URBAN
URBAN
Energy and the
Environment
POLLUTION
POLLUTION
Monday, December 4, 2006
Hong Kong is fast becoming a walled city of skyscrapers,
adding to the pollution problem, writes Fun
Translated by Anvi l Ong
ALLED villages (圍村) are part of
Hong Kong’s historical rural architecture. But nobody ever imagined
that Hong Kong would so quickly
become a walled city surrounded by residential (住
宅) and commercial (商業) high-rise buildings along
the waterfront (沿海).
Perhaps several years ago your flat was in a
building facing the sea. You wouldn’t have considered that the sea would become land. Then, to make
things worse, high-rise buildings are constructed on
the land. It’s just like having someone cutting in
while you are queuing (排隊) -- your front view is
blocked. Even worse, it’s not just a building. It’s
block after block of buildings ... like good friends
standing shoulder to shoulder to form a wall.
Being fenced in by high-rise buildings is something peculiar to Hong Kong. When constructing a
building, a good architect will take into account the
geographical setting and city planning (城市規劃).
In many cities, buildings along the waterfront are
not allowed to block any mountain views. Even in
the older urban districts, there are restrictions on
the height and design of buildings. This is to give
the city aesthetic (美學的) uniqueness (特色). But in
Hong Kong, a place where money comes first, city
planning exists only in name. Since flats with a sea
view sell best, more and more land is reclaimed and
buildings get higher and higher.
W
Screen effect (屏風效應)
Types of air pollution
Photochemical smog
THERE are two categories of substance that can
cause air pollution. They are particles (微粒) and
pollutants (污染物). Particles are tiny solids or liquids such as dust (塵), steam (蒸氣), smoke (煙), ash
(飛灰), mist (薄霧) or spray (噴霧). Pollutants are chemicals like nitrogen oxides (氮氧化物), sulphur dioxide (二氧化硫), carbon monoxide (一氧化碳), ozone
(臭氧), etc.
Pollutants can be divided into primary (初級) and
secondary pollutants (次級污染物). Primary pollutants include carbon oxide, sulphur oxides, nitrogen
oxides and evaporative (揮發性) organic matter.
They are pollutants directly produced at sources
such as factories, power plants and vehicles.
Secondary pollutants are those that come from
primary pollutants through chemical reactions.
Ozone, formed by a chemical reaction between
some primary pollutants is an example of secondary
pollutants. In recent years in Hong Kong, the mist
that is often seen is another type of secondary pollutant. It is called photochemical smog (光化學煙霧).
PHOTOCHEMICAL smog consists of yellowish
grey mist which lowers visibility (能見度). The mist
mainly consists of nitric oxide (硝氧自由基) and
hydrocarbons (碳氫化合物) that are produced by
engines. That is to say, vehicles are one of the main
polluters in Hong Kong. In the process of forming
photochemical smog, the sun plays an important
role. Sunlight can increase the density of ions and
hence speed up the formation of smog. That is why
smog is denser (更濃厚的) on sunny days.
Photochemical smog brings about various
effects. Smog contains a lot of chemicals like
ozone, hydrogen peroxide (過氧化氫) ,
aldehydes (酮醛) and peroxosulphates (過氧醯硝酸鹽). They can
irritate the eyes, cause
coughs, breathlessness (氣 喘 ) ,
bronchial constriction (氣管收縮), respiratory system irritation (刺激呼吸系統) and even cause damage to the surface of different materials.
Smog speeds up the ageing (老化) of
plastics, and also damages leaf
tissues, causing them to
turn yellow.
Tsuen Wan air quality drops
TO improve the appearance of urban areas, Hong Kong is
going through urban reconstruction. Tsuen Wan is one of the
districts being reconstructed. But city planning in the district
has been criticised by environmental bodies (環保團體)
which pointed out that new buildings near the waterfront are
over 40 storeys high, blocking ocean winds from the southwest. This causes a screen effect and affects the air quality in
the region. They urged the Planning Department (規劃署) to
reconsider the district’s building density and design. They
hope the department will rescale developments to avoid
worsening air pollution in the district.
Tsuen Wan District Councillor Kwong Kwok-chuen (荃灣區
區議員鄺國全) said: “After the projects are completed, the population will increase and traffic will get heavier. Wind cannot
carry away vehicle exhaust gases creating a heat island
effect (熱島效應).
Think about it
• What is the source of air pollution?
• What can we do to improve air quality?
• Apart from air pollution, what other kinds of pollution do we
have?
• Can Hong Kong’s dense population be used as an excuse
for building high-rise buildings by the waterfront? How
should Hong Kong deal with its lack of land?
References
http://www.greeneducation.org.hk/focus/old.htm
http://resources.emb.gov.hk/envir-ed/c_index.htm
BEING surrounded by buildings not only ruins the
scenery, it also creates a screen effect, greatly slowing down the air movement in the region. As Hong
Kong’s air pollution gets more serious, the screen
effect contains polluted air in the region, aggravating (使惡化) the situation. The result is deteriorating
(惡化的) air quality.
As for air quality, it has reached the point where
pollution can be seen. It is more prominent (明顯) in
autumn and winter, when there is a lot of sunshine.
What one sees is not bright, clear blue skies. On the
contrary, it is a mass of whitish or greyish yellow
gas, just like a cloud of poisonous gas. What actually
is this mass?
E06
E07