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Chapter 10 Ergonomic Hazards
Major Topics • Ergonomics • Human factors • Worksite analysis • Hazard prevention and control • Training and education • Economics of ergonomics • Cumulative trauma disorders (CTDs)
Ergonomics: definition and origins • Ergonomics involves the following: • Using special design and evaluation techniques to make tasks, objects, and environments more compatible with human abilities and limitations. • Seeking to improve productivity and quality by reducing workplace stressors, reducing the risk of injuries and illnesses, and increasing efficiency. • Ergonomics is derived from the Greek language: Ergon means work and Nomos means laws, so ergonomics means work laws.
Factors Associated With Physical Stress • Sitting versus standing: Generally speaking, sitting is less stressful than standing. • Large versus small demand for strength/ power: Jobs that demand large amounts of strength/power are generally more stressful than those that require less. • Non repetitive versus repetitive motion: Repetition can lead to monotony and boredom. When this happens the potential for physical stress increases.
Human Factors and Ergonomics • Human Factors is a profession to help ensure that equipment and systems are safe and easy to operate by human beings. • 1. Predesign Analysis: Human factors professionals conduct research to determine what factors contribute to fatigue and stress and how designers can overcome these factors. • 2. Preliminary Design: Human factors professionals study machine and human capabilities to determine which tasks should be undertaken manually and which should be automated. • 3. Detail Design and Development: Human factors professionals define the environment required for operator safety, enhanced operator performance, and the reduction or prevention of operator stress and fatigue. • 4. Test and Evaluation: Human factors professionals test actual humans in using the prototype equipment or system.
Human Factors and Safety • 1. Hazard elimination by design: Intelligent design can reduce human error by providing controls that are simple to understand and operate. • 2. Provision and location of safety devices: Design and location of safety devices such as emergency cutoff switches can reduce human error on the job, correspondingly reducing the chances of an accident. • 3. Provision of warning devices: Color, location, and wording of warning devices; pitch and volume of warning signals; and the design of caution markings on gauges and video displays are all important factors in reducing the likelihood of a human error that might lead to an accident. • 4. Establishment of procedures/provision of training: When hazards cannot be designed out of a system, administrative procedures for hazard reduction must be established and training related to those procedures must be provided.
OSHA Voluntary Ergonomic Guidelines • OSHA’s ergonomic guidelines are geared towards manufacturing and materials handling in the general industry sector. They do not apply to construction, maritime operations, agriculture, or employees that operate a railroad. • This amounts to assigning responsibility for ergonomics to one individual and informing employees about the risks of MSD (musculoskeletal disorders) related injuries, symptoms of such injuries and why early reporting of symptoms is important. In addition the basic program requires employers to establish a system that employees can use to report symptoms of MSD injuries.
OSHA’s Recommended Worksite Analysis Program for Ergonomics • 1. Gather information from available sources to identify ergonomic hazards in the workplace. • 2. Conduct baseline screening surveys to determine which jobs need closer analysis – identify jobs that put employees at risk of CTD’s (Cumulative Trauma Disorders). • 3. Perform ergonomic job hazard analysis for those workstations with identified risk factors. • 4. Implement control measures, conduct periodic surveys and follow up studies to evaluate changes.
Risk Factors associated with CTDs • Repetitive and/or prolonged activities • Forceful exertions usually with the hands • Prolonged static postures • Awkward postures of the upper body, including reaching above the shoulders • Continued physical contact with work surface (WalMart cashiers) • Excessive vibration from power tools • Use of gloves
Steps in Conducting Ergonomic Job Hazard Analysis • Workstation Analysis: identify all risk factors present in each studied job or workstation. • Lifting hazards: for manual materials handling. • Videotape method: for analysis of work process. • Periodic ergonomic surveys: to identify new deficiencies. • Feedback and follow up: to identify risk factors and controls. • Trend Analysis: using several years of data –for departments, processes, job titles, or workstations. Can be used to determine which positions are most hazardous.
Hazard Prevention and Control Program • Workstation Design: to accommodate the person who actually use them. • Design of Work Methods: Static postures and repetition rates should be supplemented by addressing force levels on the hand and arm postures involved (to reduce CTDs). • Tool Design and Handles: Tools should be selected and designed to minimize the risk of upper extremity CTDs and back injuries. Variety of sizes should be available.
Participation in Ergonomics Training Program • All employees including supervisors and other plant management personnel on the different types of CTDs and means of prevention, causes, early symptoms, and treatment of CTDs. • This information should be reinforced during workplace walkthroughs and the individual health surveillance appointments. • All new employees should be given such training during orientation. This will facilitate early recognition of CTDs, and increase the likelihood of compliance with prevention and treatment.
Common Indicators of Ergonomic Problems • Apparent Trends in Accidents and Injuries: A pattern or high incidence rate of a specific type of injury indicates that an ergonomic problem exits. • Incidence of Cumulative Trauma Disorders ( CTDs): By observing workplace that include a high level of repetitive work, hand force, awkward posture, vibration, mechanical stress, extreme temperatures. • Absenteeism and High Turnover Rates: indicators of ergonomic problems. • Employee Complaints: high incidence can indicate ergonomic problems. • Employee Generated Changes: workplace additions can be evidence of ergonomic problems. • Poor Quality: can be indicator of ergonomic problems. • Manual Material Handling: lifting large objects, bulky objects, lifting objects from the floor, and lifting frequently.
Identifying Specific Ergonomic Problems • General Observation: be attentive to tasks requiring manual material handling and repetitive movements. • Questionnaires and Interviews: Questionnaires are easy to distribute, tabulate and analyze. Interviews provide more in depth information. • Videotaping and Photography: records work being done without being intrusive. • Drawing or Sketching: can help identify problems. • Measuring the Work Environment: how far must a worker carry the material manually. How high does a worker have to lift a object. How much does an object weigh. • Understanding the Ergonomics of Aging: adapt the job to the person. Range of motion begins to diminish by age 45. Lower back pain is more common in people over 45.
Ergonomic Problem Solving Strategies • Seated Repetitive Work With Light Parts: Back, neck, shoulder, and lower leg pain are common. Include other work tasks to break the monotony of repetition. Use adjustable chair. • Work with Hands above the Chest: Neck, upper body and heart strain. Eliminate manual lifting to the extent possible by raising work floor or using lifts. • Work with Hand Tools: Carpel tunnel syndrome (CTDs), and muscle strains of the lower arm, hands and wrist. Improve hand positions during use of tools, enhance worker’s grip on tools, and minimize amount of twisting involved.
Research Concerning Economics of Ergonomics • Such research is often more complex and extensive than safety and health measures that have been undertaken. • Many decision makers think such studies are irrelevant because promoting safety and health is enough.
Define CTD. Explain the Most Common Types • Cumulative Trauma Disorders is a term that covers a number of injuries caused by forceful or awkward movements repeated frequently over time. CTDs occur to the muscles, nerves, and tendons of the hands, arms, shoulder and neck. • Muscle and Tendon Disorders: Tendons connect muscle to bones. Tears can become inflamed and cause intense pain called tendinitis. • Cervical Radiculopathy: Holding a telephone receiver while typing – compression of cervical disc of neck, making it painful to turn the head. • Tunnel Syndromes: Damage to soft tissue can cause swelling that compresses the nerves that pass through the tunnel – most common carpel tunnel syndrome. • Nerve and Circulation Disorders: Friction or inflammation cause swelling, nerves and arteries are compressed, restricting flow of blood to muscles. Result is pain in entire arm, numbness, coldness and weakness of arm, hand and fingers.
Summary • Ergon means work in Greek language and nomos means laws. • OSHAs guidelines include: worksite analysis, hazard prevention, and training and education. • Indicators of ergonomics problems are: trends in accidents and injuries, absenteeism, high turnover rates, and poor quality. • Procedures for identifying problems are: questionnaires, interviews, videotaping, and measuring. • Ergonomic improvements should not have to be justified on the basis of cost effectiveness.
Homework • Do questions 1,7, 8, and 9 on pages 231-232. • 1. Define the term ergonomics. Explain its origins. • 7. Briefly explain the steps in conducting an ergonomic job hazard analysis. • 8. Briefly explain the components of a hazard prevention and control program. • 9. Who should participate in an ergonomic training program?