Ozone depletion

The decomposition and production ofthe “good” ozone is a natural process. -The “good” ozone layer is located between 20 km and 40 km above the earth's surface and is very important to all life on earth, as it stops harmful radiation from the sun from reaching the earth's surface. However, humanactivities increase the amount of gases that a�ect this ozone layer, allowing harmful radia-tion to reach the earth's surface more easily. This can decrease plant growth and a�ect the aquatic life. Production of primarycrops, such as rice, corn and sun�ower can alsobe a�ected.

Smog

Smog is produced when air pollutants react in sunlight. In South Africa, smog can be seen as a brownish haze over cities. It reduces visibility, mostly in the mornings and late afternoons.As ground temperatures can be lower than those of the upper atmospheric layers, the smog can stay near the ground without spreading for numberof days. The city of Cape Town experiences such smog episodes, particularly during winter.

Global warming

Human activities are also contributing to the increase of greenhousegases in the atmosphere, such as carbon dioxide and methane.The build-up of these gases acts like a blanket that traps

heat close tothe earth's surface, increasing the temperature, and thus warming theearth. This disrupts the natural greenhouse effect

described earlier.

Acid rainWhen sulphur dioxide and nitrogenoxide gases come in contact with cloudsin the atmosphere, these gases canmake rain more acidic. This acid canbe deposited in the form of snow,fog or rain, with serious e�ects on theenvironment. Acid rain contaminatesdrinking water, damages buildings, bycorroding cement, and causes metals torust. It poisons soils, a�ects plant growth,and destroys plant leaves. It also harmsanimals, aquatic life, and other wildlife.

What are the effects of air pollution?

Health IssuesExposure to air pollution may cause various health problems. It can make one's nose burn, irritate the throat, make breathing difficult or irritate the eyes. This is a typical experience when one is cookingusing wood, coal or paraffin. Tiny particles of dust and smoke can get deep into a person's lungs and cause wheezing and coughing, especially to those people living with respiratory diseases. Other problems related to air pollution include asthma,cancer, heart diseases, skinirritations, headaches, dizziness,fatigue, stress, nervousdisorders and birth defects.

What is air pollution?Air pollution is the presence of any harmfulsubstances in the air which may negativelyaffect human, animal and plant life. Thesubstances that cause air pollution arecalled pollutants. Pollutants that arereleased directly by sources into ouratmosphere are called primary airpollutants. Examples include carbonmonoxide from vehicle exhausts andsulphur dioxide from the burning ofcoal. When primary pollutants reactwith each other and with other gasesin the atmosphere secondary airpollutants, such as ground level ozone,are formed. This is the “bad” ozone foundclose to the earth's surface and shouldnot be confused with the “good” ozonethat provides us with protection fromthe harmful ultraviolet radiation.Air pollutants can be gases, likecarbon monoxide, sulphur dioxide, oxidesof nitrogen and chemical vapours or verysmall particles, like dust, bacteria, viruses,plant materials, dead skin cells or piecesof hair.

The air around usWhen we breathe, we take-up oxygen through our lungs and breathe out carbon dioxide. Plants take up carbon dioxide and release oxygen into the atmosphere.Nitrogen is also needed by living organisms. It is soaked into soils, where bacteria use it to make food for plants. Thewater and gases in the atmosphere allowsun rays to reach the earth surface, whiletrapping the radiation released by the earth.The trapping of radiation, known as naturalgreenhouse e�ect, makes the layer of theatmosphere close to the earth surfacewarm enough to support life on earth.

Air is essential to all life. Naturally, the air consists of nitrogen, oxygen along with water droplets, �ne particles and a smallamount of other

gases such as carbon dioxide, nitrousoxide, methane, ammonia and argon.

All these gases are important as they help to support life on earth.

What are the sourcesof air pollution?1. Industrial plants that produce metals such as

aluminium and steel, refine petroleum, cement ormake other chemicals are among those that canproduce harmful pollutants. The constructionindustry is a major source of dust.

2. Power stations that produce energy byburning fossil fuels like coal, gas and oil, canemit sulphur dioxide, nitrogen dioxides andtiny par ticles such as ash.

3. Mining processes, such as mine dumps, ore handling,drilling, blasting and mine vehicles traffic travelling onunpaved roads, are mainly responsible for air pollutionin the form of dust, especially when the openmines are not covered with vegetation. Blastingoperations and unplanned burning of coal dumpsalso release gases such as nitrogen dioxide andsulphur dioxide.

4. Traf�c such as vehicles and aeroplanes, becausevehicle exhaust fumes from engines contain anumber of pollutants, including carbonmonoxide nitrogen oxides, and other compounds.

5. Agricultural activities,such as ploughing and harvestingactivities produce dust particles. The use of chemicals(e.g. fertilizers, pesticides and herbicides) on cropsto increase crop quality also contributes to airpollution. Large-scale burning to clear agriculturalfields also adds significantly to air pollution.

6. Household cooking and heating, especiallywhen using coal, wood and paraffin for cookingand space heating. This burning produces sulphurdioxide, carbon dioxide, carbon monoxide andparticles. This results in poor air quality and anunhealthy environment especially as most of theburning takes place in poorly ventilated rooms.

7. Refuse burning is very dangerous as the refuse is amixture of many different materials. For example, ifwe burn plastics, dangerous substances are givenoff that can harm our environment.

8. Other sources like chemical sprays; householdproducts such as tobacco and cigarette smoke;fumes from paint, hair spray, varnish, aerosolsprays; and many cleaning products we usein our homes.

In addition to man-made sources,large quantities of air pollutants arealso released from natural sources.These sources include:

1. Veld fires are common man-madeand natural sources of air pollution.They spread very quickly and release pollutants such ascarbon monoxide, nitrogen oxides, sulphur dioxide and tinyparticles into the atmosphere.2. Biological sources:There are significant quantities of pollutants that arereleased from natural sources such asvanimals, marshes and the soils. Other pollutantsinclude pollen grains.3. Volcanic eruptions producegases such as carbon dioxide,sulphurdioxide, hydrogen fluoride and ash particles. These eruptionsrelease the pollutants high intothe atmosphere, where they can travel long distances causing major disruptions.4. Wind erosion: Dust particles are released from soil surfacesduringstrong winds, especially wherethere are few plants and thesoils are dry e.g. in deserts.