipe smoke from coming out. Overweight cars and tires in poor condition will also cause an increase in fuel combustion
  • Refuel during the evening because the temperature is cooler and will lessen the number of pollutants that can be produced. This principle also applies to the use of any gas-powered equipment, such as those for gardening
  • If possible, switch to eco-friendly or hybrid cars and equipment, especially those that are manually-powered
  • Choose paints, cleaners, and other personal and household product that are labeled environment-safe, especially those that have little to no VOC present
  • Avoid idling your car for long periods
  • Ideally, use household appliances and equipment, such as washing machines and dishwashers, only with a full load to conserve electricity
  • Instead of doing backyard burning for biodegradable material, create a compost pit or mulch them
  • Lessen your use of wood, whether in cooking, heating, or any other activities that require it to be burned
  • Ensure that your household products are properly sealed, especially those that contain VOCs, to prevent these compounds from evaporating
  • When driving, stay within speed limits to lessen fuel combustion. The faster your car runs, the more fuel is needed and the more pollutants are released
  • Have a garden and grow plants that are known to purify the air
  • Stop smoking, whether indoors or outdoors
  • Participate in local initiatives aiming to curb air pollution

You may be familiar with many of these tips to reduce air pollution, but you may not be aware of the impact these small changes can bring to the entire world. If we all do our share, there is a 100% guarantee of good results that everyone will benefit from.

But since having zero air pollution is not going to happen anytime soon, you should also ensure that you minimize your exposure to it at the same time, especially on days when the AQI levels are forecasted to be high.

Here are some of the ways you can keep yourself protected against air pollution to avoid experiencing its health effects:

  • Keep yourself updated with the AQI to learn when the pollution levels are forecasted to be elevated
  • Avoid staying outdoors and doing intensive physical activities during the times when pollution levels are high, as well as near roads, highways, and any other location with a lot of traffic
  • If exposure is inevitable, wear face masks(link to check4lead?), particularly those with an N95 or P100 rating
  • Cover your mouth and nose when dealing with smoke, even those coming from cigarettes, if a suitable mask is unavailable.
  • Install air purifiers in your home, especially those that are capable of filtering even the smallest PM2.5 particulates. You can also place purifying plants to help improve indoor air quality.
  • Ensure proper ventilation by installing air vents and exhaust systems in your home, especially in the kitchen and bathrooms, and adding filters that can block air pollution.
  • Air out your home every now and then to prevent pollutants from settling and to lessen the concentration present. it is advisable to do it between 3 to 5 pm when the PM2.5 levels are generally lowest
  • Remove any mold and mildew present

Doing these measures will not just protect you from air pollution, but it will also help lessen the levels present. That way, the time when we will all constantly breathe in clean air without any pollutants present may happen sooner than later.

What is the Montreal Protocol? Its Importance


The discovery of the ozone layer hole meant bad news for everyone. Because they found out that the main cause of this phenomenon is various man-made activities, scientists and world leaders alike knew that man-made activities will solve the problem. Thus, the Montreal Protocol was born.

Since they identified various ozone-depleting substances as the catalyst for this problem, it became the main focus of the Montreal Protocol. They believed that addressing the root cause is the best way to fix the problem, that is why they decided on the implementation of a stepwise manner of phasing out these ODSs. The initial purpose was to simply limit their use, but studies showed that this is not enough and the ideal way of dealing with the problem is to completely prohibit these substances.

Fortunately, they were right in their assumption. The gradual phasing out of ODSs yielded positive results, namely the levels of the ODSs are in constant decline since it was enacted and now, the ozone layer hole is smaller than ever. It also indirectly made positive changes to other world problems, namely poverty, climate change, global food supply, and public health.

All these positive impacts make the Montreal Protocol an important global treaty.

It was the talk of the town, rather, the world, when it was discovered that there is a hole in the ozone layer decades ago. Common folk took it literally, believing that there is an actual hole in that layer and anyone who ends up under it will get the worst case of sunburn, among others. Scientists would later clarify that this hole is not an actual hole but a phenomenon that results in ozone layer depletion(link to article on ozone layer depletion?).

One of the immediate global reactions to this discovery is to craft various laws to address the issue. These were enacted with the goal of stopping further damage to the ozone layer. But among these different laws so far, there is nothing that is more all-encompassing than the Montreal Protocol.

Before the establishment of the protocol, most of the local laws focused on lessening the use of ozone-depleting substances to lessen its effects on the ozone layer. It was the Montreal Protocol that took a more active role, as its primary goal is to completely prohibit the use and production of such substances after some time.

Most people are unaware of what the Montreal Protocol is and its importance. While you do not need to read the entire protocol word for word, it is important to understand its essentials to know how it has evolved over the years and why this landmark protocol is acknowledged as the most successful environmental law and is seen as the major catalyst for the recovery of the ozone layer.

What is the Montreal Protocol and Why is it Important?

Most people may have likely heard the Montreal Protocol in passing but have no clue what it really is and why it is important. They may have a vague idea that it is related to the ozone layer because of the abundance of news about it in the past, but they do not fully understand why this is considered a globally significant law.

The ozone layer was initially believed by scientists to remain permanently undamaged, but it was discovered over the years that this is not the case. In fact, scientists made a startling discovery in 1985 that there are parts of the ozone layer above Antarctica where the levels of ozone have dropped below the historically low levels. This discovery was instrumental in crafting the Vienna Convention for the Protection of the Ozone Layer in 1985.

Despite being considered as one of the landmark environmental laws, the Vienna Convention mostly focused on research and fact-finding, as there were still some skeptics about the reports on the ozone layer hole, and even the ozone layer itself. Because of this, the participating countries had a hard time agreeing on what the control measures should be and dealt more on research cooperation, and they were unable to craft laws that will deal with the goal of reducing the ozone layer hole.

To fill this important gap, the Montreal Protocol on Substances that Deplete the Ozone Layer, or simply the Montreal Protocol, was enacted in September 1987. This protocol was also the result of the scientific community and world leaders finally reaching a consensus on matters involving the ozone layer after much confirmatory research and studies.

Unlike the Vienna Convention, the Montreal Protocol took a more active role in addressing the matter. Because it was confirmed that certain substances negatively affect the ozone layer once they reach the stratosphere, the primary goal of the Montreal Protocol is to gradually phase out these substances, which will reduce the depletion of the ozone layer.

Montreal Protocol Summary

International laws and protocols are known to be extensive, that is why we have provided a summary of the multilateral Montreal Protocol to help you understand this environmental treaty better and why its success is beneficial for all humanity.

Due to the discovery that the ozone layer is becoming depleted and is mainly due to certain substances being released to the atmosphere that reach the ozone layer, world leaders decided to be more active in dealing with the issue.

The concrete actions to address the problem started with the establishment of the Vienna Convention, whose goal was to protect humans and the environment from the effects of ozone layer depletion. But because this convention did not establish rules to achieve this, it resulted in the adopting of the Montreal Protocol in 1987.

This particular protocol aimed to decrease the substances that cause the depletion of the ozone layer by initially phasing down their production, importation, and use, starting with chlorofluorocarbons (CFCs) and halons. These two were widely-used in various household products considered essential, that is why it was decided that they must be phased down first.

Because the immediate outright banning of these substances will also pose a problem, the Montreal Protocol promoted the gradual phasing down of these substances according to a set timetable. This will allow people ample time to discover more eco-friendly alternatives and make adjustments to various products that rely on these substances to work.

The protocol divides countries into two specific categories, namely developing and developed countries, and this categorization results in different timetables. Developing countries are generally given more time for the phasing out of these substances than developed countries, particularly with a 10 to 15-year window between them. They acknowledge the challenges that these developing countries will face, particularly financially and technologically, to comply with the protocol, hence the longer timetable.

While phasing out these harmful substances is the main goal of the Montreal Protocol, it also acknowledges the fact that there are still some instances when using them is necessary. Because of this, they came up with provisions specifying when they can be used but only in controlled amounts and if they meet the strict criteria set. To be precise, if the purpose of using these substances is considered essential or critical, it may be allowed if it meets the specific conditions set.

The main goals of the Montreal Protocol during its creation were:

  • Start the phasing down of CFCs in 1993, decrease it by 20% in 1994 (when compared to the consumption level in 1986), and finally reduce it by half by 1998
  • Freeze or restrict the manufacture and use of three specific halons in developed countries by 1993, comparing their levels to the 1986 levels
  • Restrict the trading of these substances between signatories and non-participants to prevent the transfer of facilities involved in their production to non-signatory countries

From phasing down and limiting its use, the Montreal Protocol eventually changed its main objective to the phasing out of these substances in the future. CFCs are the first to be phased out, followed by the other substances that were later added to the list after various amendments to the protocol over the years.

In order for those developing countries to meet the Protocol’s goals, the signatories eventually established a Multilateral Fund. The purpose of this fund is to aid these particular countries meet the timelines set in the gradual phasing out of these harmful substances. And to check on the progress of all the signatories in meeting the established timeframes, the Protocol requires the submission of progress reports and assessments from every member party.

Fortunately, all these efforts paid off and continue to do so, as the ozone layer hole is now at its smallest size since it was first discovered. Not only that, the amount of ozone-depleting substances present has decreased by 98% compared to the levels back in the 1990s.

The Montreal Protocol has achieved so much in a relatively short period of time compared to other environmental laws.

Which Problem Does the Montreal Protocol Address?

You may have guessed by now that the Montreal Protocol addresses the problem of the depletion of the ozone layer. While the purpose of the Vienna Convention is also to protect the ozone layer, it failed to establish global concrete actions to do so. The Montreal Protocol, under the umbrella of this Convention, was the first of its kind to take a more active approach with the phasing down of ozone-depleting substances, which later lead to an outright banning but done in steps.

Had it not been for this landmark treaty, scientists believed that the ozone layer may be gone by the year 2050, and lead to catastrophic consequences for everyone. Scientific evidence has shown that the ozone layer hole has been growing at an alarming rate since its discovery, and the Montreal Protocol managed to slow it down over the years.

UN Secretary-General Antonio Guterres also mentioned that the Montreal Protocol will also address other key global problems. In particular, this protocol is also believed to help meet the Sustainable Development Goals (SDG) set in terms of global poverty, health, climate change, and food supply. By addressing ozone layer depletion, they know that it will set a positive chain reaction and also address the other problems indirectly caused or worsened by the ozone layer hole.

How Does the Montreal Protocol Reduce Ozone Depletion?

The Montreal Protocol acknowledges the fact that it is man-made activities that are the biggest catalyst of ozone layer depletion and that it is vital to reduce this. In particular, there are certain substances that have the biggest effect on the ozone layer.

While the ozone layer hole is also caused by a natural phenomenon that occurs during spring, scientists found out that these ozone-depleting substances (ODS) cause the rapid increase of the hole. Because of this discovery, they realized that by reducing the source of the depletion, it will lead to the reduction of the depletion itself.

However, they acknowledged that this was easier said than done because these substances were abundantly used for so long, not knowing that they remain in the atmosphere for a long time. When the ODS reaches the ozone layer, they destroy the essential ozone molecules. With less ozone present, the size of the ozone layer hole increases.

Scientists have also made an unfortunate discovery that ozone-depleting substances stay in the atmosphere longer than desired. While most of them can linger for years, there are specific ODS that remain in the atmosphere even for decades. CFCs were discovered in the 1920s, but it was only around the 1980s when it was confirmed to be harmful to the ozone layer. This means for more than six decades, ozone was destroyed faster than it was created because of the ODS present.

CFCs and other ozone-depleting substances were widely used in various consumer goods for decades, such as air conditioners, refrigerators, and aerosol cans. Manufacturers even reportedly produced as much as 1.2 million tons of ozone-depleting substances in 1986 to meet consumer needs. This demand meant that there were no limits in the production of ODS and the products that use them at that time.

But with the introduction of the Montreal protocol, it led to the much-needed control over these substances. By limiting the ODS, its production lessened and manufacturers had to come up with alternatives for products that require ODSs to function. With this move, it led to the much-needed increase in the creation of ozone molecules to reverse ozone layer depletion.

Scientists have acknowledged the critical role the Montreal Protocol played in achieving this feat, which further proves its effectiveness. Despite the ozone layer being capable of “healing itself” it cannot do so if the ozone-depleting substances had not been limited or completely banned.

What Substances Deplete the Ozone Layer?

Based on scientific research and evidence, there are more than a hundred substances that deplete the ozone layer, and these are collectively known as ozone-depleting substances. These ODSs are man-made compounds or chemicals that typically contain chlorine and/or bromine and combines with fluorine, hydrogen, and carbon.

The ODS that combine any of the atoms above are known for their stability, allowing them to reach the ozone layer undamaged. And unlike other compounds, the rain cannot dissolve or push them back to earth, which means they are free to drift upwards anytime.

When these gases reach the ozone layer, the ultraviolet radiation coming from the sun will break the compounds apart and separate the chlorine and bromine, turning them into free atoms. Once they interact with ozone molecules, a reaction will occur that leads to the destruction of the ozone molecules.

A chlorine or bromine atom can singlehandedly destroy at least 100,000 ozone molecules before vanishing. And since these are abundantly present in ODS, they cause massive loss of ozone molecules that leads to the depletion of the ozone layer itself.

Simply put, any substance that contains either chlorine or bromine, or both, can become a catalyst that will cause the depletion of the ozone layer.

Which Chemicals are Controlled by the Montreal Protocol?

Because of the identification of the various ODSs over the years, the Montreal Protocol established control over the production and use of such chemicals. To make it easily identifiable, they sorted these chemicals into the following general categories:

  • Chlorofluorocarbons
  • Halons
  • Hydrochlorofluorocarbons
  • Carbon Tetrachloride
  • Methyl Chloroform
  • Methyl Bromide
  • Bromochloromethane
  • Hydrobromofluorocarbons

The full list of chemicals controlled by the Montreal Protocol can be found here.

Chlorofluorocarbons, or CFCs, were the first chemicals to be identified as ozone-depleting. CFCs proliferated in the atmosphere for decades because of their stability, fire resistance, non-toxicity, and effective heat absorption. They were used as coolants for refrigerators and air conditioners (with Freon being its most identifiable form), solvents, aerosol propellants, and blowing agents for foams. CFCs are a combination of chlorine, carbon, and fluorine atoms and are also considered as greenhouse gases.

Best known as an integral component of fire extinguishers, halons were also identified as an ODS early together with CFCs. Halons are made up of fluorine, bromine, and carbon and are safe for use, as long as it is within recommended levels or concentrations. Despite this, its ozone-depleting potential or ODP is the highest because of the bromine present. Halon 1301, in particular, has the highest ODP among all known ODSs.

Developed as alternatives to CFCs, hydrochlorofluorocarbons or HCFCs consist of chlorine, carbon, fluorine, and hydrogen atoms. Hydrogen makes the HCFCs more stable than CFCs and is broken down in the stratosphere, causing less damage to the ozone layer. Despite this, HCFCs are also considered greenhouse gases and this prompted it to be eventually banned.

Carbon tetrachloride was once essential to the production of CFCs because it was used as feedstock or raw material before the Montreal Protocol was enacted. Consisting of carbon and chlorine, it was also used in agricultural pesticides and fumigants, industrial solvents and paints, fire extinguishers, pharmaceuticals, and dry cleaning agents.

Methyl chloroform was also developed as a substitute, but this time for carbon tetrachloride. Known to be hazardous to humans, methyl chloroform or 1,1,1-trichloroethane consists of chlorine, hydrogen, and carbon. It was often used as an industrial solvent, particularly for degreasers, adhesives, and cleaners, especially of metals and electronics, that is why it was widely used in the manufacture of equipment and electronics.

Primarily used in the agriculture industry because of its effectiveness as a pesticide, methyl bromide or bromomethane is another chemical considered as an ODS. It is also used as a fumigant for agricultural products and soil fumigation, disinfectant for food-processing facilities, as well as in the quarantine and pre-shipment of trade goods. Composed of hydrogen, carbon, and bromine, the Protocol still allows its controlled use, as there are no effective alternatives for it yet.

Bromochloromethane is also known as Halon 1011 but is not considered halon, since it is a combination of chlorine, carbon, hydrogen, and bromine. It was also formulated as an alternative to carbon tetrachloride for use in fire extinguishers but is known as a toxic substance.

Also known as HBFCs, hydrobromofluorocarbons exhibit the same properties as CFCs, HCFCs, and halons due to its chemical composition. HBFCs consist of a frame of hydrogen and carbon, with a bromine or fluorine attached to it. But unlike its counterparts, it was not extensively used worldwide.

Among these, chlorofluorocarbons, methyl chloroform, carbon tetrachloride, and hydrochlorofluorocarbons emit chlorine, while methyl bromide and halons release bromine. So far, CFCs, halons, HBFCs, carbon tetrachloride, methyl chloroform, and bromochloromethane are already phased out, while HCFCs and methyl bromide will follow suit after several decades.

Montreal Protocol Countries

While it now seems that the majority of the world complies with various measures to prohibit the production and use of ODSs, not all of them are part of the original countries that enacted the Montreal Protocol. In fact, only 46 countries belonging to the United Nations back then were the first signatories. Despite this, they achieved major stride, which prompted the other nations to become signatories later on.

The 46 original signatories of the Montreal Protocol are:

  • Antigua and Barbuda
  • Australia
  • Austria
  • Belarus
  • Belgium
  • Burkina Faso
  • Canada
  • Chile
  • Congo
  • Denmark
  • Egypt
  • European Union
  • Finland
  • France
  • Germany
  • Ghana
  • Greece
  • Indonesia
  • Ireland
  • Israel
  • Italy
  • Japan
  • Kenya
  • Luxembourg
  • Maldives
  • Malta
  • Mexico
  • Morocco
  • Netherlands
  • New Zealand
  • Norway
  • Panama
  • Philippines
  • Portugal
  • Russian Federation
  • Senegal
  • Spain
  • Sweden
  • Switzerland
  • Thailand
  • Togo
  • Uganda
  • Ukraine
  • United Kingdom of Great Britain and Northern Ireland
  • United States of America
  • Bolivarian Republic of Venezuela

Over the years, more countries signed up to become a party to the Montreal Protocol. Those who joined after the Montreal Protocol was enacted are:

  • Afghanistan
  • Albania
  • Algeria
  • Andorra
  • Angola
  • Antigua and Barbuda
  • Armenia
  • Azerbaijan
  • Bahamas
  • Bahrain
  • Bangladesh
  • Barbados
  • Belize
  • Benin
  • Bhutan
  • Plurinational State of Bolivia
  • Bosnia and Herzegovina
  • Botswana
  • Brazil
  • Brunei Darussalam
  • Bulgaria
  • Burundi
  • Cabo Verde
  • Cambodia
  • Cameroon
  • Central African Republic
  • Chad
  • China
  • Colombia
  • Comoros
  • Cook Islands
  • Costa Rica
  • Côte d’Ivoire
  • Croatia
  • Cuba
  • Cyprus
  • Czech Republic
  • Democratic People’s Republic of Korea
  • Democratic Republic of the Congo
  • Djibouti
  • Dominica
  • Dominican Republic
  • Ecuador
  • El Salvador
  • Equatorial Guinea
  • Eritrea
  • Estonia
  • Eswatini
  • Ethiopia
  • Fiji
  • Gabon
  • Gambia
  • Georgia
  • Grenada
  • Guatemala
  • Guinea
  • Guinea-Bissau
  • Guyana
  • Haiti
  • Holy See
  • Honduras
  • Hungary
  • Iceland
  • India
  • Islamic Republic of Iran
  • Iraq
  • Jamaica
  • Jordan
  • Kazakhstan
  • Kiribati
  • Kuwait
  • Kyrgyzstan
  • Lao People’s Democratic Republic
  • Latvia
  • Lebanon
  • Lesotho
  • Liberia
  • Libya
  • Liechtenstein
  • Lithuania
  • Madagascar
  • Malawi
  • Malaysia
  • Mali
  • Marshall Islands
  • Mauritania
  • Mauritius
  • Federated States of Micronesia
  • Monaco
  • Mongolia
  • Montenegro
  • Mozambique
  • Myanmar
  • Namibia
  • Nauru
  • Nepal
  • Nicaragua
  • Niger
  • Nigeria
  • Niue
  • North Macedonia
  • Oman
  • Pakistan
  • Palau
  • Papua New Guinea
  • Paraguay
  • Peru
  • Poland
  • Qatar
  • Republic of Korea
  • Republic of Moldova
  • Romania
  • Rwanda
  • Samoa
  • San Marino
  • Sao Tome and Principe
  • Saudi Arabia
  • Serbia
  • Seychelles
  • Sierra Leone
  • Singapore
  • Slovakia
  • Slovenia
  • Solomon Islands
  • Somalia
  • South Africa
  • South Sudan
  • Sri Lanka
  • St. Kitts and Nevis
  • St. Lucia
  • St. Vincent and the Grenadines
  • State of Palestine
  • Sudan
  • Suriname
  • Sweden
  • Switzerland
  • Syrian Arab Republic
  • Tajikistan
  • Timor-Leste
  • Tonga
  • Trinidad and Tobago
  • Tunisia
  • Turkey
  • Turkmenistan
  • Tuvalu
  • United Arab Emirates
  • United Republic of Tanzania
  • Uruguay
  • Uzbekistan
  • Vanuatu
  • Vietnam
  • Yemen
  • Zambia
  • Zimbabwe

At recent, all UN member states, as well as the Holy See and Palestine who are not UN members, are participants to the Montreal Protocol. From the original 46 countries, the member parties are now 198.

Montreal Protocol Amendments

Just like any other global treaty or law, the Montreal Protocol had various amendments over the years to keep it updated and meet the pressing needs and concerns over time. As of this time, there are five amendments made to the Montreal Protocol:

The London Amendment focused on adjusting and strengthening the original measures crafted to control the ODSs listed by the Protocol, particularly CFCs, carbon tetrachloride, and halons, and phase them out by 2000 and 2010 in developed and developing countries respectively. It also introduced methyl chloroform to the list of controlled ODSs, promoted continuous research on its legal, technical, and scientific issues and established the Multilateral Fund for developing countries to meet their goals.

The primary purpose of the Copenhagen Amendment was to adjust the timelines set so that the phasing out of the known ODSs will occur much earlier. It also set the phaseout of HCFCs to 2004 in developed countries and adjusted the phaseout (in developed countries) of CFCs, carbon tetrachloride, halons, and methyl chloroform to 1996.

Supplementing the Copenhagen Amendment is the Montreal Amendment that pushed for the phaseout of HCFCs in developing countries. Methyl bromide should follow suit in developed countries in 2005 and in developing countries by 2015.

The Beijing amendment was later introduced to have stricter control over HCFCs, particularly in terms of their manufacture and trade. It also added bromochloromethane to its list of ODSs and set its phaseout goal to 2004.

After discovering that the supposedly less harmful HCFCs are in fact worsening climate change, the Kigali Amendment sought its phasing down. It was later identified as a greenhouse house, and its manufacture and use may not contribute to the depletion of the ozone layer but it does affect the climate.

While only five amendments were made so far, it will not be surprising if the parties meet up again in the future to discuss further amendments, particularly with the scheduled phasing out of ODSs. These changes were necessary to meet the goals set and to make much-needed adjustments, depending on the severity of the ozone layer depletion.

How Does the Montreal Protocol Work?

Despite undergoing multiple amendments over the years, how the Montreal Protocol works remains essentially the same. That is, it promotes the phasing out of ODSs in both developed and developing countries according to the set timelines and in a stepwise manner.

These timelines vary according to the ODSs and the country involved, but they follow a general pattern:

  • The first step involves halting the production of these ODSs. By freezing its manufacture, member parties expect the ODSs levels to be lower compared to the reference levels set. These reference levels can either be the average level in a specific year or periods, depending on the ODSs.
  • Minus percentages relative to these reference levels should be reached by the dates set. The number of these targets will also depend on the specific ODSs; some may have only one target minus percentage by a certain year, while others may have multiple targets over the years.
  • Following the pattern of decline in ODSs levels, the phaseout dates will be set.

To better understand the process, here is the set timeline for HCFCs for developed countries, with the average level of 100% CFCs and 2.8% of HCFCs in 1989 used as the reference level:

  1. Freeze its production by early 1996
  2. Reduce it by 35% by 2004
  3. Reduce it by 75% by 2010
  4. Reduce it by 90% by 2015
  5. Complete phaseout by 2020

By setting a timeline, all member parties are expected to meet these respective deadlines to meet their goals. To track the progress of individual countries, the Protocol mandates them to provide accurate progress reports annually. This not only monitors each country’s compliance and progress in terms of the schedules set, but it also monitors the overall effectivity of the Protocol in prohibiting these ODSs.

Member parties acknowledge that developing countries will likely experience difficulties meeting the Protocol’s goals compared to developed countries, that is why they decided to establish the Multilateral Fund for the Implementation of the Montreal Protocol. This fund serves as financial assistance to help these developing countries meet the schedules set and is replenished every three years.

These member parties also have annual meetings to check on the overall progress in terms of meeting its objectives, keep themselves updated with the latest scientific findings, and come up with ways to make all participants be more compliant and meet their respective timelines.

The overall process is straightforward, but meeting the goals of the Montreal Protocol involves a lot of work. In case a member party fails to meet its target or non-compliance, they have come up with measures that can be done. Depending on the case, these can either be by providing the needed assistance, issuing a reprimand or caution, or suspension. The purpose of these measures is to ensure compliance of member parties to the protocol.

Why Was the Montreal Protocol Successful?

Among all environmental laws created so far, the Montreal Protocol is unanimously considered as the most successful. This claim can be justified by various scientific evidence, but there is no evidence more decisive than the shrinking of the ozone layer hole.

If you recall, this hole was the result of the ODSs present over the years. These ODSs are the main focus of the Protocol since they see it as the main source of the depletion of the ozone layer. By prohibiting the production and consumption of the ODSs, they believe that the ozone layer will eventually recover, which is what is happening now.

The continued success of the Protocol is due to multiple factors, such as:

  • Cooperation between all member parties. Because they had a very specific goal backed by ongoing scientific research, it was easier for them to come up with actual solutions and ways to enforce them. They also encouraged the participation of key informants, which are the scientists, and this greatly helped them in decision-making.
  • Financial aid encouraged everyone to participate. There is a generally low expectation for low-income countries to fully participate in global treaties and laws due to financial constraints, but the Montreal Protocol begs to differ. By providing funds to these countries, it will enable them to meet protocol’s goals.
  • Awareness of the worst-case scenarios. There was widespread alarm with the discovery of the ozone layer, leading to a lot of misconceptions. In some way, these misconceptions also helped because it pushed people to take immediate actions to fix the problem. Finding out what the actual effects of ozone layer depletion are also helped because they realized that humans are not the only ones who will be affected; the situation will be that bad.
  • More freedom and less formality. Member parties were encouraged to participate and they also promoted flexibility. That is, they may have established the Protocol but there is leeway to make further changes to tailor-fit it in order to achieve their goals, hence the various amendments over the years.
  • Early identification of ODSs. Since they are aware which substances are destroying the ozone layer early on and as further research comes in, they can address them immediately and identify which ones need to be prioritized and phased out first.
  • Participation of various industries. Those who are known producers of ODSs and products that use them were more than happy to comply with the protocol because the ODSs they make or use were starting to become obsolete at that time. Finding more efficient alternatives meant they can save money in the long run.
  • Ordinary people also complied. Since people have a general understanding that the ozone layer hole is bad news, they were more active in preventing the worst-case scenarios they imagine from happening. Even basic information and misconceptions were enough to motivate them to participate in various programs that address ozone layer depletion.

All these factors were essential in ensuring the continued success of the Montreal Protocol. And since people were seeing the positive results of their actions, as well as experiencing negative effects of ozone layer depletion, they were even more motivated to reverse the problem.

Is the Montreal Protocol Still in Effect?

Given that we are getting consistently getting good news about the ozone layer lately, and the fact that it can heal itself over time, you may wonder if the Montreal Protocol is still in effect. After all, all these make it seem that there is already no need for the Protocol. The short answer is: yes. In fact, they recently added money to the Multilateral Fund for the developing countries.

While there have been major strides over the years, there is still much to be done, especially in developing countries. There are still some violators that produce ODSs, as well as products that require these ODSs, despite already prohibiting their production and use. These ODSs are also still present in the atmosphere, although they are now at generally lower levels.

The ozone layer may be quick to recover, but it is also quick to become damaged, especially since most ODSs remain in the atmosphere for years. While many ODSs are already banned, there are some that are still in the process of being phased out, which means they are still being used even in smaller amounts.

With the Montreal Protocol in place, it ensures that known ODSs will continue to decrease over time until it reaches the date when it becomes completely banned. Also, there is always a possibility that new ODSs may be discovered, just like what happened several times in the past, that is why constant monitoring is still needed. Early discovery makes early phasing out of these new ODSs possible.

Certain ODSs have already been banned, but there are still some ODSs whose phase-out dates are still decades from now. Because of this, the member parties still need to monitor each other’s progress in accordance with the Protocol. They may also need to make subsequent amendments and adjustments in the future, just like what happened in the past.

Until all these ODSs have been prohibited and the ozone layer hole has been completely repaired, you can expect the Montreal Protocol to remain in effect. It may mean more hard work for many, but the benefits for all mankind and the environment makes everyone’s efforts worth it.

We are already reaping the benefits of decades-long efforts, so there is no reason to stop now, especially because the ozone layer hole is still there, even if it is now smaller.

Welding: What is it, Definitions, Types, Processes

One of the most essential construction-related activities is welding. While there are other processes that can bind materials together, welding is the only one that can do so with metals. But most people are unaware that welding now goes beyond that definition, even already capable of binding wood and plastic. Also, not a lot of people know that it comes in different types.

The good news if you’re looking at becoming a welder – there’s currently a shortage in the industry for those possessing the skills we’re going to describe below.

Definition of Welding

For many, welding is defined as the process where two metals are joined together using extreme heat. Most people are aware of this definition, but they cannot distinguish it from other similar processes, namely soldering or brazing, and that pressure alone or combined with heat can also weld materials.

Not a lot of people are aware that welding is limited to bonding the same kind of material only. This means welding metal to metal is doable, but not metal to steel or any other combination of varying base materials. The same material should be used to ensure a strong weld; not doing so will prevent the two materials from being joined together permanently, which is the goal of welding.

And among welding, soldering, and brazing, welding produces the strongest joints when the welder does it correctly.

What is Welding?

In a nutshell, welding involves bonding two parent or base materials together that are of the same type using either heat or pressure, or even both. As a result, the two separate parent materials end up becoming one.

While welding usually involves only the base materials, filler materials can also be added when welding. Metal is added to the weld to strengthen the joint formed, while certain gases are used for shielding the weld to prevent oxidation or contamination that can weaken the joint formed.

High heat from a welding tool or machine, such as a blowtorch, is used to melt a part or section of the base material where the other one will be attached to. This softens that area or creates a molten pool of material where the material to be joined is attached to. This pool or soften material is set to cool down and once it resolidifies, the two materials are now joined to form one single material.

Pressure can also be used to weld materials together. This pressure alone may be enough to successfully weld the materials involved, or this pressure is used together with the heat generated by the pressure exerted over the base materials that need to be joined together.

Types of Welding

Contrary to what most people think, welding is not just about using a welding machine to join two metals together. In fact, there are different types of welding present, which are listed below:

  • Stick Welding – also known as the Shielded Metal Arc Welding or SMAW, it is named as such because the use of welding rods or sticks is essential for welding. These rods consist of the filler material that binds the metals and flux that aids in the binding process of the molten metals and at the same time protects them. Stick welding considered the most popular in developing countries due to its low cost, despite the weaker weld produced.

Stick welding is used in a variety of applications and industries, such as construction, aerospace, shipbuilding, marine, petroleum, nuclear, field repair, mining, structural welding, steel fabrication, and manufacturing.

  • Metal Inert Gas or MIG Welding – the second most popular type, the Gas Metal Arc Welding or GMAW technique involves the use of a welding stick or gun where an electrode current-connected consumable wire passes through. It forms an electric arc that produces enough heat to weld, while at the same time releasing a shielding gas. Wire welding has gained popularity due to its ease of use.

MIG welding is typically used in manufacturing, construction, automotive, and other industrial processes.

  • Tungsten Inert Gas or TIG Welding – this type follows the same process as that of wire or MIG welding, but it specifically involves the use of a non-consumable electrode containing Tungsten to create the required arc. TIG welding is now the most popular due to its ability to create a clean weld and high-purity, which results in a superior weld.

TIG welding is commonly used in doing repairs and creating art, as well as in the automotive and aerospace industries.

FCAW is best for doing general repairs, as well as in manufacturing, shipbuilding, underwater welding, and pipeline welding.

  • Submerged Arc Welding or SAW – while it also uses flux, this type differs from the flux-cored arc welding because welding occurs under a blanket of loose or granular flux. This results in fewer fumes and ultraviolet light, making it the safest type.

SAW is commonly used in industrial projects, especially in vessel and structural construction.

  • Electroslag Welding – typically used on thick metals that are non-ferrous, it involves melting flux to form a molten slag or pool where an electric arc will pass through. The pool will eventually reach the electrode to extinguish the arc.

Electroslag welding is also typically used for industrial purposes, such as castings, vessels, structures, ships, machinery, and pressure vessels.

  • Electrogas Welding – shares the same process as electroslag welding, but the electric arc present is deliberately left alone. Also, the arc is known to be positioned vertically and allows welding to occur in a single pass.

Electrogas welding is best for the construction of storage tanks, blast and chemical furnaces, vertical vessels, bridges, and ships.

  • Atomic Hydrogen Welding or AHW – slowly becoming obsolete, this type involves using two metal tungsten electrodes in an atmosphere containing hydrogen. This will cause the hydrogen to break apart and recombine, generating heat needed for welding.

AHW is suitable for any application where rapid welding is a must.

  • Carbon Arc Welding or CAW – known as the first type of arc welding, the CAW technique uses a carbon electrode that is non-consumable to heat the metals together, eventually welding them. This type is also becoming obsolete.

CAW is known for being suitable for use with copper, repairing cast iron parts with bronze, galvanized steel, and for thinner materials.

  • Energy Beam Welding or EBW – involves placing the parent materials in a total vacuum and shooting a beam of electrons to those materials at high velocity. The electrons fired are converted to heat that is needed to melt the materials and weld them. It has two specific types available: electron beam welding and laser beam welding

EBW is used for a wide variety of industries, namely aerospace, research, defense, medical, power generation, electronics, oil and gas, and automotive.

  • Gas Welding – best known as oxyacetylene welding or oxyfuel welding, fuel gases are mixed with pure oxygen to adjust the temperature of the flame of a welding torch used for welding. Gas welding is considered as one of the oldest types of welding.

Gas welding is normally used in manufacturing, as well as in the aircraft and automotive industries.

  • Resistance Welding – force is applied to both ends of the metal to be joined and an electric current is applied nearby to create the extreme heat required for welding. Various techniques of resistance welding include seam welding, spot welding, flash welding, upset welding, butt welding, and projection welding.

Resistance welding is best for industrial, aerospace, and automotive applications.

Among the different types of welding used, arc welding is the most widely used in various industries. Arc welding is a broad category that covers stick welding, MIG welding, TIG welding, flux-cored arc welding, submerged arc welding, electroslag welding, electrogas welding, atomic hydrogen welding, and carbon arc welding and is used in a wide variety of industries. All these require electricity to generate the arc required for welding.

Not a lot of people know that welding can also be done underwater, but only for specific types. Hyperbaric welding is a specialized type that can be done via either wet welding or dry welding. Wet welding often uses the stick welding type, with the bubbles produced by the flux acting as a shield to prevent electrocution of the welder. On the other hand, dry welding involves creating a hyperbaric chamber surrounding the area before welding following the chosen type.

Welding Processes

Aside from choosing what type to use, welders also concern themselves with choosing among the welding processes available to determine which one is most suitable for their project. Which process to choose mainly depends on the type of joint, whether edge, T, butt, corner, or lap, and the material to be joined together.

The welding processes available are broadly categorized into two: fusion welding and pressure welding.

Fusion welding is the process many are most familiar with since it involves heat to weld materials together. The edges of the parent material are heated so that when they cool down and harden, they are already joined together. Using filler material and inert gases are optional, and no pressure is needed to weld these materials together. The different types mentioned above fall under fusion welding.

It should be noted that fusion welding requires at least one of the parent materials to have a solid-state solubility, as this determines their weldability. If the parent material is non-soluble in the solid state, it will require a soluble material for welding to be possible.

On the other hand, pressure welding involves the use of external pressure to the joints to be welded. Producing these joints are done through either solid state welding, which involves adding pressure at temperatures below the materials’ melting points, or fusion state welding that requires doing so at above melting point temperatures.

Unlike fusion welding, pressure welding requires that the joints or ends of the material are free of contaminants, particularly oxides and films that are non-metallic in nature. These joints should be completely clean to ensure that the joint made between the materials is the strongest possible.

Pressure welding is normally used when the materials involved are known for being ductile or whose ductility increases as the temperature also increases. Some examples are:

  • Cold pressure welding – welds materials, specifically for electric components, wires, and sheets, without requiring heat to do so.
  • Explosive welding – necessary if the parent materials are dissimilar metals whose joints require welding, such as for cladding. This solid-state process involves using explosives to weld materials together. These explosives cause one of the materials to accelerate toward the other and weld them together.
  • Friction welding – two metals are rubbed together and the friction between them generates the heat needed to weld them. This is also suitable for dissimilar metals, but it can also be used for similar ones
  • Inertial welding – similar to friction welding, but it involves rotating one of the materials to the other, with the latter remaining stationary. This is ideal for alloys with high strength
  • Induction welding – mostly used for pipes and tubes, it involves using an induction coil that electromagnetically produces the heat required for welding. The tube or pipes involved pass through the coil at high speeds, which causes heating on its edges and are squeezed together to form a seam that joins them together.
  • Percussion welding – involves using quick electrical discharges to form an arc that has a high temperature. This discharge causes pressure to be applied to the materials involved, welding them together. This is also suitable for joining dissimilar metals
  • Ultrasonic welding – vibrations are produced through sound waves at high frequency, and these cause the materials to bond together. This is normally used for welding thin sheets and plastics.