bizSAFE Certification Singapore Hierarchy of Risk Control Questions and Answers — Questions and Answers
Question 1: A metal fabrication workshop in Tuas has a cutting machine that generates noise levels exceeding the 85 dB(A) permissible exposure limit set by Singapore's WSH (Noise) Regulations. According to the Hierarchy of Risk Control, what is the most effective measure the company should consider first?
- Issuing all affected workers with approved earplugs.
- Implementing a job rotation schedule to limit each worker's exposure time.
- Replacing the noisy machine with a modern, quieter laser cutting system. (Correct answer)
- Installing acoustic enclosures around the existing machine.
Correct answer: Replacing the noisy machine with a modern, quieter laser cutting system.
The Hierarchy of Risk Control prioritises measures that are most effective. Elimination and Substitution are at the top. Replacing the noisy machine with a quieter one (Substitution) is more effective because it removes the hazard at the source. Engineering controls (enclosures), Administrative controls (job rotation), and PPE (earplugs) are lower down the hierarchy.
Question 2: In the context of the WSH (Risk Management) Regulations, which of the following is the best example of an 'Engineering Control'?
- Conducting a daily toolbox meeting before starting work.
- Installing a fixed guard on the rotating blade of a saw. (Correct answer)
- Requiring workers to wear safety boots on site.
- Using a water-based paint instead of a solvent-based one.
Correct answer: Installing a fixed guard on the rotating blade of a saw.
Engineering controls are physical modifications to a process or equipment to isolate people from the hazard. Installing a fixed guard is a physical barrier engineered to prevent contact. A toolbox meeting is an administrative control, safety boots are PPE, and using a different paint is substitution.
Question 3: A company is developing Safe Work Procedures (SWPs) for handling chemicals in its Jurong Island facility. The implementation of these SWPs falls under which level of the Hierarchy of Risk Control?
- Engineering Controls
- Substitution
- Personal Protective Equipment (PPE)
- Administrative Controls (Correct answer)
Correct answer: Administrative Controls
Administrative controls are work practices or procedures that change the way people work to reduce exposure to a hazard. Safe Work Procedures (SWPs), training, and warning signs are all classic examples of administrative controls.
Question 4: A contractor is tasked with cleaning the facade of a high-rise building in the CBD. Several control measures are proposed. According to the principles promoted by Singapore's WSH Council, which of the following is considered the LEAST effective control measure?
- Using a water-fed pole system that allows cleaning from the ground.
- Requiring workers to use a full-body harness and lanyard (fall arrest system). (Correct answer)
- Using a Building Maintenance Unit (gondola) with rigid guardrails.
- Scheduling the work to be done only during daylight hours and in good weather.
Correct answer: Requiring workers to use a full-body harness and lanyard (fall arrest system).
Personal Protective Equipment (PPE), such as a fall arrest system, is the last line of defence in the Hierarchy of Controls. It does not remove the hazard (working at height) but only minimises the consequences of a fall. Elimination (cleaning from the ground), Engineering Controls (gondola), and Administrative Controls (scheduling) are all preferred over PPE.
Question 5: What is the fundamental principle behind the structure of the Hierarchy of Risk Control as emphasised in Singapore's Risk Management Code of Practice (RMCP)?
- To ensure that the cheapest control measures are implemented first to manage costs.
- To prioritise controls that are most reliable and place the least reliance on human behaviour. (Correct answer)
- To focus on controls that are easiest and quickest to implement for all identified hazards.
- To ensure that Personal Protective Equipment (PPE) is the primary control for all high-risk tasks.
Correct answer: To prioritise controls that are most reliable and place the least reliance on human behaviour.
The hierarchy is structured from most to least effective. The most effective controls (Elimination, Substitution, Engineering) are designed into the process and are more reliable because they do not depend on workers following rules or using equipment correctly. Lower-level controls like administrative procedures and PPE are highly dependent on human behaviour and thus less reliable.
Question 6: Under the WSH (Risk Management) Regulations, when a company identifies a risk, it must implement control measures. What does the mandated use of the Hierarchy of Controls imply?
- The company must implement at least one control from each of the five levels for every high-risk task.
- The company must justify why higher-level controls like Elimination or Substitution are not 'reasonably practicable' before settling for lower-level controls like PPE. (Correct answer)
- The company can choose any control measure as long as it lowers the risk level and is documented in the Risk Assessment.
- The company is only legally required to implement Administrative Controls and PPE.
Correct answer: The company must justify why higher-level controls like Elimination or Substitution are not 'reasonably practicable' before settling for lower-level controls like PPE.
The WSH (Risk Management) Regulations and the Code of Practice require employers to apply the hierarchy sequentially. This means they must aim for the highest, most effective level of control first. If they choose a lower-level control, they must be able to demonstrate and justify why the more effective options were not reasonably practicable to implement.
