The Atmosphere

The atmosphere is a layer of gases held in place by gravity directly above the earths surface.

Why is the atmosphere important?

The atmosphere has several important functions, all of which are needed to sustain life on earth. There are 4 major gases which make up air in Earth's atmosphere, they are Nitrogen (78%), Oxygen (21%), Argon (0.93%) and Carbon dioxide (0.04%). The sun radiates heat towards the earth, the earth the re-radiates the energy as long-wave infrared radiation. Gases like carbon dioxide then play a role in the absorption and retention of heat which originated from the sun. Greenhouse gases are vital to keep the earth at the perfect temperature to support life forms. Oxygen is also an essential gas, used by organisms in the process of respiration.

Another major function is protecting life forms from the harmful ultra- violet radiation from the sun. This is achieved by the small concentrations of ozone in the upper reaches of the stratosphere. Lastly, the atmosphere is where the development of clouds occurs. Clouds are collections of millions and trillions of tiny water droplets and are the structures responsible for all essential precipitation.

Air Pollution

Air pollution is described as the release of harmful chemicals and gases into the atmosphere. These substances cause catastrophic affects on the environment, to human health, biodiversity and the climate.

Air pollutants are split into two integrated yet separated categories, greenhouse gases and criteria pollutants. Greenhouse gases are responsible for causing climate change while criteria pollutants are responsible for the deterioration of peoples health.


Both greenhouse gases and criteria pollutants are for the most part released by the same sources, however, the targets of their effects differ.

Depending on the businesses and industries found in your area, emissions and air quality may vary. If you are based in South Africa and would like to know what the air quality in your area is like, head to SAAQIS for more information. This site is also a platform available for you to report any facilities you may think are emitting hazardous amounts of air pollution.

Criteria Pollutants

Criteria pollutants are responsible for the deterioration of health in individuals. They cause respiratory problems and other health complications. Criteria pollutants such as sulfur dioxide and nitrogen oxides also cause acid rain which is harmful for the environment.

Greenhouse Gases

Greenhouse gases are responsible for increasing the earths global warming potential and inducing climate change. Their increased concentration in the atmosphere leads to the increased absorption of heat which originates from the sun.

Criteria Pollutants

There are seven types of criteria pollutants. These are gases and particles that are emitted into the atmosphere and are harmful to human health. They include gases like nitrogen dioxide, ground level ozone, carbon monoxide, lead and benzene, sulfur dioxide as well as particulate matter. These are the only pollutants with national air quality standards (permissible amounts that may be emitted into the air).

Nitrogen Dioxide

Nitrogen Dioxide (NO2) falls into a group of highly reactive gases known as nitrogen oxides (NOx). Other nitrogen oxides include nitrous acid and nitric acid. NO2 is emitted through the burning of various types of fuels. Sources include cars, trucks, buses, power plants, and off-road equipment.

NO2 when at high concentrations in the atmosphere can cause irritation in the airways of the respiratory system upon inhalation. Respiratory diseases such as asthma may become aggravated causing symptoms such as coughing, wheezing or difficulty with breathing. These symptoms and side effects could lead to increased hospital admissions and an increased susceptibility to respiratory infections.

Lead and Benzene

There are many sources that release lead into the atmosphere, a major source being ore and metals processing ( the lead concentrations are the highest around lead smelter) others include aircraft that run on aviation fuel containing lead, waste furnaces and lead-acid battery manufacturers.

If lead is taken up by the body it begins to accumulate in the bones and can also cause severe damage to the central and peripheral nervous systems. Other parts of the body that are affected are the reproductive system, the kidneys and the heart. Lead exposure to infants and young toddlers has also shown to decrease IQ levels as well as cause learning disabilities.

Benzene on the other hand is a volatile, organic compound which is emitted mostly from the petrol chemical industry, vegetation fires and cigarette smoke. Benzene has shown to cause damage to the immune, reproductive and central nervous systems. Long- term exposure to this chemical has also proven to cause cancer.

Carbon Monoxide

CO is a colorless, odorless gas. Carbon monoxide can be fatal to humans in large quantities. The CO molecules prevent the body from being able to take up as much oxygen from the air and can cause strain to the heart or suffocation. CO is at its most dangerous in enclosed spaces (indoors). The greatest sources of CO are cars, trucks and other vehicles or machinery that burn fossil fuels. Household items such as gas burning stoves can also release CO.

Sulfur Dioxide

There is in fact an entire group of sulfur oxides (SOx), all of which are toxic and harmful to humans. SO2 occurs in the greatest concentrations. Another sulfur oxide includes SO3 which is of less concern but the presence of which is usually determined by that of its more significant counter part. SO2 is primarily emitted by sources of fossil fuel combustion at power plants as well as in industrial processes. Sulfur dioxide is a colorless gas that has an unpleasant odor and is one of the primary compounds which makes up acid rain, consequently, it is also harmful to the environment. Exposure to SO2 can harm the human respiratory system by making breathing difficult. Respiratory issues such as asthma are worsened by the presence of sulfur oxides.


Ozone consists of three oxygen molecules. Depending on where it is found ozone can be both beneficial or harmful. Beneficial ozone is found in the upper reaches of the atmosphere (the stratosphere) and it is responsible for protecting us from harmful ultraviolet radiation from the sun. Harmful ozone however is found at ground level (it is the main component of smog) where even in small concentrations it can be harmful to human health.

Particulate Matter

Particulate matter (or PM) describes the mixture of solid particles and liquid droplets found in the atmosphere. These particles include dust, dirt, soot, or smoke. These particles can be macroscopic (visible with the human eye) or microscopic ( a microscope is needed to see them). Particulate matter pollution is categorized by size, for example PM10 describes particles with diameters that are 10 micrometers or smaller. PM2.5 however describes particles with diameters of 2.5 micrometers or smaller, these are extremely fine. These pollutants can be detrimental to an individuals health as they make their way into the lungs and bloodstream after being inhaled. Particulate matter pollution varies in size, shape and chemical composition. The sources of these pollutants also vary significantly, some examples of such sources include construction sites, unpaved roads, soil erosion of fields, smokestacks and wild fires. These particulates also originate from complex chemical reactions in the atmosphere, the chemical components of which are emitted by power stations, industries and vehicles.

Air Quality Monitoring

There are many different types of air quality control instruments that are used to measure the concentrations of any given pollutant in the atmosphere. In South Africa there are currently 94 air quality monitoring stations that have been set up by the National Ambient Air Quality Monitoring Network (NAAQMN). These stations are monitored and operated by the South African government. There are many non-governmental organisations that have their own stations as well. The data from these stations is used to ensure that the concentrations of certain pollutants do not exceed legal and health limits. These instruments are mainly used to measure pollutants such as carbon monoxide, sulphur dioxide, lead, ozone, particulate matter and nitrogen dioxide.

Affects of Criteria Pollutant Emissions on People and Ecosystems

Click here to see interactive diagrams of these affects.


Greenhouse Gases

The Greenhouse Effect

Greenhouses are large glass structures that are ideal for growing plants all year round. Greenhouses make plant growth in the winter possible because heat from the sun is trapped inside the glass, so even on cold winter nights the temperatures within the greenhouse remain moderate and comfortable enough to keep plants alive. Similarly, greenhouse gases act as the glass of the greenhouse, they surround the earth in the atmosphere and are responsible for the absorption of energy in the form of long-wave infrared radiation from the earth. The greenhouse effect is very important as it ensures that temperatures at the earths surface are well within range to sustain all life forms. However, when there is an excess amount of greenhouse gases present in the atmosphere, there is more gas to absorb heat and this creates an enhanced greenhouse effect. It is this enhanced greenhouse effect that is responsible an increase in global atmospheric temperatures, bringing about global warming and climate change.

The Effects of Greenhouse Gas Emissions on the Environment

Increasing Average Global Temperatures

Increased atmospheric temperatures brought about by the enhanced greenhouse effect cause changes in the otherwise predictable weather conditions as well as fluctuations in rainfall patterns. There are six major effects of global warming and climate change, namely, droughts, floods, desertification, wildfires, a decrease in biodiversity and the melting of polar ice caps.


Areas surrounding major deserts suffer severely from these increases in temperatures and decreases in rainfall. As they become more and more dry they begin to replicate the climates of the deserts they lie close to (desertification). This means that they can no longer support the plant and animal life they could before and biodiversity decreases.

Melting Ice Caps

When temperatures rise, large glaciers attached to the continental Southern and Northern poles of the globe, begin to melt. The melting of this ice results in the rising of sea levels. Major cities that lie right on coast lines (all over the world) face issues like coastal erosion and flooding. Another issue that results from the melting of polar ice-caps is that there are animals that call these parts of the world home. Polar bears, Emperor penguins and snow leopards all suffer as their habitats are destroyed. Polar bears for example go hunting in search of food and then cannot find pieces of ice large enough to rest on, eventually they are too exhausted to swim and they drown.

Droughts and Floods

The fluctuations in rainfall patterns can result in floods or droughts. If rainfall becomes more frequent and increases above normal levels it causes flooding. In contrast if rainfall decreases below normal levels it causes droughts. Places like Durban have struggled with flooding while Cape Town faced severe water restrictions in 2018 as a result of drought. These natural disasters are bad for farmers and the agricultural industry as crops suffer and food becomes more expensive. Droughts and floods also affect plants and animals and can decrease biodiversity.


Wildfires are natural occurrences, however they can be started by human activities too. When temperatures increase near areas that have lots of plant life and thick vegetation fires start and spread a lot quicker and become increasingly more dangerous. These fires destroy buildings, plants and even animals that cannot escape. Examples of places where wildfires have caused large amounts of damage are in California, the Amazon and Australia.

Sources of Air Pollution

What is the South African government doing about air quality?

South Africa has had strict rules and regulations regarding air quality since 2004 when the Air Quality Act was established. The enforcement of these rules and regulations falls upon the Minister of Environmental Affairs. Since 2004 many framework and management strategies have been rolled out in governments attempts to improve air quality in South Africa. Ozone depleting substances have been phased out, ambient air quality standards for seven pollutants have been established and emission limitations have been imposed on large and small scale industries. These are just a few of the strategies that government has implemented. These are however ongoing attempts to improve air quality and environmental impacts, for example President Cyril Ramaphosa in 2019 signed a Carbon Tax Act into law. This act charges greenhouse gas emitters for the quantity of gases they release into the atmosphere in a year.

What are NGO's doing about air pollution?

There are many influential NGO's that are also involved in trying to improve air quality not only in South Africa but around the world. For example The World Health Organisation is heavily involved in the implementation of air quality legislation all over the world and has labelled air pollution as the single biggest environmental health crisis of our time. As an NGO your priorities include education and advocacy. Education because NGO's make it their responsibility to make the public and influential members of society aware of the issue they are supporting. Advocacy involves trying to get government to pass laws and respond to the issues you think are important, this could include anything from organizing peaceful protests to getting people to sign a petition.


Using Sustainable Energy Sources

Sustainable energy sources produce electricity and power without the use of fossil fuels. There are several types that have been implemented all over the world to decrease air pollution from the production of electricity. Because criteria pollutants and greenhouse gases are both emitted from the same sources, by using sustainable energy options you decrease the negative affects on both the environment and on peoples health.

Solar power

Solar panels harvest energy from the sun and convert it into a more useful form such as electricity. Photo-voltaic systems are used to create electricity and concentrated solar power is used mainly for thermal energy needs. This energy source is sustainable because no damage is inflicted on the environment, and sunlight is easy to come by. This, however, would not be an effective solution for areas that are overcast or which receive little sunlight throughout the year.

Wind Power

Wind power is most effective in places that experience high wind speeds and gales on a regular basis. Huge blades are positioned on poles which extend relatively high up into the atmosphere (these are known as wind turbines), the wind then turns these large blades creating mechanical power which powers electrical generators. Places where many of these turbines are found together are known as wind farms. Wind farms do to some extent disadvantage the environment as they require large pieces of land, more land than an otherwise conventional coal burning power station.

Hydro Power

Hydro means water, therefore hydro power refers to energy or electricity generated by falling or fast- running water. This form of energy generation has also been used to power irrigation systems as well as many other kinds of equipment. These power stations enormously reduce the amount of emissions released into the atmosphere. In order for hydro power stations to be established, dams need to be constructed. Dams are created by building a wall somewhere along a rivers course, this means that water that would normally flow downstream is now trapped behind a dam wall. This can be damaging to the environment because it can often lead to droughts, floods and decreased biodiversity for the areas surrounding the river downstream.

Introducing Legislation

By getting governments involved, legislation can be passed which places restrictions on the amount of greenhouse gases and criteria pollutants industries are allowed to emit. This is implemented by monitoring industry emissions and if facilities exceed the given restrictions they are then heavily fined. In many countries companies pay tax based on the amount of carbon dioxide they emit into the atmosphere (carbon tax), this is to encourage companies to find more sustainable ways to produce products.

Finding Alternative Fuels for Transport

Many companies have been working on cars that run on electricity instead of petrol (a fossil fuel). Even though in many cases electricity is still generated from burning fossil fuels, using electricity emits less carbon dioxide and pollutants into the atmosphere as apposed to running a car on petrol. These cars store energy in rechargeable batteries which then power electric motors. These battery powered cars are however only one of the many other alternative fuels that are being trialed and tested.

Plant More Trees and Vegetation

Plants and trees need carbon dioxide to grow, therefore by increasing the number of plants you increase the amount of carbon dioxide that is used up and converted into oxygen (a gas essential to all living things) during photosynthesis.

What can you do?

Save electricity

Turning lights off and saving electricity decreases the amount pollutants that are released into the atmosphere as less coal is burned to produce the power that is being wasted.

Use public transport or carpool

Public transport prevents every individual from needing to use their own cars, this decreases the amount of emissions into the atmosphere.

Plant trees

Plants and trees use carbon dioxide during the process of photosynthesis (how plants produce food and allow growth), this means that the more plants there are the more carbon dioxide will be consumed and the less severe the affects of global warming will be.

Use energy efficient light bulbs

Energy efficient light bulbs and appliances use less electricity and therefore they result in less emissions into the atmosphere from power stations.


By recycling you decrease the need for the extraction of raw materials and more energy to be used making products to replace the ones that have been thrown away.

Save water

Electricity is needed to purify and pump water to where it is needed. Saving water therefore helps decrease power station emissions.