If you’re like most business owners, you’re always looking for ways to improve productivity and efficiency in your workplace. One way to do this is by implementing ergonomics controls into your workstation setup. But with so many different options available, it can be difficult to know where to start. In this blog post, we will discuss the hierarchy of ergonomics controls and explain what each one does.
Hierarchy of Ergonomics Controls
There are different ways to control ergonomic risks in the workplace. Some methods are more effective than others, and some are more applicable to certain types of workplaces than others. The most effective way to control ergonomics risks is through a hierarchy of controls.
Ergonomic improvements are changes made to improve the “fit” between a job and the capabilities of the employees performing it. Making ergonomic improvements reduces physical demands, eliminates unnecessary movements, lowers injury rates and associated workers’ compensation costs, and reduces employee turnover. When improving ergonomic problems, we use one or more strategies in the “Hierarchy of Controls” (HOC). We encourage employers to use the HOC described in the ANSI/ASSP Z10, Occupational Health, and Safety Management Systems.
The first three strategies focus on doing something with the hazard.
- Elimination: The best solution is eliminating the need to lift, lower, push, pull, or carry heavy loads. It may also be impossible to complete projects without placing workers in unusual postures, overreaching, or overexertion.
- Substitution: Substitution is the next-best solution. For instance, the employer might replace large, heavy containers with smaller containers.
- Engineering Controls: Redesign or modify equipment and processes. For instance, processes that require heavy lifting, lowering, or carrying heavy objects might be revised.
The last three strategies focus on doing something with behaviors to reduce exposure to the hazard.
- Warnings: Warnings may be visual, audible, or both. They may also be tactile. Visual warnings include signs, labels, tags, and lights. Audible warnings include alarms, bells, beepers, sirens, horns, and announcement systems. Tactile warnings may include vibration devices or air fans.
- Administrative Controls: The primary focus is to develop and incorporate safer behaviors and work practices through written safety policies and rules, supervision, and training. This strategy is challenging because supervisors must regularly monitor their employees as they perform tasks. The bottom line, these controls work only so long as employees “behave” properly.
- Personal Protective Equipment (PPE): PPE is probably the most common strategy for all hazards. PPE forms a barrier between workers and hazards. For instance, knee pads might protect the knees when laying carpet.
Since the science of ergonomics involves designing the job to fit the worker, let’s look at engineering controls that improve the design of tools, equipment, and the work area to mitigate hazards.
Engineering improvements include rearranging, modifying, redesigning, or replacing tools, equipment, workstations, packaging, parts, or products. These design changes can reduce or eliminate the underlying hazards that cause injuries.
Below are a few examples of how simple engineering controls can be used to reduce ergonomic injuries:
- Use a device such as a dolly, forklift, or crane to reposition heavy objects to limit force exertion.
- Reduce the weight of a load such as lumber to limit force exertion.
- Reposition a work table to eliminate a long/excessive reach and work using awkward postures.
- Use staple guns or roofing nailers instead of hammers to shingle a roof.
- Use circular saws instead of handsaws to cut lumber.
- Use augers instead of post-hole diggers or shovels to dig holes.
Engineering Control Improvement Options
Raise or lower the work surface or the employee. This reduces bending, reaching, and awkward postures. A rule of thumb is to keep your hands at about elbow height when working.
- Use cut-out work surfaces to get closer to work. This reduces visual effort and awkward postures.
- Reposition the work to reduce bending and reaching.
- Reconfigure the workstation so that sliding and rolling replace lifting and carrying.
- Use adjustable equipment that allows for a comfortable, upright working posture.
- Provide close storage for frequently used materials, parts, or tools to reduce reaching and awkward postures.
- Provide comfort – footrests, padding, and good lighting make work more comfortable.
- Use lifting aids to reduce force, repetition, and awkward postures in lifting or handling tasks. Assistive devices include vacuum lifts, manipulators, mechanical lifts, workstation cranes, scissors lifts, and automatic feed systems.
- Using mechanical aids reduce force, repetition, and awkward postures in transporting materials and products around the workplace. Examples include adjustable carts, conveyors, and powered transport for longer distances.
Storage and Retrieval of Materials
- Provide adequate, well-lit storage with easy access to reduce repetitive reaching, bending, twisting, and forceful exertions. Use mobile, lightweight storage carts with adjustable trays. Tilted containers make access easier.
- Increase the efficient use of storage space by grouping stored items by container size or shape.
Tools and Equipment Selection
Good design and proper maintenance can help reduce hand pressure points, awkward postures (e.g., bent wrists), forceful exertions, and other contributing factors. We’ll discuss more on this topic in the next section.
Workers should not have to use their hands or bodies as a vise to hold objects; mechanical devices do this much better. Tooling fixtures and jigs should be set up to avoid awkward postures and excessive forces.
Hand tools should fit the employee’s hand; employees with small hands or who are left-handed may need tools designed specifically for these situations. The guidelines listed below should be followed when selecting and purchasing hand tools.
- Select tools that allow the wrist to be held straight and minimize twisting of the arm and wrist. Good working posture can be maintained when properly designed tools are used.
- Select tools that allow the operator to use a power grip (uses all fingers to grip), not a pinch grip (uses only thumb and forefinger). Minimal muscle force is required to hold objects in a power grip posture. The pinch grip requires excessive fingertip pressure and can lead to a cumulative trauma disorder (CTD).
- Avoid tools that put excessive pressure on any one spot of the hand (i.e., sides of fingers, the palm of the hand).
- Select tools with vibration dampening built in for power or pneumatic tools. Provide personal protective equipment such as gel-padded gloves to reduce exposure to vibration.
- Use better, ergonomically designed tools that may be lighter weight, require less force to operate, fit the hand better, and are more comfortable to use.
Handles: Consider the following when choosing tools:
- Handles that are rounded, soft, and padded, with no sharp edges or deep grooves, reduce pressure points on fingers and hands.
- Handles should be 1 to 2.5 inches in diameter to allow a “power grip” (using thumb and all fingers to grip) and 5 inches long so they do not dig into your palms.
- Handles with high-friction surfaces or moldable substances improve the grip.
- Padded handles can reduce pinch grip (using only thumb and forefinger) and pressure points on the fingers.
- Look for tools with two handles to help improve control.
Triggers: Tools without triggers use contact switches to replace the triggers. Multi-finger triggers reduce forces on any one finger. Trigger bars can be used to reduce activation forces.
Fixtures: Fixtures can help reduce forceful exertions by supporting the tool’s weight.
Ways to reduce hand-arm and whole-body vibration include:
- routine maintenance
- vibration-dampening wraps on handles
- isolating the tool from the operator
- properly fitting vibration-dampening gloves
- good design of an alternate or low-vibration tool
- suspending or supporting tools (e.g., by a fixture)
- providing vibration isolators (e.g., springs or pads) for seated work tasks
- providing cushioned floor mats for standing work tasks
- mounting equipment and work platforms on vibration-dampening pads or springs
- altering the speed or motion of tools and equipment
Administrative improvements include changing work practices or the way work is organized. They may not address the reasons for the contributing factors or other problems.
Administrative improvements usually require continual management and employee feedback to ensure that the new practices and policies are effective. Below are some best practices for the workplace:
- Alternate heavy tasks with light tasks.
- Provide variety in jobs to eliminate or reduce repetition using two primary strategies: Job rotation – rotating employees through different jobs & Job enlargement – increasing the variety by combining two or more jobs or adding tasks to a job.
- Adjust work schedules, work pace, or work practices. Limit the time an employee spends performing a “problem job.” Job hardening suggests new workers who are not used to the job’s physical demands should be gradually introduced to a normal work pace.
- Provide recovery time – recovery periods (i.e., muscle relaxation periods) can help prevent fatigue and muscle injury.
- Modify work practices so that workers perform work within their midrange or power zone (i.e., above the knees, below the shoulders, and close to the body).
- Require that heavy loads are only lifted by two people to limit force exertion.
- Establish systems, so workers are rotated away from tasks to minimize the duration of continual exertion, repetitive motions, and awkward postures. Design a job rotation system in which employees rotate between jobs that use different muscle groups.
- Staff “floaters” to provide periodic breaks between scheduled breaks.
- Properly use and maintain pneumatic and power tools.
Good Housekeeping: Regular housekeeping to eliminate clutter can reduce reaching, bending, or twisting when handling materials, tools, or objects. Keeping floor surfaces dry and free of obstructions helps eliminate slipping and tripping hazards.
Maintenance: Regular maintenance of tools and equipment can help reduce or prevent problems in work tasks. For example, keeping cutting or drilling tools sharpened and in good condition can reduce the force and repetition required when using the tools.
Exercise and stretching: Long-term, sensible exercise, and stretching have many benefits, including better health and reduced injuries. New, returning, or injured employees should gradually increase their physical activity.
Cooperation: Get help when needed to handle heavy loads. Some companies set weight limits (like 50 pounds) above which a helper is required.
Safe Lifting Techniques
Lifting can put a great strain on your back. Lifting from the floor can be particularly risky. For example, lifting a 25-pound box from the floor requires about 700 pounds of back muscle, even when you bend your knees. Below are some tips that can help protect your back when you need to lift heavy objects.
- Try out the load first. If it is too bulky or heavy, get help.
- Avoid lifts that require stretching or bending to reach the load. Redesign the work area so that the objects you lift are close to the body and at waist height.
- Don’t lift awkward objects such as long pipes or large boxes yourself. Get help or use mechanical assistance.
- When lifting, keep your back straight and lift with your legs.
- Lift slowly and carefully, and don’t jerk the load around.
- Keep the load as close to your body as possible while lifting it.
- Don’t twist or turn your spine while carrying the load.
- Make sure your path is clear while carrying the object. Remove obstacles that could cause you to trip.
A program to teach workers how to lift properly should be combined with workplace redesign that reduces the amount of lifting needed. Remember, if materials are too heavy or awkward to lift and carry safely, get help, redesign the materials to be lighter and easier to handle, or use mechanical assists such as hoists, carts, or conveyors.
Personal Protective Equipment
Safety gear, or personal protective equipment (PPE), includes gloves, knee and elbow pads, footwear, and other items that employees wear.
- Gloves can protect hands from cold or injury. However, gloves may decrease manual dexterity and make it harder to grip if they do not fit correctly. Wear good-fitting thermal gloves to help with cold conditions while maintaining the ability to grasp items easily.
- Proper footwear and antifatigue soles can prevent employees from slipping and becoming fatigued from long-standing hours on hard surfaces.
- Knee and elbow pads protect the body from pressure points when pressing against hard or sharp surfaces.
Back belts are not typically considered to be personal protective equipment. They may help maintain the proper curvature of the spine during lifting or physical exertion and provide comfort and confidence while performing work tasks. However, you can’t lift heavier loads just because you wear a back belt. If you use them all-day-every-day, your back muscles may get weaker.
Prioritize Your Work
You may want to choose some specific improvement options to try in your workplace. Setting your priorities will help you identify which tasks you want to work on first. To do that, conduct ergonomics job hazard analyses (JHA) of hazardous tasks. JHAs focus on the following:
- worker variables (fitness, age)
- types of work (e.g., roofing, sheetrock, framing), and
- the work environment (e.g., lighting, cold exposures).
To determine which tasks you want to address first, consider the following:
- frequency and severity of complaints, symptoms, and injuries
- contributing factors or other problems you have identified in a particular task
- ideas your employees have for improvements
- the difficulty of implementing various improvements
- your time frame for making improvements
- potential effects on productivity, efficiency, and product or service quality
- technical and financial resources at your disposal