The Hierarchy of Controls is a systemised approach to identifying and implementing chemical hazard controls. This blog discusses engineering controls and how they fit into the overall hazard control hierarchy (we’ll also look at what can cause them to fail). Like all hazard control measures, engineering controls should be selected after careful analysis of the workplace, the job tasks being undertaken, as well as the physical and health hazards presented by the chemicals.
What is an engineering control?
An engineering control is a piece of equipment, a machine, or mechanical device designed to minimise the harm associated with a chemical hazard. Engineering controls can reduce harm by:
Isolating workers from chemicals (eg, using a self-contained lube station)
Enclosing high risk operations in sealed areas (eg, sealing off an area that is only opened during maintenance and cleaning)
Extracting contaminants from the breathing zone of workers (eg, installing a Local Exhaust Ventilation (LEV) system)
Automating tasks so workers no longer need to perform them (eg, using robots to spray paint new cars)
Segregating incompatible chemicals from one another (eg, installing compliant safety cabinets and chemical stores).
Engineering controls can change the physical layout of a work area (eg, using a LEV when cutting timber) or even the entire workplace (eg, relocating chemical stores to isolate Dangerous Goods). It is essential to consult the workers and contractors who work in those areas as some engineering controls (machinery, equipment, contained environments) will require changes to operating procedures and housekeeping practices. If you’re staff aren’t part of the process they might resist embracing the new technologies and place themselves at further risk.
IMPORTANT: Even if an engineering control completely isolates (or removes) workers from a task, you will probably still need to implement administrative controls (training, supervision, operating procedures) and PPE.
How do engineering controls fit into the ‘Hierarchy of Controls’?
The Hierarchy of Controls is a recommended method for selecting hazard control measures by grouping different types, then ranking them in order of effectiveness. There are 5 different groups ranked in the following order:
Elimination Controls - any control measure that results in the chemical hazard being completely eliminated.
Substitution Controls - control measures that look for safer ways of carrying out the same task, or using less harmful chemicals.
Engineering Controls - control measures that are physical in nature and focus on machinery, tools, equipment, and workplace design to reduce chemical exposure.
Administrative Controls - control measures that are carried out by management, workers and contractors through safe work methods, operating procedures, housekeeping, and hygiene practices.
Personal Protective Equipment (PPE) Controls - any control measure that requires a worker to wear or use PPE.
To use the Hierarchy of Control, for each chemical hazard work your way through the 5 different types of control measures and look for different ways to minimise the effect of the hazard. Always try to eliminate the hazard completely if you can (that’s why Elimination Controls are ranked #1) and then implement other measures giving priority to control measures with the highest rankings.
The Hierarchy of Control recognises that for many chemical hazards, more than control measure is required. This is especially true for engineering controls which rely heavily on correct operating procedures, preventative maintenance, and cleaning. You should always be looking at the way control measures support (or negate) each other.
What causes an engineering control to fail?
Engineering controls can fail for a number of reasons, but usually the cause is traced back to a human factor, either direct or indirect. Let’s look at all three below:
1. Inappropriate risk assessment
Many engineering control measures fail because a thorough risk assessment was not conducted in the initial stages. Workplaces purchasing expensive equipment and machinery based on industry ‘best-practices’ alone, and without considering the unique setup and operations of their own workplace run the risk of equipment that just doesn’t work or introduces new hazards. Here’s a few examples:
Local Exhaust Ventilation (LEV) system that is always choking because it doesn’t have the capacity for the amount of wood dust produced everyday.
Relocating a flammable liquids store to an outdoor area but the new location sits within the turning circle of forklifts and supplier delivery trucks.
2. Technical problems
An engineering control can fail if the equipment or device has not been installed correctly or has mechanical faults. Again you need to ensure that your risk assessment completely evaluates the installation phase as well as any ongoing maintenance program.
3. Human factors
Human factors are the main reason engineering controls fail. Operators use equipment incorrectly or not at all — and many times the problem begins when management have not consulted the workers and contractors who use (or are effected by) the engineered devices and machinery.
Workers (understandably) become upset when their workplace changes and they don’t understand why. When workers are involved in the risk assessment process they have a greater understanding about how a piece of machinery or a change to the layout of their work bench is improving their personal safety. Consulting your staff will help you understand the most practical methods and help you to avoid engineering controls that are misused or avoided by your staff. Here’s a few examples:
Machinery shields that restrict movement and vision (staff don’t feel comfortable using them)
LEV systems that require frequent repositioning (staff don’t want to waste time setting them up)
Dust collectors that choke and shutdown machinery (workers aren’t clearing them regularly)
Chemical stores that were originally installed correctly but now contain substances from different hazard classes, and chemicals in open containers (management aren’t enforcing strict housekeeping and hygiene procedures)
But engineering controls can also fail when workers and contractors have not received proper training and don’t know how to use, clean, and maintain the machinery and plant that has been implemented for their safety. Training must also be supported with proper supervision and remedial actions if workers are observed to be not following safety protocols.
Are you ready to conduct a full risk assessment on the chemical hazards at your workplace and evaluate the existing engineering controls you have in place? Download our free eBook How to manage the risk of Hazardous Chemicals in the workplace for full instructions as well as practical templates and tools to get you started. Download and read it today by clicking on the image below: