Article
11 February 2007
Ergonomics is the science of designing the job to fit the worker. It gets its name from the word ergo, defined as a unit of work. Ergonomics can be defined simply as the study of work. It deals with the relationship between the worker and his working environment, or more particularly, with the limitation which human size, strength, shape and function place upon the work to be performed. Adapting tasks, work stations, tools, and equipment to fit the worker can help reduce physical stress on a worker’s body. A workers environment needs to be designed to suit his/hers capabilities, reach, height, strength, speed of movement, eyesight, and so on.
Ergonomics can be very important if the work activities and job conditions include repetitive motions throughout the workday and working in awkward or stationary positions. Using excessive force to perform tasks such as lifting, carrying, pushing or pulling heavy loads or odd shaped items can also create physical stress. Other factors that can lead to problems are exposure to excessive vibration, extreme temperatures, working more than 8 hours a day, working at a quicker pace of work and having tighter grips when using tools.
These factors and work activities can create physical stress on workers’ bodies, which can lead to injury. The problems can be increased if coupled with poor machine design, workplace design or the use of improper tools. Recognizing ergonomic risk factors in the workplace is an essential first step in correcting hazards and improving worker protection. By reducing physical stress in the workplace many of the serious injuries that take place each year can be eliminated.
Musculoskeletal Disorders
Many potentially serious and disabling work related musculoskeletal disorders (MSDs) can be eliminated from designing the job to fit the worker. Musculoskeletal disorders are injuries and disorders of the soft tissues of the muscles, tendons, ligaments, joints, nerves, blood vessels or related soft tissue including sprain, strain and inflammation, that may be caused or aggravated by work. Occupational safety and health professionals have called these disorders a variety of names, including cumulative trauma disorders, repetitive stress injuries, repeated trauma, and occupational overexertion syndrome.
MSDs can cause a number of conditions, including pain, numbness, tingling, stiff joints, muscle loss, and sometimes paralysis. These disorders include muscle strains to the neck, back, shoulders, or legs, herniated discs, tendonitis, carpal tunnel syndrome (pressure on a nerve in the wrist, resulting in numbness, tingling, pain, or weakness in the hand, wrist, or forearm). The following table presents examples of various MSD disorders, their symptoms, possible causes and diseases and typical work activities associate with them.
Examples of Musculoskeletal Disorders
Body Parts Affected |
Symptoms |
Possible Causes |
Workers Affected |
Disease Name |
thumbs |
pain at the base of the thumbs |
twisting and gripping |
butchers, hiusekeepers, packers, seam-stresses, cutters |
De Quervain's disease |
fingers |
difficulty moving finger; snapping; and jerking movements |
repeatedly using the index fingers |
meatpackers, poultry workers, carpenters, electronic assemblers |
trigger finger |
shoulders |
pain, stiffness |
working with the hands above the head |
power press operators, welders, painters, assembly line workers |
rotator cuff tendinitis |
hands, wrists |
pain, swelling |
repetitive or forceful hand and wrist motions |
core making, poultry processing, meatpacking |
tenosynovitis |
fingers, hands |
numbness, tingling; ashen skin; loss of feeling and control |
exposure to vibration |
chain saw, pneumatic hammer, and gasoline-powered tool operators |
Raynaud's syndrome (white finger) |
fingers, wrists |
tingling, numbness, severe pain; loss of strength, sensation in the thumbs, index, or middle or half of the ring fingers |
repetitive and forceful manual tasks without time to recover |
meat and poultry and garment workers, upholsterers, assemblers, VDT operators, cashiers |
carpal tunnel syndrome |
back |
low back pain, shooting pain or numbness in the upper legs |
whole body vibration |
truck and bus drivers; tractor and subway operators; warehouse workers; nurses aides; grocery cashiers; baggage handlers |
back disability |
|
Source: OSHA 3125 2000 (Revised)
Job Hazard Analysis
Job hazard analysis is a process where all activities that pose a health problem are identified. This analysis includes the identification of all jobs, operations, and work activities and the associated ergonomic risk factors. A job analysis is very important because, it can be used to successfully prevent or reduce the various MSD hazards at a workplace. The primary risk factors that should be analysed are force, posture, local contact stress, and repetition. It is also very important to consider duration and magnitude of each factor. Other risk factors that should be considered are the layout and condition of the workplace or workstation, the characteristics of the object handled, environmental conditions of the workplace (temperature, humidity, noise etc), and organization of work tasks (variety, duration of tasks).
By properly designing the activity or work station and by selecting the appropriate tools or equipment for that job, MSD hazards can be greatly avoided. Risk Factors can be avoided or reduced by using various methods:
- First, engineering controls should be considered, such as work station, improved machine and tool design.
- Second, work practices, method statements and procedures should be put in place.
- Administrative controls such as worker rotation, variety in the activities performed, more breaks etc should also be considered at this point, and
- as a last resort personal protective equipment can be used.
Management commitment and employee participation should always be a part of an effective ergonomic program. MSDs are often easy to prevent by establishing an ergonomics program in the workplace. Providing and encouraging employees to participate in the ergonomics program and in decisions affecting their safety and health is also a very import element in the success of an ergonomic program. A successful ergonomic management program should also include other elements such as Job hazard analysis, and training and education.
