About two-thirds of the world‘s population is expected to live in the cities by the end of 2020,
and, according to the United Nations, about 3.7 billion people will inhabit the urban areas some
ten years later. As cities grow, so do the number of buildings that characterize them: office
towers, factories, shopping malls, and high- rise apartments. These structures depend upon
artificial ventilation systems to keep clean and cool air flowing inside. We know these systems
by the term ‗air conditioning‘.
Although many of us feel that air-conditioners bring relief from adverse weather outside, they
pose many health risks. One such disease is called Legionnaires‘ disease, which was first
recognized in the 1970s. This was found to have affected people in buildings with air
conditioning systems in which warm air pumped out of the system‘s cooling towers was
somehow sucked back into the air intake, in most cases owing to poor design. This warm air was,
needless to say, perfect environment for growth of disease carrying bacteria originating from
outside the building, where it existed in harmless quantities. Cases of the disease are becoming
less with advanced systems designs and modifications to older systems, but many old buildings,
particularly in developing countries still need monitoring.
Ways in which air- conditioners work to ‗clean‘ the air can inadvertently cause health problems
too. One such way is with the use of an electrostatic precipitator, which removes dust and smoke
from the air. What precipitators also do, however, is emit large quantities of positive air ions into
the ventilating system. A growing number of studies show that overexposure to positive air ions
can result in headaches, fatigue and feeling of irritation.
Finally, it should also be pointed out that the artificial climatic environment created by air
conditioners can also adversely affect us. In a natural environment, whether indoor or outdoor,
there are small variations in temperature and humidity. Indeed, the human body has long been
accustomed to these normal changes. In an air-conditioned living or work environment, however,
body temperatures remain well under our normal body temperature. This leads to a weakened
immune system and thus greater susceptibility to diseases such as cold and flu.
(a) On the basis of your reading of the above passage make notes on it using recognizable
abbreviations (minimum four) wherever necessary. Use a format you consider appropriate.
Supply a suitable title. (5 marks)
(b) Write a summary of the passage in about 80 words.
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