ERGONOMICS
The term 'ergonomics' was first used in the 1950s. It comes from the Greek words ergos (work) and nomos (measurement). Ergonomics is the study of the interactions between the worker, the job, and the environment. The aim of ergonomics is to help people work efficiently-not only striving toward short-term effectiveness but also eliminating longer-term detrimental effects on health and minimizing the risk of accidents.
The goals of ergonomics are:
- Decrease in incidence and severity of CTD
- Increased quality and productivity
- Improved morale
This article considers design factors, training, and maintenance. It also contains a checklist for evaluating your ergonomics and cumulative trauma diseases (CTD) program.
OSHA Ergonomics Guides
The Occupational Safety and Health Administration (OSHA) has developed draft ergonomic guidelines and rules. A new revision, due to be out later this year, will include back and lower extremity ergonomics and an easy-to-use description of the NIOSH lifting guidelines.
Major facets of ergonomics are:
- Workplace design
- Employee training
- Equipment and environment maintenance
DESIGN FACTORS include the layout of workspaces; the workplace environment; and worker interfaces with tools, materials, and coworkers.
TRAINING includes general ergonomic awareness and specific training for effective task performance.
MAINTENANCE of equipment and the workplace environment is an important aspect of ergonomics. Without proper, well-maintained equipment and material, a job can become more difficult and even hazardous.
Anthropometric Design
After averaging the characteristics of a wide variety of people, workplaces can be designed to accommodate 90% of the population. Systems such as chairs and workbenches should be adjustable to accommodate different sizes of people. Shelves can be designed so that they are within the reasonable reach of 10th percentile height of people, and enclosed areas large enough for the 90th percentile size of person.
ADA and other requirements may call for further accommodations for specific employees, but design beyond the 90% accommodation is usually not practical or economically feasible.
Workplace Design
- Keep all materials and controls in front of the employee.
- Keep work surfaces at an appropriate height.
- Provide chairs that adjust and swivel.
- Avoid twisting and lateral bending.
- Minimize stooping.
- Avoid reaching behind the body.
- Avoid static postures.
- Encourage frequent posture changes.
- Baffle noises.
- Provide appropriate lighting without glare.
Cumulative Trauma Disorders
Cumulative trauma disorders (CTD) account for more than half of work-related illnesses and injuries. Costs are estimated to exceed $100 billion per year. The rapid increase in these injuries (nine fold over the past 10 years) may be due to increased acceptance of these injuries as work related.
The most frequent complaints involve tendons, muscles, and nerves of the upper extremities and torso. Illnesses include tendinitis, carpal tunnel syndrome, and muscle strains.
Causes
The causes of CTD include repetitive motions, forceful exertions, work in awkward postures, mechanical stress, vibration, exposure to low temperatures, pressure from hard work surfaces or sharp edges, and unaccustomed work activities.
Repetitive tasks
Silverstein et al. have described a class of jobs that have high repetition rates and can lead to fatigue and injury. These jobs require repetitive muscle effort without providing adequate recovery time. According to their definition, a highly repetitive job can be characterized by one of the following:
- A cycle time less that 30 seconds
- More than 1,000 parts per shift
- More than 50% of the cycle time involving the same kind of fundamental cycle.
Ergonomic stress from repetitive tasks can be reduced by decreasing production rates, changing methods, automation or providing mechanical assistance, and worker rotation.
Force Requirements
Some jobs require high forces and do not provide recovery time for soft body tissues. Pounding can cause mechanical stress. To avoid force related injuries:
- Use power tools and assists.
- Use power grip rather than pinching grips.
- Spread the force.
- Use jigs and fixtures.
- Avoid slippery, sharp or hard surfaces.
Cures
The basic methods for reducing the risk of CTD are:
- Ergonomic design of workplaces
- Employee training
- Administrative controls
Ergonomic approaches include:
- Anthropometric design
- Reducing repetitions
- Reducing force requirements
- Eliminating awkward postures
- Protective equipment) wrist supports, back belts, etc.)
Ergonomic training includes:
- Employee awareness
- Job and task training
- Reporting and correcting problems
Administrative controls include:
- Job rotation, job sharing, and job enlargement
- Work/rest cycles and exercise
- Employee job empowerment
CTD Reduction Programs
Employers need an ergonomic approach to workplace illness and injury prevention. An effective program not only affects employee welfare but has positive impact on corporate profits. One program documented a 42% reduction incidents and savings of almost half a million in labor costs. The following checklist will help you assess your CTD program.
CTD Checklist
Planning:
[ ] Is there a written CTD plan?
[ ] Does the plan specify responsible persons and organizations?
[ ] Does the plan specify data collection and analysis?
[ ] Does the plan provide for response to CTD incidences?
[ ] Does the plan specify corrective actions?
[ ] Does the plan provide for follow-up and analysis?
[ ] Does the plan specify training?
[ ] Does the plan provide for employee testing?
[ ] Does the plan provide for job site and workstation testing?
[ ] Does the plan specify protective equipment?
[ ] Does the plan provide administrative controls?
[ ] Does the plan specify engineering evaluation and changes?
Training
[ ] Are all new employees trained to avoid CTD risks?
[ ] Are employees trained when their job activities are changed?
[ ] Does training cover symptoms of CTD?
[ ] Does training describe CTD risk factors?
[ ] Does CTD training include selection and use of protective equipment?
[ ] Does training explain CTD medical management?
[ ] Does training include basic ergonomic information?
[ ] Are employees provided information on CTD reporting procedures?
[ ] Does the training system include time for questions and answers about CTD and job safety?
Identifying and correcting problems:
[ ] Have past claims been analyzed?
[ ] Have administrative changes been made to prevent recurrence where appropriate?
[ ] Have engineering changes been made to prevent recurrence where appropriate?
[ ] Is there ongoing surveillance to identify potential problems?
[ ] Is there a system to make engineering changes to eliminate potential problems?
[ ] Is there a system to make administrative changes to eliminate potential problems?
[ ] Is there a reporting program for CTD-related problems?
[ ] Is there a system to make administrative changes to prevent recurrence where appropriate?
[ ] Is there a system to make engineering changes to prevent recurrence where appropriate?
[ ] Is CTD problem identification and correction a regular specified activity of the safety committee?
Responding to Incidents
[ ] Are incidents reported promptly?
[ ] Is there competent medical evaluation?
[ ] Is there appropriate analysis?
[ ] Is there ergonomic analysis of CTD problems?
[ ] Are problems evaluated?
[ ] Is treatment provided?
[ ] Is follow-up evaluation and treatment provided?
[ ] Are changes made to prevent recurrence?
[ ] Are alternative work programs available to employees returning from CTD illnesses?
Reprinted with permission from Safety Information Currents.