Issues with wall chasing
WorkSafe is seeing ongoing non-compliance with wall chasing work, such as:
- Use of petrol powered saws without local exhaust ventilation (LEV) on-tool, exposing workers to toxic carbon monoxide;
- Cutting above shoulder height, against the saw manufacturer’s instructions for use – kick-back could cause serious or fatal injuries;
- Inadequate dust control which may give rise to respirable crystalline silica (RCS) exposure; and
- Slurry from wet cutting left on site – risk of slip injuries, risk of silica dust exposure when dry.
Carbon monoxide risk
Air monitoring tests carried out by WorkSafe show that carbon monoxide exposures from petrol powered saws are well above the legal exposure standard regardless of whether the roof has been installed. Carbon monoxide exposure can cause:
- Weakness, tiredness, nausea, headache, collapse; and
- Permanent damage to the heart muscle, increasing the risk of earlier death.
Control chasing risks
Designers of buildings for commercial clients must provide a written report which identifies the hazards to which a person at the construction site is likely to be exposed, the designer’s assessment of those risks and what things the designer has done, or has not done, to reduce those risks.
Main contractors should have a policy on safe chasing and should ensure that the contractors they employ follow this policy. Site supervisors should attend site during chasing work at times, to check that safe equipment and procedures are being used.
Employers of workers undertaking chasing work should implement practicable controls including:
- Choosing equipment that is suitable for wall chasing, and following the manufacturer’s instructions on how to use the equipment;
- Only using petrol powered saws indoors (roof on or off) if local exhaust ventilation is installed on the exhaust and water is used for dust suppression. Note - Pedestal or general purpose fans or personal protective equipment are insufficient to reduce the risks of carbon monoxide exposure from petrol powered saws.
- Consider selecting a compliant wet electric saw that is protected by a residual current device (RCD), an electric saw with on-tool dust extraction, or a pneumatic or hydraulic system. Check the manufacturer’s instructions for suitability for wall chasing. For example, a grinder with vacuum extraction (“grinder-vac”) may be used, in conjunction with a respirator;
- Using appropriate work platforms to eliminate the need to work in a position where the elbows are raised above the height of the shoulders;
- Leaving the site in a clean state at the end of the task, including removal of slurry;
- Provide appropriate personal protective equipment; and
- Document the risks and controls in your Safe Work Method Statement and ensure workers have been informed of all hazards and trained in safe work methods.
Health surveillance must be provided if workers have been exposed to dust containing RCS during chasing work activities.
Workers should ensure they follow the employer’s directions in relation to using safe equipment and safe work methods.
WorkSafe - Safety alert 09/2009 - Masonry cutting grinder causes death
Code of practice - Concrete and masonry cutting and drilling
Guidance note - Prevention of carbon monoxide poisoning from petrol and gas powered equipment
WorkSafe - Silica hazards
WorkSafe Media Release 2016 - Wall chasing work needs adequate controls
Health surveillance - Silica
Frequently asked questions - Silica