Controlling Ergonomic Hazards
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Ergonomic improvements are changes made to improve the "fit" between a job and the capabilities of the employees performing it. Making ergonomic improvements reduce physical demands, eliminate unnecessary movements, lower injury rates and their associated workers' compensation costs, and reduce employee turnover. When making improvements to ergonomics problems, we use the "Hierarchy of Controls" (HOC) described within the ANSI/ASSP Z10-2012, Occupational Health and Safety Management Systems..
The first three strategies focus on doing something with the hazard.
- Elimination: The best solution is to totally eliminate the need to lift, lower, push, pull, or carry heavy loads. For instance a hand truck could be used to move heavy boxes in a warehouse, eliminating the need carry them.
- 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 a challenge because supervisors must regularly monitor their employees as they perform tasks. Bottom line, these controls work only so long as employees "behave" properly.
- Personal Protective Equipment (PPE): The use of PPE is probably the most common strategy use for all hazards. PPE forms a barrier between workers and hazards. For instance, knee pads might be used to protect the knees when laying carpet.
Good engineering can reduce the stress of lifting heavy objects.
The most effective way to control ergonomic hazards is to eliminate the risk factors altogether through elimination or substitution. When those options are not suitable,
sometimes you can change the tools, equipment, job design, or work area to mitigate the hazard.
Engineering improvements include rearranging, modifying, redesigning, or replacing tools, equipment, workstations, packaging, parts, or products. These improvements can be very
effective because they may eliminate or reduce the hazard through barriers, isolation, enclosure and other methods.
Here are some examples of how engineering controls can be used to reduce ergonomic injuries:
- Use a device to lift and reposition heavy objects to limit force exertion.
- Reduce the weight of a load to limit force exertion.
- Reposition a work table to eliminate a long/excessive reach and enable working in neutral postures.
- Use diverging conveyors off a main line so tasks are less repetitive.
- Install diverters on conveyors to direct materials toward the worker to eliminate excessive leaning or reaching.
- Redesign tools to enable neutral postures.
Engineering Control Improvement Options
Nine tips for workstation design.
- Raise or lower the work surface or the employee. This reduces bending, reaching, and awkward postures. A rule of thumb is to try to keep your hands at about elbow height when
- Use cut-out work surfaces to get closer to the work. This reduces visual effort and awkward postures.
- Reposition the work to reduce bending and reaching.
- Reconfigure the workstation so that sliding and rolling replaces lifting and carrying.
- Use adjustable equipment that allows for a comfortable, upright working posture.
- Provide close, convenient storage for frequently used materials, parts, or tools to reduce reaching and awkward postures.
- Provide comfort: Foot rests, padding, and good lighting, all make work more comfortable.
- Use lifting aids to reduce force, repetition, and awkward postures in lifting or handling tasks. Examples of assist devices include vacuum lifts, manipulators, mechanical
lifts, workstation cranes, scissor lifts, and automatic feed systems.
- Use mechanical aids to 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
Ergonomically designed tools.
Good design and proper maintenance can help reduce pressure points on the hands, awkward postures (e.g., bent wrists), forceful exertions, and other contributing factors.
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. When selecting and purchasing
hand tools, the guidelines listed below should be followed.
- Select tools that allow the wrist to be held straight and that minimize twisting of the arm and wrist. Good working posture can be maintained when properly designed tools are
- 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, palm of the hand).
- For power or pneumatic tools, select tools with vibration dampening built in whenever possible. Provide personal protective equipment such as gel-padded gloves to reduce exposure
- Use better, ergonomically-designed tools which may be lighter weight, require less force to operate, fit the hand better, and are more comfortable to use.
Tools and Equipment Selection (continued)
The handles allow a power grip.
Consider the following when choosing tools:
- Handles that are rounded, soft and padded, and do not have sharp edges or deep grooves reduce pressure points on fingers and hands.
- Handles should be at least 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.
Triggerless tools 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 can help by reducing forceful exertions by supporting the weight of the tool.
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
Reasonable schedules, job rotations, and training are all administrative controls.
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 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 particular job.
- Adjust work schedules, work pace, or work practices. Limit the amount of time any employee has to spend performing a "problem job." Job hardening suggests new workers who are not
used to the physical demands of the job should be gradually introduced to a normal work pace.
- Provide recovery time - recovery periods (i.e., muscle relaxation periods) can help prevent fatigue and injury to muscles.
- 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.
Administrative Controls (continued)
Stretching exercises can help for prolonged periods of time.
Regular housekeeping to eliminate clutter can reduce reaching, bending, or twisting when handling materials, tools, or objects. Keep floor surfaces dry and free of obstructions
to help eliminate slipping and tripping hazards.
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 amount of force and repetition required when using the tools.
Exercise and Stretching
Long-term, sensible exercise and stretching have many benefits, which may include better health and reduced injuries. New, returning, or injured employees should gradually
increase their physical activity.
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
Back Safety - Top 10 Lifting Rules
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 force, 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 objects you lift are close to the body and at waist height.
- Don't lift awkward objects such as long pipes or large boxes by yourself. Get help or use mechanical assists.
- 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.
The images below illustrate safe lifting techniques.
A program to teach workers how to lift properly should be used in combination 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
Back belts remind you to use safe lifting, but that's it.
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 anti-fatigue soles can prevent employees from slipping and prevent fatigue from long hours of standing on hard surfaces.
- Knee and elbow pads can 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 are not to be used as personal fall arrest system (PFAS), in some instances they may be used for
Back belts may help maintain the proper curvature of the spine during lifting or physical exertion and may also provide comfort and confidence while performing work tasks. However,
you can't lift heavier loads just because you're wearing a back belt. If you use them all-day-every-day, your back muscles may actually get weaker.
Prioritize Your Work
Conduct ergonomic JHAs to prioritize jobs.
You may want to choose some specific improvement options to try in your workplace. Setting your priorities will help you sort out which tasks you want to work on first. To do
that, conduct ergonomics job hazard analyses (JHA) of hazardous tasks. JHAs focus on:
- worker variables (fitness, age)
- types of work (e.g., plant, warehouse, office, driving, etc.), 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 task
- ideas your employees have for improvements
- 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
For more information on general ergonomic factors in the workplace, please see OSHAcademy courses 711 Introduction to
Ergonomics, 722 Ergonomics Program Management, and 706
Conducting a Job Hazard Analysis (JHA).
Check your Work
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If you have time, watch This Montana State Fund video that covers ergonomic basics that apply to virtually any workplace.