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Summary: Air pollution in the heavily industrialised areas
of the Durban Metropolitan Area (DMA) is likely to
be contributing to respiratory diseases in residents, particularly children, the elderly, asthmatics and people with existing
breathing diseases. Depositions from polluted air can also
salinify and acidify soils and water with negative impacts
on plant and animal life. The emission
of greenhouse gases from the DMA is contributing
to global warming but at this point neither of these
effects are thought to be significant. Other impacts of poor
air quality include structural corrosion, poor visibility and general
nuisance but, again, these impacts are
limited.
Increased breathing
problems
The levels of
sulphur dioxide in the Durban South Basin's air at times exceed
national and WHO guideline values. These gases are absorbed
by humans through the inhalation of polluted air. They
impact more on children, the elderly, asthmatics and people
with chronic bronchitis. High levels of these gases can result
in aggravation of asthma and chronic bronchitis as well as
increased risk of respiratory tract infection in young
children. Individuals can experience wheezing, shortness of
breath and constriction of the bronchial tubes.
Acidification and
salination of air, water and soil
Sulphur
dioxide and nitrogen oxides, released primarily by industries
and motor vehicles react in the atmosphere to form secondary
pollutants such as nitric acid vapour, droplets of sulphuric
acid, and particles of sulfate and nitrate salts. These
chemicals descend to the earth's surface in wet form as acid
rain, fog and cloud vapour and in dry form as acidic
particles. This form of acid deposition is commonly called
acid rain. Acid deposition which reaches the earth's surface
can lead to increased salt and acid levels in water and soil.
Acid deposition has a number of harmful effects:
- It damages statues, buildings,
metals and car finishes.
- It can contaminate fish with toxic
substances, such as methylmercury. These substances can be
biologically amplified to high concentrations in food chains
and webs.
- It can damage foliage and weaken
trees.
- It and other air pollutants can
make trees more susceptible to stresses such as cold
temperatures, diseases, insects, drought and fungi that
thrive under acidic conditions.
- It can interfere with uptake of
calcium and magnesium from the soil by releasing soluble
ions, which damage tree roots.
- It can lead to excessive levels of
nitrogen in the soil. This can overstimulate plant growth
and increase depletion of other soil nutrients.
- It contributes to human respiratory diseases such as
bronchitis and asthma.
Global warming
Ozone and the emission of carbon
dioxide and methane which are 'greenhouse gases' contributes
to the warming of the earth and associated climate
change. It has been predicted that global warming will result
in a number of negative consequences for the DMA along with
the rest of the world. Global warming will lead to
a rise in sea-level which can result in the flooding of
coastal areas and erosion of the coastal zone. In Durban, this
could lead to a significant loss of beaches, as well as
beachfront property and infrastructure. Climatic changes may
affect the production of agricultural crops, as biogeographic
zones shift. Increased temperatures can lead to the spread
of diseases, as conditions become favourable for tropical
viruses presently found north of Durban. Other forms of
climatic change may include an increase in weather extremes,
such as hurricanes, floods and droughts. This could lead to
significant loss of life.
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