Air quality is affected by economic activities which introduces pollutants into the
atmosphere that pose threats to human health and other life forms on earth. It furthermore
has the potential to change the climate with unpredictable, but potentially severe
consequences on a local and global scale. Because large bodies of air cannot be contained,
atmospheric pollution can only be controlled at its source.
At present there is no
comprehensive information on air quality or on the levels of emissions entering the
atmosphere from different sources. Major areas of concern are high levels of smoke and other pollutants
in poorer urban and rural households without electricity, and the impacts of the mining,
energy, mineral and petro-chemical industries on air quality standards (Environmental
Management Policy for South Africa, 1998).
Air pollution is a major environmental problem throughout the whole of South Africa. South
Africa derives 75,2 % of its energy from coal (a non-renewable resource), and most air
pollution problems thus result from mans pattern of energy use and production. The
rest of the energy comes from the following sources: 10,1% from crude oil, 9,8% from
renewable bagasse and wood, 3,1% from nuclear power, 1,6% from gas and 0,2% from hydro
power (Surridge, 1999).
The worst levels of air pollution in South Africa is found in the Eastern Highveld of
Mpumalanga (formerly the Eastern Transvaal). It covers an area of 30 000 km2 and
is home to ten ESKOM power stations, of which five are the largest in the world. The three
main power stations, Matla, Duvha and Arnot produce 860 tons of SO2 per km2
per year. The area also contains coal mines, Sasol petrochemical plants and other
industries. The major dust dome in South Africa is the Vaal Triangle to the south of
Gauteng (Tyson et.al., 1988).
polluted areas in Greater Johannesburg are the surrounding Highveld areas due to the
combustion of fuels for the generation of electricity, and Soweto, due to the burning of
coal for heating and cooking. In the winter, smoke and SO2 from the townships
are the main forms of air pollution, while vehicles and industries contribute to air
pollution throughout the year.
Factors influencing the pollution problem in South Africa and Greater
Johannesburg (Preston-Whyte & Tyson, 1988):
Unstable air circulates and dissipates pollutants in summer due to the
low pressure over the land.
In winter there is a high pressure over the country and pollutants are
trapped in stable air and not dissipated or transported elsewhere.
In the winter warm air rises from artificially heated cites or the
sides of valleys. Cold night air moves in below the hot air, and temperature thus rises
with height, called a low-level inversion. Pollutants are trapped in the cold layer by the
warmer air above and can not be dissipated. Low level inversion of hundreds of meters deep
commonly occur over Johannesburg in the winter.
Even if the pollutants manage to escape the low-level inversion they
still become trapped in high level inversions, which occur when cooler rural air moves in
beneath warmer city air. These inversions commonly occur over Greater Johannesburg at a
height of 1 200 1 600m above the ground.