Asbestos means crocidolite, amosite, chrysotile, fibrous anthophyllite or a mixture containing any of those minerals. Asbestos was used widely in a variety of building materials including floor tiles, ceiling tiles, asbestos-cement pipes or sheets, refuse chutes and fire resistant structures. The use of asbestos has been banned in Singapore buildings since 1989. However during removal, repair, dismantling, demolition, renovation, maintenance and alteration works, workers are exposed to asbestos.
Copyright © 2012 NTUC LearningHub Pte Ltd. All rights reserved 133 Asbestos fibres enter the body by inhalation of airborne dust or by ingestion and become embedded in the tissues of the respiratory or digestive systems. Exposure to asbestos causes occupational diseases such as Asbestosis (scarring and fibrosis of the lung tissues), Mesothelioma (cancer of the thin membrane lining of the chest, abdomen and gastrointestinal cancer) and Lung cancer. The symptoms generally appear after 20 years of exposure.
Legislation
Factories (Asbestos) Regulations R 3 Application
These Regulations shall apply to every process involving asbestos or any article composed wholly or partly of asbestos, except a process in connection with which asbestos dust cannot be given off.
R 4 Obligations under Regulations
Every contractor and every employer who is undertaking any process involving asbestos shall comply with the requirements of these Regulations.
R 5 Contractor, employer, etc, to ascertain whether process in factory involves asbestos Every contractor, employer, occupier and person shall take reasonable steps to ascertain whether any process undertaken in the factory involves asbestos or any article composed wholly or partly of asbestos. The steps to be taken shall include, where necessary, the analysis and examination of materials or articles involved in the process undertaken. R 6 Notifications
Before a person first begins to undertake any process involving asbestos in a factory, he shall give not less than 28 days’ notice of the process or such shorter notice to MOM. R 7 Exhaust ventilation
Exhaust ventilation equipment shall be
• provided except if it is safe for persons working in the factory
• kept in use to produce an exhaust draught which prevents the entry into the air of any workplace of asbestos dust.
• well maintained and inspected at least once a month,
• thoroughly examined and tested by a competent person at least once in every 12 months; The results of every such examination and test shall be signed by the person making or responsible and kept available for a period of two years after it is made.
R 8 Protective equipment
Where it is impracticable to provide exhaust ventilation, there shall be provided for each person suitable respiratory protective equipment; and protective clothing. All respiratory protective equipment and protective clothing provided shall
• be properly maintained.
• be used by the persons for whom they are provided
• be provided for the use of another person unless it has been thoroughly cleaned and disinfected since last being worn.
The user shall be fully instructed in the proper use of that equipment. R 9 Duty to keep clean
All machinery, apparatuses, work benches, other plant and equipment, all external surfaces of exhaust ventilation equipment, all floors, inside walls, partitions, ceilings, ledges and other internal surfaces of any part of a factory shall, so far as is practicable, be kept in a clean state and free from asbestos waste and dust.
Copyright © 2012 NTUC LearningHub Pte Ltd. All rights reserved 134 R 10 Cleaning by dustless method
The cleaning shall be by means of vacuum cleaning equipment so designed and
constructed and so used; or by some other suitable method so, that asbestos dust neither escapes nor is discharged into the air of a workplace.
R11 Cleaning where cleaning by dustless method is impracticable Protective clothing and suitable respiratory protective equipment
• shall be provided for and used.
• Shall be provided for the use of another person unless it has been thoroughly cleaned and disinfected since last being worn.
• Person shall be fully instructed in the proper use of that equipment.
Any surface on which asbestos waste or dust is deposited as a result of the carrying out of cleaning, not being a surface of the cleaning equipment used, shall be cleaned forthwith. R 12 Cleaning equipment
All cleaning equipment used for cleaning shall be properly maintained and have all external surfaces kept in a clean state and free from asbestos waste and dust.
R 13 Storage
All loose asbestos in a factory shall, when not in use, be kept in a room separated from any workplace in suitably closed receptacles, which prevent the escape of asbestos dust therefrom; and all asbestos waste in a factory shall, when stored, be kept in such receptacles.
R14 Distribution, etc
No loose asbestos or asbestos waste shall be despatched from or, as far as is practicable, received into a factory except in suitably closed receptacles, which prevent the escape of asbestos dust therefrom, or shall be distributed within a factory except in such receptacles or in a totally enclosed system of conveyance.
R 15 Marking of receptacles
All such receptacles shall be clearly and boldly marked with the words “Asbestos — do not inhale dust” or with other words in other languages having the same meaning and readily understood by those persons handling the receptacles or working in the factory.
R 16 Accommodation for, and use of, protective clothing and respiratory protective equipment
Suitable and separate accommodation in a conveniently accessible location shall be provided for the use of employees when putting on or taking off respiratory protective equipment and protective clothing provided and for the storage of such equipment and clothing when they are not in use. All protective clothing and respiratory protective
equipment which have been provided for the use of employees shall, when not required for use, be kept in accommodation for storage provided except when it is necessary for them to be removed for cleaning or replacement. So far as is practicable, the same protective clothing shall (until it becomes necessary to replace it) be available for use by an employee on each occasion on which he requires to wear it.
R 17 Cleaning of protective clothing
All protective clothing provided shall be washed and cleaned at suitable intervals. Adequate and suitable facilities shall be provided and maintained for the washing and cleaning of all protective clothing. The washing and cleaning of all protective clothing shall be carried out at the facilities provided.
R 18 Restriction on employment of young persons
No person under the age of 18 years shall be employed in any process or in a part of a factory into which asbestos dust from any such process carried on in the factory would otherwise be liable to escape; and in carrying out any cleaning.
Copyright © 2012 NTUC LearningHub Pte Ltd. All rights reserved 135 Risk Control
Elimination
• Asbestos has been eliminated from use. It can be found only in existing structures when it is being demolished.
Substitution
• Substitution of asbestos with other materials such as fibre glass. Engineering Control
• Barricades to prevent unauthorised entry into the work area. • Enclose the work area and seal off all outlets.
• Wet the surface to prevent release of fibres.
• Exhaust ventilation provided to prevent entry of asbestos dust into the workplace, maintained
• All loose asbestos to be kept in separate room
• Dispatched only in closed receptacles or in a totally enclosed system of transfer • Keep factory clean and free from asbestos waste and dust by vacuum cleaning
equipment or other methods preventing dust from escaping or discharged into the air • Suitable & separate accommodation for putting on and taking off protective clothing &
respiratory protection equipment Administrative Control
• Notification / Declaration of asbestos containing material during worksite registration when demolition, repair or re-decoration is carried out
• Information regarding the presence or absence of asbestos can be obtained from existing building plans.
• In case of doubt, suspected materials, such as roofing, ceiling, acoustic, fireproofing and insulation materials, should be sent to a competent laboratory for identification of asbestos.
• Medical examination of workers
• Remove non asbestos material from the work area to prevent contamination. • Implement safe work procedures
• Training on safe work procedure, respirators, RA • Follow legal requirements
• Exhaust ventilation to be inspected monthly and thoroughly examined by competent person every 12 months
• All receptacles shall be clearly and boldly marked with “Asbestos - do not inhale dust” • Storage of used protective equipment and clothing
• All protective clothing must be regularly cleaned in adequate and suitable facilities • No worker under the age of 18 years
• Establish asbestos work area
• Only workers who are doing the work are allowed to enter • No eating and drinking in the work area.
• Warning sign
• Provision of shower facilities • Housekeeping
Personal Protective Equipment
• Wear respirators with high efficiency particulate air (HEPA) filter. • Full body protective clothing
• Goggles
Copyright © 2012 NTUC LearningHub Pte Ltd. All rights reserved 136 6.10.2 EXPLOSIVE HAZARDS
Explosives are used for minor demolition works under controlled conditions. The hazards are
• Mishandling of explosives • Open lights
• Smoking
• Unsafe opening of packages • Drilling onto unexploded explosives • Forcing cartridges into holes
• Presence of personnel during blasting • Inadequate supervision
• Misfires
• Adverse weather
• Inadequate warning before the blast
The potential accident would be explosion resulting in injuries and fatalities. Legislation
WSH (Construction) Regulations
R 115 General duty on employer and principal
It shall be the duty of the employer or the principal carrying out work in a worksite which involves the handling or use of explosives, to comply with requirements 116, 117 and 118. R 116 Handling of explosives
Explosives shall not be handled or used except in accordance with the manufacturer's instructions and by or under the immediate control of a designated person with adequate knowledge of the dangers connected with their use. Reasonably practicable steps shall be taken to ensure that, when a charge is fired in a worksite, all persons are in such positions which do not expose them to risk of injury from the explosion or from flying materials caused by the explosion.
R 117 Smoking, open lights, etc.
Smoking, open lights and flame or spark producing devices shall be prohibited in or around the explosive magazine or storage enclosure. Appropriate warning signs of the prohibitions, understood by persons involved in the work relating to the handling or use of explosives, shall be posted and maintained at every place where the explosives are kept or stored. R 118 Opening packages
Packages of explosives shall not be opened at any point less than 15.5 metres distance from any explosive magazine. Metallic instruments shall not be used for opening packages of explosives in a worksite.
R 119 Deepening holes
No drilling of holes shall be carried out if the hole has at any time contained explosives. R 120 Size of holes
Any drilled hole to hold any cartridge of explosives shall be of sufficient size. Cartridges of explosives of the proper size shall be selected so that every cartridge can be easily inserted to the bottom of the drilled hole without forcing or ramming.
R 121 Removing cartridge wrappers
Dynamites are not removed from their original wrappers before being loaded into the bored holes.
Copyright © 2012 NTUC LearningHub Pte Ltd. All rights reserved 137 R 122 Loading near other operations
The loading of holes with explosives shall be carried out under the direct supervision of a blaster. It shall not be carried out within dangerous proximity to drilling or any other operations in the worksite.
R 123 Loading and tamping
Only a hardwood rod free from any metal part is used for loading and tamping of explosives.
R 125 Warning and retreat
Before the firing of any blast, a warning distinctly audible to all persons shall be sounded within the danger zone. No blast shall be fired while any person is in the danger zone. When the warning is sounded, all persons within the danger zone shall retire to a safe distance or to a safe shelter.
R 126 Return to blast area
No person shall return from such safe distance or safe shelter until permitted to do so by the blaster as announced by audible or visible signal.
R 127 Misfires
When there is a misfire of any blast, every person in the danger zone shall retire to a safe distance or a safe shelter. No person, other than a person appointed to dispose misfired charges, shall enter the danger zone until the misfired charge is disposed of. The blaster who fired the blast shall examine the blast area for evidence of misfired charges
immediately following the blast; and to immediately report any misfire to the
designated person. The designated person shall appoint the necessary personnel to dispose of the misfired charge; and determine the safe and proper method of its disposal. R 128 Operations during thunderstorm
In the event of a thunderstorm, any handling or use of explosives shall be stopped immediately; and there shall be immediate evacuation of all persons in the area where the explosives are being handled or used to a place of safety in a proper location as determined by the designated person.
Risk control
Elimination / Substitution
• Use alternate methods of demolition Engineering Control
• Cordon off the area Administrative Control
• Control of open lights and smoking • Safe work procedure
• Audible warning prior to blast • Inspection by blaster for misfires. • Comply with legal requirements
Copyright © 2012 NTUC LearningHub Pte Ltd. All rights reserved 138 6.11 EXCAVATION
The hazards of excavation are • Open sides / Inadequate access • Unsupported sides / Inadequate shoring
• Presence of underground utilities / Unqualified operator • Presence of hazardous atmosphere
• Presence of ground water / Raining / Rupture of underground water pipes • Presence of adjacent structures
• Materials stored near to the edge of the excavation
• Presence of workers in the operational zone of the excavator / Unqualified operator • Vehicles / Equipment close to the edge of the excavation
The potential accident would be • Falling into the excavation • Collapse of excavation • Damage to utilities • Collapse of person • Flooding • Collapse of structures • Falling objects • Struck by excavator • Vehicles / Equipment topple Legislation
WSH (Construction) Regulations
R 77 General requirements on excavation work
Where the depth of any excavation in a worksite exceeds 1.5 metres or where the banks are undercut, adequate shoring (by underpinning, sheet piling, bracing or other means of shoring) shall be provided to prevent collapse of the excavation, or any structures adjoining or over areas to be excavated. No shoring shall be required if the excavation in the worksite has been examined and certified by a professional engineer to be safe without any shoring.
Where the depth of any excavation in a worksite exceeds 4 metres, adequate shoring shall be made or erected in accordance with the design of a professional engineer to prevent collapse of the excavation, or any structures adjoining or over areas to be excavated. Where the depth of any excavation in a worksite exceeds 4 metres, no work (other than excavation or shoring operations) shall be carried out inside the excavation until after a certificate has been issued in respect of the shoring for that excavation.
During any excavation work in a worksite, all reasonably practicable measures shall be taken
• to prevent any person being trapped by the collapse of the excavation;
• to prevent any person being struck by an object, such as an excavating machine or by any material dislodged by the machine;
• to prevent any person falling into the excavation; and
• to prevent any person inhaling, or otherwise being exposed to, carbon monoxide or another impurity of the air in the excavation.
Excavated material or other superimposed loads shall be so placed away from the edge of the excavation in a worksite to prevent the materials or other loads from falling into the excavation, or cause the banks to slip or cause the upheaval of the excavation bed. The open side of any excavation in a worksite which exceeds 2 metres in depth shall be provided with adequate guard-rails to prevent persons from falling into the excavation.
Copyright © 2012 NTUC LearningHub Pte Ltd. All rights reserved 139 Notices shall be put up at appropriate and conspicuous positions to warn persons about the excavation in a worksite.
The excavation in a worksite and its vicinity shall be inspected by a designated person after every rain storm or other hazard-increasing occurrence. Where any inspection reveals that the excavation in the worksite is not safe for entry, the designated person shall immediately inform the project manager of the worksite of the unsafe condition. Upon being informed, the project manager of the worksite may order that all works within the excavation cease immediately and revoke any permit-to-work issued for such work. It shall be the duty of the designated person to take, so far as is reasonably practicable, such measures as are necessary to ensure that any inspection carried out is conducted properly.
R 78 Duties of professional engineers on excavation
The professional engineer who designs the shoring for an excavation shall ensure that his design can be executed safely and provide all design documentations. The professional engineer who oversee the construction of the shoring shall ensure that the shoring is constructed in accordance with the design and issue a certificate stating that the shoring is safe for its intended use.
R 79 Access and egress from excavation
where any excavation work is carried out to ensure that safe access to and egress from the excavation in the worksite is provided where persons are required to work in the excavation; and the access or egress is sufficient in numbers and installed in such locations so as to be readily accessible.
Risk Control Engineering Control
• Provide shoring for the excavation • Provide shoring for adjacent structures • Provide barricades
• Cordon off the operational area to prevent entry by unauthorised personnel. • Provide staircase for access
• Provide stoppers for vehicles / equipment. • Provision of water pumps.
Administrative Control
• Engage a Licensed Cable Detection Worker (LCDW) to check for the presence of underground electricity cables, telecommunication cables, water mains, sewers and gas pipes
• Obtain relevant services layout plans
• Dig trial holes manually to ascertain the layout
• Apply permit to work for excavation/trench that exceeds 1.5m depth. • Place materials away from the edge of the excavation.
• Inspection by designated person
• Provision of banksman to direct the operation and control access. • Provide signage to warn pedestrians and vehicles.
• Walkie talkie for banksman
• Brief personnel on the location of services • Provide ground markers above the services. • Gas testing for hazardous atmospheres. Personal Protective Equipment
• Safety helmet for all personnel • High visibility vest for banksman
Copyright © 2012 NTUC LearningHub Pte Ltd. All rights reserved 140 6.11.1 TUNNELLING HAZARDS
The hazards of tunnelling are: • Inadequate access • Inadequate shoring
• Presence of underground utilities • Presence of hazardous atmosphere
• Presence of ground water / Raining / Rupture of underground water pipes • Presence of adjacent structures
• Presence of workers in the operational zone of the tunnel equipment The potential accident would be
• Falling into the shaft • Collapse of tunnel • Damage to utilities • Collapse of person • Flooding
• Collapse of structures • Struck by tunnel equipment Legislation
WSH (Construction) Regulations R 81 Stability of tunnelling work