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UNIT 1: WHERE DO WE STAND? THE STATE OF THE GLOBAL ENVIRONMENT
Ironically, the
world’s most
polluted cities
are also
important tourist
attractions or
‘hubs’.
• Particulate matter;
• Volatile organic compounds (VOCs), including hydrocarbons;
• Metals, mainly cadmium, mercury and lead.
Secondary pollutants are formed in the atmosphere through complex chemical
reactions. The most widely known is tropospheric or ‘ground-level’ ozone, which
is associated with urban smog. Nitrogen oxides and various hydrocarbons in the
presence of sunlight set off a process of reactions that produce photochemical
oxidants of which ground-level ozone is the most abundant.
Hydrocarbons + NOx + sunlight = O3 and photochemical smog
Air pollution is a major issue in all large urban areas worldwide. Apart from major
pollution incidents in many industrialised cities, Beijing, Manila, Bangkok, Mexico
City, Jakarta, Cairo, Buenos Aires, and Rio de Janeiro are joining the list of the most
polluted urban centres in the world.
Air pollutants likely to be found in all major urban areas are known as ‘criteria
pollutants’. The concentration of these varies with the level of industrial activity,
traffic density, climatic conditions, and the use of pollution-control technology. The
World Health Organisation, the European Union and the United States Environment
Protection Agency classify the following as criteria pollutants:
• Carbon monoxide;
• Nitrous oxide;
• Sulphur dioxide;
• Ground-level ozone;
• PM-10 (particulate matter of diameter < 10micrometres,
or black smoke);
• Lead.
Why Should the Tourism Industry be Concerned about
Air Pollution?
Ironically, the world’s most polluted cities are also important tourist attractions
or ‘hubs’. Cities are also the key product of the ‘weekend break’ and ‘short-stay’
holiday markets. More and more tourists are also becoming concerned about
urban air pollution. A 1997 EU ‘Eurobarometer’ survey showed that CLEAN AIE was
a key criterion in choice of holiday destination.
Reducing Air Pollution
A major focus of national air quality improvement strategies is the establishment of
air quality standards. There are two categories of air quality standards: standards
for ambient air quality, and standards for industrial air emissions.
Broadly speaking, the minimum limit for criteria pollutants would be 30 times
the ambient air standard. This limit accounts for the potential of an emission
to be diluted in the atmosphere. The ability of the surrounding air to dilute the
emission depends on such factors as prevalent air quality, emission density and
temperature, its flow rate, its source (including if it is stationary or mobile),
weather conditions, etc. Clearly, the more polluted the surrounding air, the lower
its capacity to dilute an emission.
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