In the last article we discussed ergonomic assessments. If you find that workplace tasks involve physical activities that increase the risk for Musculoskeletal Disorders (MSDs), it would be beneficial to reduce those risks. This is especially important when those risks take place during a majority of the work shifts. Frequency and repetition of an action lead to greater risk of MSDs.
Activities that increase the risks of MSDs:
• Frequent manual material handling
• Exposure to extreme temperatures
• Exposure to excessive vibrations
• Repetitive motions throughout the work shift
• Awkward or stationary work positions
• Utilization of excessive force or localized pressure to perform tasks
• Unnecessary lifting of heavy and awkward items
• Improperly padded or adjusted seating
• Pounding
• Twisting
• Squatting
• Bending
• Improper skeletal alignment
• Eye strain
• Stretching
• Standing long periods or on hard surfaces
Reducing these hazards or risks can be completed through administrative controls, engineering controls and the use of personal protective equipment.
The National Institute for Occupational Safety and Health (NIOSH), and the Occupational Safety and Health Administration (OSHA), provides the following recommendations:
Engineering Controls:
Rearranging, modifying, redesigning, providing or replacing tools, equipment, workstations, packaging, parts, processes, products, or materials.
Administrative Controls:
• Alternate heavy tasks with light tasks.
• Provide variety in jobs to eliminate or reduce repetition.
• Adjust work schedules, work pace, or work practices.
• Provide recovery time.
• Modify work practices so that workers perform work within their power zone.
• Rotate workers through jobs that use different muscles, body parts, or postures.
Always remember the following when arranging workstations:
• The straighter, the more erect, the worker’s body is maintained, the less weight and stress is placed on the worker’s body.
• The lifting zone of the worker’s body is between the shoulders, and their knees. (See figure 1)
• Eliminate or reduce as much reaching as possible, especially any that requires the worker to bend while reaching.
• The area of the least stress for the body to keep when manipulating and lifting is between the shoulders and the waist.
• Eliminate or reduce lifting that requires the worker’s spine to be in positions other than straight.
• Use lifting aids or equipment whenever possible.
• Eliminate or reduce tasks that require impact.
• The harder the standing surface, the more impact, and stress is placed on the worker’s body.
We will take each activity listed above, and suggest ways to reduce the hazards or MSD’s risks.
Frequent manual material handling
This risk is very common in the pallet industry as it is in most all wood products and production industries. Modern mechanical material handling systems have reduced a lot of the frequency, but it’s difficult or impossible to eliminate it all. Arranging workstations, tables, conveyors, and other material handling equipment so that all material handling is done between the worker’s chest and waist. Reduce any physical activity that includes twisting, reaching and bending as much as possible. Install mats at locations where workers stand. Encourage workers to wear shoes with good support and cushioned soles.
Exposure to extreme temperatures
Colder temperatures create more stress on the worker’s body and will increase frequency of injuries from material handling and manipulating. Provide heat, head and hand protection, and encourage layering.
Exposure to excessive vibrations
Eliminate or reduce vibration where possible. Provide hand protection for vibrating power tools, and padding where the worker comes in contact with vibration.
Repetitive motions throughout the work shift
Rotate shift job tasks, and or personnel to reduce prolonged exposures. Provide ample recovery and or break periods. Engineer material handling equipment to eliminate or reduce the requirement for repetitive motion.
Awkward or stationary work positions
Engineer workstations to eliminate or reduce awkward positioning. Provide adjustable chairs where applicable that provide back support, arm rests, and allow the worker’s feet to be placed flat on the floor, or have a support/rest platform for the worker’s feet.
Keep in mind that not all ergonomic chairs will fit every worker. Organize workstations so that workers sit or stand erect and maintain a good posture while working. Prolonged sitting and poor body posture applies stress on the lower back, and lack of physical activity may lead to other health risks. Organize tasks so that the need for reaching is reduced.
Utilization of excessive force or localized pressure to perform tasks
Eliminate or reduce tasks that require excessive force or localized pressure. Provide padding, insulated tools, hand protection, and or protection at the point of pressure.
Unnecessary lifting of heavy and awkward items
Eliminate any unnecessary lifting and manipulation of awkward items. Utilize lifting aids, provide lifting safety training, and organize workstations and job tasks to reduce twisting, bending, reaching and lifting. Promote team work when lifting.
Improperly padded or adjusted seating
Replace seating with padded chairs that have adjustable back support, adjustable arm support, foot support, and adjustable seats. Workers must have chairs that fit them, and ensure proper support and posture.
Pounding
Eliminate or reduce tasks that require pounding. Pounding applies undue force on muscles, tendons, ligaments, bones and joints. With excessive force, the muscles are contracting much harder than normal, this can lead to stress on the muscles, tendons and joints.
Twisting, Squatting, Stretching, Bending, and Improper skeletal alignment
These tasks were grouped together, since they all have similar controls in reduction of the hazards/risks. Keeping the worker’s body straight or erect while working is one of the biggest factors in reducing risks for MSDs. (See figure 2) The farther you reach the more weight and stress that you place on your body. Organizing workstations so that those items accessed frequently are closer to the worker, and those used less frequently are farther away. At the same time, reaching for an object that weighs 5 lbs. can increase the weight stress to your body by 10 times, and when reaching, twisting, and bending at your back while lifting, it can increase the weight stress on your lower back by over 400 times, in some calculations. Back belts are not recommended, since government tests are inconclusive. Sometimes the use of back belts leads workers to lift stresses that they should avoid, and this can cause injury. Tests are inconclusive on back belts and injury prevention for routine workplace situations. Therefore, OSHA does not recommend the use of back belts.
In figure 3, the illustration shows three zones; green, orange and red zones. The green zone is the safety area, and distance for your body to work and lift. As you reach away from your body, you increase the stress and weight of the load on your body, thus increasing the risk for injury.
The orange zone increases your risk for injury, and the red zone illustrates a very high risk of injury when reaching and lifting at that distance from your body. When you lift an object standing erect, you want to keep the object close to your body, and at a height no greater than your chest, and at a lower level no lower than your waist. This applies the least amount of stress and weight on your body and lower back. When lifting a load, and twisting or bending at the same time, you increase the weight, and stress on your body and back while under load. This is a very common cause of lower back injuries as well as arm and shoulder injuries. It takes as little or less, than a pound of weight, to stress and load your lower back to the point of serious injury, when bending your back at full extension or reach. This is why safe lifting always includes proper training. You need to remind employees to keep their back straight and bend at their knees and not with their back.
Eye strain
Eye strain can be caused by many factors, such as working in poor or low lighting, or in areas of intense light or glare. Headaches, eye pain and even permanent eye disorders can be created from eye strain. Position workstations to reduce outdoor glare. Also installing lighting at workstations can reduce glare and eye strain. New innovations in lighting have made great improvements in eye strain. New lighting, such as LED, can create a more even lighting, and be much cheaper to use. Even or equal lighting throughout the workplace reduces glare, and eye strain. There have been some government incentive programs available for changing to LED lighting. You may check with your power company for information about these incentives if available.
Standing long periods or on hard surfaces
Standing and being on your feet for an entire shift causes stress throughout your body. This can include back pain, pain in your legs, knees and feet, as well as stress that can cause neck pain and even headaches. Floor padding and workstation mats will make a big difference in the risk factors from standing long periods and working on hard surfaces. This is especially true when working on cold floors. Encourage the use of shoes with good arch support and padded soles. Rotate workers from standing positions to seated positions, or make seating available for workers if desired.
Once you have completed an ergonomics assessment, made administrative control changes, engineering control changes, and provided the necessary personal protective equipment, you still need to ensure your workers are provided with the proper initial training and annual refresher training. Job tasks and workstations should be re-evaluated periodically, and especially in the event of a workplace injury or illness.
Editor’s Note: Jary Winstead is a safety consultant, author and trainer who serves a variety of industries including the forest products sector. He owns Work Safety Services LLC and can be reached at safejary@gmail.com.
