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posted:: 12/20/2011
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Noise pollution

1. Introduction
Noise is an unwanted sound. Especially when very loud, it becomes a form of pollution
because it is irritating, causes mental stress and may even lead to temporary or permanent
deafness. The loudness (intensity) of sound is measured in decibels (dB). The scale goes
from 0dB which is total silence to 200dB which would be measured next to a rocket taking
off. Noise mainly comes from four sources: (a) aircraft noise, (b) road transport noise, (c)
construction and industrial noise, and, (d) neighborhood noise. The problem generated by
noise is not only that it is unwanted, but also that it negatively affects human health and
well-being. In Hong Kong, noise generated in working areas is controlled by the Labour
Department while noise generated in other places is controlled by the Environmental
Protection Department.
Sound Levels and Human Response

Common sounds Noise Level (dB) Effect

Rocket launching pad (no ear
180 Irreversible hearing loss
protection)
Carrier deck jet operation
140 Painfully loud
Air raid siren
Thunderclap 130
Jet takeoff (200 ft)
120 Maximum vocal effort
Auto horn (3 ft)
Pile driver
110 Extremely loud
Rock concert
Garbage truck
100 Very loud
Firecrackers
Heavy truck (50 ft) Very annoying
90
City traffic Hearing damage (8 Hrs)
Alarm clock (2 ft)
80 Annoying
Hair dryer
Noisy restaurant
Freeway traffic 70 Telephone use difficult
Business office
Air conditioning unit
60 Intrusive
Conversational speech
Light auto traffic (100 ft) 50 Quiet
Living room
Bedroom 40
Quiet office
Library
30 Very quiet
Soft whisper (15 ft)
Broadcasting studio 20
10 Just audible
0 Hearing begins
2. Sources
(a) Aircraft noise
The old airport (Kai Tak International Airport located in Kowloon City) is closer to
the city than any other major airports in the world. People living there are heavily
affected by the aircraft noise. Whenever take-off and landing, the noise produced can be
very damaging and annoying. Even at mid-night, the noise level is still around 80dB
which is sufficient to affect sleeping.

Landing of aircraft
[Source: http://home.netvigator.com/~thomast/pollution]

[Source: R. B. Bunnett & B. Massingham, New Geography, P. 299]
(b) Road traffic noise
Hong Kong is one of the busiest cities in the world. The traffic in Hong Kong is also
very busy. Its vehicle density is almost the highest in the world. Tall buildings, narrow
streets, buildings close to roads and highways are symbols of Hong Kong. Owing to
these, the road traffic contributes a significant portion in noise pollution. It is estimated
that the noise generated by traffic is louder than 70dB.
(c) Construction and industrial noise
Construction area is a major source of noise pollution. The noise level of road
drilling and piling operations can reach 110dB which is harmful to human. Workers in
the construction area use lots of engines or tools which generate much noise. Industrial
noise is usually confined in indoor environment. Workers in these areas who work for
eight hours a day or more are surrounded by noise levels well over 100 dB.
(d) Neighborhood noise
People will deliberately produce noise but at the same time, they complain others of
producing noise. Neighborhood noise is noise from residential buildings and public
places and is the type of noise pollution which receives most complaints in Hong Kong.
Examples of neighborhood noise pollution include noise from playing mahjong,
karaoke, loud music and conversation, doors slamming and baby screaming.

Noise complaints in Hong Kong 1995
[Source: R. B. Bunnett & B. Massingham, New Geography, P. 299]
3. Effects
Noise annoys and hurts people in both physiological and psychological ways. Problems
related to noise include hearing loss, stress, high blood pressure, sleep loss, distraction,
reduce in productivity of workers and a general reduction in the quality of life and
opportunities for tranquility.
4. Noise control in Hong Kong
(a) Noise Control Ordinance
The Noise Control Ordinance was introduced in 1989 to help reduce the noise
pollution. Its regulations cover noise generated from domestic premises and public
places, construction activities such as piling, industrial or commercial premises,
intruder alarm system installed in any premises or vehicle, individual items of plant or
equipment such as hand-held breaker and air compressor, and motor vehicles. One
example is to control traffic volume, vehicle mix and traffic conditions on roads. The
ordinance specifies noise standards for the sources and has been progressively
tightened to improve situation.

[Source: Environment Hong Kong 2001, P. 72]
(b) Planning ahead
Noise pollution has been exacerbated by limited space and poor planning in Hong
Kong. The old Kai Tak Airport and the West Kowloon Corridor are good examples.
The best solution is to have a good planning beforehand. Now, new towns are
designed with early input from the EPD. For example, in Tung Chung, roads are not
constructed right beside residents. They are separated by barriers and wide spaces.

West Kowloon Corridor
[Source: Environment Hong Kong 2001, P. 61]
(c) Environmentally friendly noise measures
Due to the bad planning in the past, some existing roads have been already
constructed close to people and create great disturbances to the nearby residents at
night. Some environmentally friendly solutions can be applied to reduce traffic noise.
These measures include the traffic management and pedestrian schemes. The traffic
management scheme has been implemented in 3 areas to forbid certain types of
vehicles from using some streets at night. Regarding the pedestrian scheme, vehicles
are not allowed to use some streets at a specified time. This scheme has been
implemented at Mong Kong and Causeway Bay. These measures can effectively
reduce noise pollution.

Traffic Management Scheme
[Source: Environment Hong Kong 2001, P. 70]

[Source: Environment Hong Kong 2001, P. 71]
(d) Other controls
The level or effect of noise can be minimized by several other ways. First,
workers in noisy working environment can be protected by wearing earplugs or other
ear protectors. Besides, noise can be absorbed and reduced by some materials. For
example, rubber or plastic compression seals, which are set around the door edges,
provide the best result of insulation when closing the door. Complete or partial
enslosure of the sources of noise is always employed in constructing roads. Barriers
can be used to change the path of noise and to produce a ‘shadow’ behind the barriers.
For example, placing a wall between the road and building.

Table 3 : Sound Insulation Materials for Enclosures
Material Thickness Surface Sound Transmission Loss
Density
(mm) (dB)
(kg/m2) 125Hz 500Hz 2,000Hz
Plastered Brick 125 240 36 40 54
Wall
Compressed 56 25 22 27 35
Strawboard
Acoustic Panel 50 27 19 31 44
(Sandwich type
steel sheet with
fibre glass)
Chipboard 19 11 17 25 26
Plaster Board 9 7 15 24 32
Plywood 6 3.5 9 16 27