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Guidance Notes on Health Hazards
in Construction W
in Construction ork

This guide is prepared by the
Occupational Safety and Health Branch
Labour Department
This edition February 2004
T h i s g u i d e i s i s s u e d f r e e o f c h a r g e a n d c a n b e o b t a i n e d f r o m o f f i c e s o f t h e
Occupational Safety and Health Branch, Labour Department. It can also be downloaded
from Addresses and telephone numbers of
the offices can be found in the website or by telephone
2559 2297.
This guide may be freely reproduced except for advertising, endorsement or commercial purposes.
Please acknowledge the source as “Guidance Notes on Health Hazards in Construction Work”,
published by the Labour Department.

Guidance Notes on Health Hazards
in Construction W
in Construction ork

Principles of Health Protection
Health Hazards
Further Reading
Further Information

Workers in a construction site may be exposed to various hazardous
substances and physical agents, e.g. asbestos, lead, silica dust, organic
solvents, sewer gases, welding fumes, radiation, noise and vibration.
Excessive exposures to these substances/agents may result in acute
injury, chronic illness, permanent disability or even death. Loss of
concentration at work and fatigue arising from poor health conditions
may increase the risk of accidents.
Construction work is featured by high labour turnover, constantly
changing work environment and conditions on site, and different types
of work being carried out simultaneously by several contractors.
These features would further increase the health risks of workers.
Principles of Health Protection
Hazard Identification
To prevent health hazards at work, all possible health hazards that may be encountered should be
identified before commencement of construction work. The health hazards at a construction site may
come from the hazardous substances used or those already present on site. The environmental conditions
may also create additional health hazards. These factors should also be identified, for example, heat
and noise. The information for hazard identification can be obtained from the equipment and material
supplier, site owner and principal contractor. If such information is not available, then a contractor
should take actions to identify unknown substances or seek assistance from a specialist if necessary.
Risk Assessment
Risk assessment is the process to look at the
conditions workers are exposed to the hazards
and determine whether the hazards likely to cause
any harm to the workers. Assessment of risks
may be made by considering factors such as:
• the air concentration of fumes, vapours and dust
generated from the work processes;
• the effectiveness of ventilation on site to control
the air contaminants;
Health risks at work should be assessed to ensure that the workers are
adequately protected.


• the likelihood of skin or eye contact with corrosive/irritating substances;
• the exposure of the workers to hazardous physical agents, e.g. noise, heat and radiation;
• the ergonomic factors, e.g. repetitive tasks and manual handling.
Both the immediate risks, e.g. being overcome by fumes in a confined space, and the long term health
risks, e.g. skin cancer from prolonged contact with pitch, should be assessed. The assessment should
be reviewed when new hazardous substances and physical agents are used and when there is a significant
change in the working environment.
When health hazards are identified, the first step is to try to eliminate them completely. It means
• Doing the job in a different way, for example, instead of using acids or caustic soda to unblock a
drain, use drain rods; or
• Using a substitute, for example, instead of using spirit-based paints, use water-based ones which are
generally less hazardous. However, always check that one hazard is not simply replaced by another.
If prevention is not practicable, the next step is to try to control the risk. The control methods may
• ensuring adequate ventilation in the working area;
• using as little hazardous substances as possible;
• applying local exhaust ventilation to particularly hazardous
processes, e.g. rock cutting and grinding and welding;
• using water suppression to control dust emission;
• segregating hazardous process so that workers not directly
involved are not affected;
• administrative measures, like providing sufficient safety
and health training, instructions and information to the
workers, appropriate supervision, good personal hygiene
and good housekeeping.
Provide exhaust ventilation to work areas where natural
ventilation is insufficient.


Personal Protective Equipment
If, and only if, exposure cannot be adequately
controlled by any combination of the measures
already mentioned, personal protective
equipment should be provided. These may
take the form of:
• respiratory equipment for protection against
dusts, vapours or gases;
• protective clothing, such as overalls, boots
and gloves for protection against irritating and corrosive substances, abrasion and vibration;
• eye protectors for protection against chemical splashes, such as goggles or face visors.
The personal protective equipment should be selected with care. A personal protective equipment
programme, including selection, maintenance, user training and supervision, should be set up to ensure
the effectiveness of the personal protective equipment.
Medical Surveillance
Medical surveillance is basically a system of
monitoring the health status of workers
engaged in hazardous occupations. The
objective is to detect early signs of illness so
that intervention may be taken to prevent
permanent health damage. This is particularly
useful for occupational illness with long latent
period, like silicosis and occupational
Workers engaged in hazardous occupations should undertake pre-employment
and periodic medical examinations.

The examination should be done by a medical
practitioner with sound knowledge in
occupational medicine. It is recommended that the following occupations in the construction industry
should undertake pre-employment and periodic medical examination because they may have prolonged
exposure to a high concentration/level of hazardous substances and/or physical agents.

Hazardous Exposure
Decoration and maintenance worker
Excessive noise (85 - 89 dB(A))
Bar bender and fixer, bricklayer, leveller, plumber,
Excessive noise (85 - 89 dB(A))
plasterer, carpenter, labourer, etc.
Ground investigation operator/pneumatic driller/borer,
Excessive noise (? 90 dB(A))
excavating worker, concrete worker, mason,
earthmoving machinery operator
Metal worker, piling operator
Excessive noise (? 90 dB(A))
Solvent containing benzene
Carpenter (formwork)
Methylene-di-isocyanate (MDI),
Toluene-di-isocyanate (TDI)
Excessive noise (85 - 89 dB(A))
Asphalter, road worker
Tar, pitch, bitumen and creosote
Excessive noise (85 - 89 dB(A))
Surveying technician (land)
Asbestos worker
Compressed air worker, diver
Compressed air
Excessive noise (? 90 dB(A))
Welder, blacksmith
Excessive noise (85 - 89 dB(A))
Welding fumes
Lead, Cadmium, Manganese
On the relevant statutory medical examination requirements for construction workers, reference could be made
to the Factories and Industrial Undertakings Regulations, the Factories and Industrial Undertakings (Work in
Compressed Air) Regulations and the Factories and Industrial Undertakings (Asbestos) Regulation.

Health Hazards
Health hazards in the construction industry can be grouped under chemical hazards, physical hazards
and ergonomic hazards:
• Chemicals can affect the body via inhalation, ingestion, or skin absorption.
• Physical hazards include noise, heat, vibration and radiation.
• Ergonomic hazards include mainly manual handling of loads.
Silica dust
Silica is a major component of the earth's crust.
Besides, a lot of building materials, like natural
stone, bricks and concrete contain silica. Therefore
workers are widely exposed to it. Any process
involving breaking, crushing or grinding silica
containing materials will generate silica dust. The
workers at high risk include operators of pneumatic
breakers, drillers and masons.

Exposure to excessive dust for prolonged period can lead to silicosis, a disease with lung fibrosis
causing difficulty in breathing. The risk is highest in confined spaces with poor ventilation, for
example, caissons and tunnels. Water suppression is usually an effective and economic means to
reduce the dust level. If engineering control measures are not possible to control the dust to an
acceptable level, adequate and suitable respiratory protective equipment should be provided and worn
by workers at risk.
Lead dust
Lead dust may arise from handling materials containing lead or its compounds, such as removal of
leaded paint and handling of metallic lead. Lead fumes may arise from hot cutting and dismantling
tanks previously containing lead compounds. Excessive exposure may cause acute or chronic health
effects. Welders and flame cutting operators may be at high risk.
Contractors are required to assess the nature and degree of exposures to lead, to take appropriate
measures to control the exposure, to inform the workers of the risks involved and to provide washing
and changing facilities.
Asbestos dust
Asbestos can cause asbestosis (diffuse fibrosis of the lung), mesothelioma (cancer of the lining of the
chest and abdomen) and lung cancer. Smoking further increases the risk of lung cancer for those
exposed to asbestos.
Asbestos dust will be generated whenever materials
containing asbestos are disturbed. These materials
include sprayed asbestos coatings, thermal and acoustic
insulation materials, fire resistant walls and partitions,
asbestos cement sheets and flooring materials.
Demolition work on asbestos insulation and sprayed
asbestos coating can produce particularly high level of
dust. These materials should be removed by competent
asbestos contractors before commencement of demolition
All work involve asbestos and the required safety
precautions are regulated by the Factories and Industrial
Undertakings (Asbestos) Regulation and the Code of
Practice on Safety and Health at work with Asbestos.
Disposal of materials containing asbestos has to be carried
out in accordance with the Enviromental Protection
Asbestos containing materials should not be demolished without
Department requirements.
adequate worker protection.

Gases, vapours and fumes
Gases, vapours and fumes may be released
from a variety of processes, including:
• welding and flame cutting;
• using internal combustion engines and LPG
• burning of waste materials;
• painting - particularly paint spraying;
• using adhesive and thinners.
The harmful effects depend on the types, toxicity and concentration of the gas and vapour present in
the working environment. Some can overcome the worker quickly while others can have long-term
health effects. Adequate ventilation must be provided and suitable respiratory protective equipment
worn where appropriate.
Entry into confined spaces
In the course of work, if entry into confined space is required, extra precautions are necessary. Problems
encountered include oxygen deficiency and inhalation of toxic or inflammable gases like carbon
monoxide, methane, hydrogen sulphide, etc.
Entry into a confined space is regulated by
the Factories and Industrial undertakings
(Confined Spaces) Regulation. A safe system
of work should be established by the proprietor
or contractor responsible for the operation in
the confined space. The system should
include, but not limited to, a risk assessment,
appropriate safety precautions, use of personal
protective equipment, emergency procedures
and training.
Monitor for hazardous contaminants before entering a confined space.