The Hierarchy of Control is a method for deciding on effective risk control measures to implement at a workplace. It is also a key requirement of the Code of Practice: Managing risks of hazardous chemicals in the workplace published by Safe Work Australia. This blog walks you through six different approaches to hazard control measures and how these are individually ranked within the hierarchy. We also demonstrate how the Hierarchy of Control fits into a compliant risk management methodology.
Identifying and assessing chemical hazards
Before you even begin thinking about implementing chemical risk control measures, you need to identify each of the substances kept at the worksite and assess how they could cause harm to your workers (or damage buildings, property, environment). Identifying chemical hazards and assessing their level of risk are the first two steps in a four step risk management methodology. The four steps are listed below:
STEP 2: ASSESS each of the chemical hazards and the severity of any dangerous events, injuries, or illnesses they could cause. You’ll finish this step with a prioritised action plan based on how likely each event could actually happen.
STEP 3: CONTROL use the Hierarchy of Control to determining the most effective ways to eliminate or minimise the risk. Then implement the controls.
STEP 4: SUSTAIN compliance by implementing systematic reviews, safety auditing and scheduled maintenance.
IMPORTANT: Working through a risk management methodology ensures that each chemical hazard is correctly identified and the level of danger fully assessed. The Hierarchy of Control is an essential step in the methodology and should not be used on its own.
Hierarchy of Control for chemical hazards
The Hierarchy of Control is a way of ranking risk control measures — from the most reliable and effective level of protection — to the least. When controlling chemical hazards, eliminating the chemical completely is always the most desirable approach (if possible), but if this is not practicable you should assess other control methods in the following order:
Elimination — stop using a hazardous chemical and completely eliminate that work process.
Substitution — use another less harmful chemical or substance.
Isolation — separating the chemicals from workers.
Engineering — use mechanical devices or processes to minimise exposure to the chemicals.
Administration — implement safe work methods and operating procedures.
Personal Protective Equipment — have staff wear PPE while using the chemical.
When identifying and assessing control measures you should consider all six ranks in the Hierarchy of Control because if the chemical hazard cannot be eliminated, you may need to implement more than one control measure.
IMPORTANT: Administrative controls and PPE are the least effective as they rely on human behaviour. People forget, make mistakes, or are sometimes just too slack to follow instructions. If possible these control measures should accompany and reinforce other controls.
HAZCHEM Controls: workplace example
A manufacturing plant uses a highly toxic and corrosive chemical in their manufacturing processes. The chemicals are located in large vats with lids over the top in an open work area, accessible to all workers and contractors. Last month a worker stood on one of the lids while doing some repairs, the lid collapsed and the worker fell in and died. Using the Hierarchy of Control let’s consider the effectiveness (and practicalities of possible control measures).
PLEASE NOTE: This is a hypothetical example (though a worker in the USA really did fall into a vat of corrosive chemicals after the lid broke — he died). The purpose of the example is to demonstrate how to approach the HOC rather than offer practical control methods.
Elimination — the best method would be to stop using the hazardous chemical completely. In simpler examples sometimes this can be achieved by outsourcing or following a different line of business. But if your enterprise requires a specific chemical for manufacturing your core products, elimination will not be impossible (unless you shutdown your operations). This hazard is a combination of the presence of a chemical and workers standing on top of the vat, so you should also look at ways of eliminating the need to stand on the vat.
Substitution — the next level of protection is to consider alternative chemicals or materials that could be used in the manufacturing process. When substituting chemicals you need to consider if the new substance could introduce additional hazards to the job site. Maybe the new chemical is less toxic but it is more reactive to heat or has a pungent smell.
Isolation — is there anyway you could isolate the chemical away from workers? Could you place the chemical vats in rooms operated remotely by robots or mechanical devices? Perhaps you could restrict access to the manufacturing floor and reduce the amount of personnel exposed to the chemicals. A chemical hazard would still exist but there now might only be 5 workers exposed to the chemical vats instead of 75.
Engineering — what mechanical devices or machinery could you use to minimise exposure to the chemicals? Could you devise a way to fully contain the chemicals in the vats then drain the individual vats before maintenance is carried out. Could you manufacture another platform over the lids so a worker is never standing directly on the vat? Similar to ‘substitution’ control measures, you’ll also need to assess if new hazards have been introduced by the mechanical devices — could someone accidentally open the lid to a vat that had not yet been emptied?
Administration — administrative controls like safe work methods and operating procedures support other control measures and should never be used in isolation. For example: creating an operational procedures that restricts access to the chemical vats may not work without also installing require physical barriers (keypad locked doors, gates) to keep unauthorised people out.
Personal Protective Equipment — even if you had staff wearing full protection suits, workers could still fall into that vat of chemicals. PPE is vulnerable if it doesn’t fit; gets lost, forgotten, stolen; or if it is damaged or torn while being worn. PPE must never be used as a single control measure.
IMPORTANT: Once you decide on your control measures and implement them the operations of your workplace, make sure you conduct another risk assessment to ensure the effectiveness of the control measure.
This blog has introduced you to the Hierarchy of Control and given you an understanding of how control measures are ranked in order of reliability and protection. Now we suggest downloading our free eBook How to manage the risk of Hazardous Chemicals in the workplace to learn how to include these hazard control measures into your site’s risk management plan. Download and read it today to get your workplace fully compliant with Australian WHS legislation and Safety Standards.