Search NIOSH | NIOSH Home | NIOSH Topics | Site Index | Databases and Information Resources | NIOSH Products | Contact Us |
NIOSH Publication No. 2007-131:Ergonomic Guidelines for Manual Material Handling |
April 2007 |
|
|
OverviewManual material handling (MMH) work contributes to a large percentage of the over half a million cases of musculoskeletal disorders reported annually in the United States. Musculoskeletal disorders often involve strains and sprains to the lower back, shoulders, and upper limbs. They can result in protracted pain, disability, medical treatment, and financial stress for those afflicted with them, and employers often find themselves paying the bill, either directly or through workers’ compensation insurance, at the same time they must cope with the loss of the full capacity of their workers. Scientific evidence shows that effective ergonomic interventions can lower the physical demands of MMH work tasks, thereby lowering the incidence and severity of the musculoskeletal injuries they can cause. Their potential for reducing injury related costs alone make ergonomic interventions a useful tool for improving a company’s productivity, product quality, and overall business competitiveness. But very often productivity gets an additional and solid shot in the arm when managers and workers take a fresh look at how best to use energy, equipment, and exertion to get the job done in the most efficient, effective, and effortless way possible. Planning that applies these principles can result in big wins for all concerned. Content:About This Booklet
About this BookletThis booklet is written for managers and supervisors in industries that involve the manual handling of containers. It offers suggestions to improve the handling of rectangular, square, and cylindrical containers, sacks, and bags. "Improving Manual Material Handling in Your Workplace" lists the benefits of improving your work tasks. It also contains information on risk factors, types of ergonomic improvements, and effective training and sets out a four-step proactive action plan. The plan helps you identify problems, set priorities, make changes, and follow up. Sections 1 and 2 of "Improvement Options" provide ways to improve lifting, lowering, filling, emptying, or carrying tasks by changing work practices and/or the use of equipment. Guidelines for safer work practices are also included. Section 3 of "Improvement Options" provides ideas for using equipment instead of manually handling individual containers. Guidelines for safer equipment use are also included. For more help the "Resources" section contains additional information on administrative improvements, work assessment tools and comprehensive analysis methods. This section also includes an improvement evaluation tool and a list of professional and trade organizations related to material handling. Improving Manual Material Handling in your WorkplaceWhat Manual Material Handling IsAccording to the U.S. Department of Labor, handling is defined as: Seizing, holding, grasping, turning, or otherwise working with the hand or hands. Fingers are involved only to the extent that they are an extension of the hand, such as to turn a switch or to shift automobile gears. In this publication, handling means that the worker’s hands move individual containers manually by lifting, lowering, filling, emptying, or carrying them.
Why Improve Your WorkplaceManual handling of containers may expose workers to physical conditions (e.g., force, awkward postures, and repetitive motions) that can lead to injuries, wasted energy, and wasted time. To avoid these problems, your organization can directly benefit from improving the fit between the demands of work tasks and the capabilities of your workers. Remember that workers’ abilities to perform work tasks may vary because of differences in age, physical condition, strength, gender, stature, and other factors. In short, changing your workplace by improving the fit can benefit your workplace by:
What to Look ForManual material handling tasks may expose workers to physical risk factors. If these tasks are performed repeatedly or over long periods of time, they can lead to fatigue and injury. The main risk factors, or conditions, associated with the development of injuries in manual material handling tasks include:
Repeated or continual exposure to one or more of these factors initially may lead to fatigue and discomfort. Over time, injury to the back, shoulders, hands, wrists, or other parts of the body may occur. Injuries may include damage to muscles, tendons, ligaments, nerves, and blood vessels. Injuries of this type are known as musculoskeletal disorders, or MSDs. In addition, poor environmental conditions, such as extreme heat, cold, noise, and poor lighting, may increase workers’ chances of developing other types of problems. Types of Ergonomic ImprovementsIn general, ergonomic improvements are changes made to improve the fit between the demands of work tasks and the capabilities of your workers. There are usually many options for improving a particular manual handling task. It is up to you to make informed choices about which improvements will work best for particular tasks. There are two types of ergonomic improvements:1. Engineering ImprovementsThese include rearranging, modifying, redesigning, providing or replacing tools, equipment, workstations, packaging, parts, processes, products, or materials (see “Improvement Options”). 2. Administrative ImprovementsObserve how different workers perform the same tasks to get ideas for improving work practices or organizing the work. Then consider the following improvements:
Administrative improvements, such as job rotation, can help reduce workers’ exposures to risk factors by limiting the amount of time workers spend on “problem jobs.” However, these measures may still expose workers to risk factors that can lead to injuries. For these reasons, the most effective way to eliminate “problem jobs” is to change them. This can be done by putting into place the appropriate engineering improvements and modifying work practices accordingly. TrainingTraining alone is not an ergonomic improvement. Instead, it should be used together with any workplace changes made. Workers need training and hands-on practice with new tools, equipment, or work practices to make sure they have the skills necessary to work safely. Training is most effective when it is interactive and fully involves workers. Below are some suggestions for training based on adult learning principles:
A Proactive Action PlanManual material handling jobs require movement and physical activity. But how do you find out:
One way to answer these questions is to be proactive in your problem solving. Being proactive simply means finding the problems first by looking thoroughly around the workplace rather than waiting for problems to occur. Then improve the fit between the work and the worker by putting the appropriate changes into place. The process includes involving workers, observing jobs, making decisions on effective options, and then taking action. It is important to involve workers, managers, and supervisors throughout the process. There are four steps to a proactive action plan:
Step 1: Look for Cluesa. Review written records (e.g., OSHA Log 300, past worker reports or complaints, and workers’ compensation reports). Your workers’ compensation insurance carrier may offer risk-management services that can provide workplace assessment surveys. b. Observe work activities. Talk to workers, supervisors, and managers about where problems exist. Look for warning signs, such as:
Make sure to talk to your workers about their ideas for altering work processes, operations, tools, or equipment. Ask them how they would make their jobs less physically demanding and more efficient. c. Use assessment tools - To determine where problems may arise in work tasks, you may want to use some of the following simple “tools” (see Appendix B):
If the problems are complex, more sophisticated methods may be needed for addressing your workplace MSDs. More detailed assessment tools for specific problems include the following (see Appendix C):
Step 2: Prioritize Jobs for ImprovementsAfter detecting the problems, decide which tasks to improve and then set priorities. Consider:
Step 3: Make ImprovementsThe goal of making changes is to improve the fit between the demands of work tasks and the capabilities of your workers. Combine operations and processes whenever possible to reduce or eliminate unnecessary manual handling of materials and products. Depending on the characteristics of the work and the workers, there may be some changes that will improve a particular task. For suggestions on how to improve your work tasks, see "Improvement Options." Appendix D contains a tool to help evaluate the improvements you are considering. If you need additional help with improvements, consider the following:
Step 4: Follow UpIt is important to follow up in order to evaluate if your improvements have worked. After a reasonable adjustment period, set a date to follow up on the changes made. Make sure to evaluate each improvement separately for effectiveness. The following questions may be helpful: Has each improvement:
If you determine that your improvements have not worked, modify them or try something different until the risk factors have been reduced or eliminated. Improvement OptionsEasier Ways to Manually Lift, Lower, Fill, or Empty ContainersConsider the following options that will:
NIOSH Lifting EquationThe Revised National Institute of Occupational Safety and Health (NIOSH) Lifting Equation (1994) provides guidelines for evaluating two-handed manual lifting tasks. It defines a Recommended Weight Limit (RWL) as the weight of the load that nearly all healthy workers can lift over a substantial period of time (e.g., eight hours) without an increased risk of developing lower back pain. The maximum weight to be lifted with two hands, under ideal conditions, is 51 pounds. The RWL is based on six variables that reduce the maximum weight to be lifted to less than 51 pounds. Consult the Revised NIOSH Lifting Equation (1994) for information to help assess complex lifting tasks (see Appendix C). Note: The lifting guidelines suggested by the Revised NIOSH Lifting Equation are not Cal/OSHA regulatory requirements and are not part of Title 8 of the California Code of Regulations. Management Guidelines for Safer Lifting
Employee Guidelines for Safer Lifting
Easier Ways to Manually Carry ContainersConsider the following options that will:
Management guidelines for safer carrying
Employee Guidelines for Safer Carrying
Alternatives to Manual Handling of Individual Containers
Guidelines for Equipment Use
Work Environment
Work Practices
ResourcesAppendix A. Administrative ImprovementsAdministrative improvements include changing work practices or the way work is organized. Administrative improvements require continual monitoring by management and employee feedback to make sure the improvements are effective. Provide variety in jobsThere are a couple of ways to increase variety in jobs. Job rotation means rotating employees through different jobs. Job enlargement means increasing the variety by combining two or more jobs or adding tasks to a particular job. To be effective, both improvements rely on changing jobs and tasks so that they differ in the:
Adjust work schedules and work paceNew workers who are not used to the physical demands of the job or those returning from long absences should be gradually introduced to a normal work pace and workload like an athlete in spring training. Provide recovery timeRecovery periods (i.e., muscle relaxation periods) can help prevent fatigue and injury to muscles. Several short breaks can reduce the frequency and duration of physically demanding activities. Ask employees for their ideas for the best rotation or break schedules to reduce the physical demands of their jobs. Their suggestions can help you integrate the physical demands of jobs with the environmental and organizational demands of the workplace. Modify work practicesPay close attention to how the work is being performed. Employees should be encouraged to be comfortable, change positions, and stretch during work periods. The human body is stronger, more efficient and less prone to injury when work is performed in midrange postures and within the power zone. Midrange postures mean postures in which the joints of the neck, back, legs, arms, and wrists are not bent in extreme positions. The power zone is above the knees, below the shoulders, and close to the body. The principle of the power zone is that in this area workers have the greatest power to perform heavier work tasks with less bending, stooping, or reaching. Appendix B. Assessment “Tools”NIOSH Manual Material Handling (MMH) ChecklistElements to Ergonomics This checklist is not designed to be a comprehensive risk assessment technique but rather as a tool to quickly identify potential problem jobs. Additional risk factors may exist that are not accounted for in this checklist. It is common practice to follow up checklist observations with more precise techniques to confirm problem risk factors. "No" responses indicate potential problem areas that should be investigated further.
Hazard Evaluation Checklist for Lifting, Carrying, Pushing, or PullingThis checklist is not designed to be a comprehensive risk assessment technique but rather as a tool to quickly identify potential problem jobs. Additional risk factors may exist that are not accounted for in this checklist. It is common practice to follow up checklist observations with more precise techniques to confirm problem risk factors. "Yes" responses are indicative of conditions that pose a risk of developing low back pain. The larger the percentage of “Yes” responses that are noted, the greater the possible risk. Source: T. R. Waters, “Manual Materials Handling”, in: Physical and Biological Hazards of the Workplace (Second edition). Edited by P. Wald and G. Stave. New York: John Wiley and Sons, 2002.
Ergonomics Awareness WorksheetThe purpose of the worksheet is to increase basic awareness of potential problems associated with jobs and tasks. This awareness can help provide clues on how to make effective improvements. Job Title:
adapted from EasyErgonomics: A Practical Approach for Improving the Workplace .Sacramento California Department of Industrial Relations, Cal/OSHA Consultation Service, Research and Education Unit, 1999.
Ergonomics Checklist — Material HandlingThe checklist presented below is from the book Kodak's Ergonomic Design for People at Work (adapted from material developed by the Chemical Manufacturers Association). It helps users to identify any job risk factors that may be present in the job. This checklist is applicable to jobs requiring the routine handling of objects of 10 pounds or more.
Job/Task: __________________________________ Before After (Controls Implemented) Directions: Review each condition for the job/task of interest and for each condition that frequently occurs, place an X in the “Concern” column as appropriate. Add comments as appropriate.
Appendix C. Analysis MethodsThe following methods are comprehensive tools designed to provide a detailed analysis of various types of manual material handling tasks. They can be used to evaluate lifting, lowering, pushing, pulling, carrying, and other activities. NIOSH Lifting EquationThe NIOSH Lifting Equation is a tool used to evaluate manual lifting tasks. This equation allows the user to insert the exact conditions of the lift (e.g., height, distance lifted, weight, position of weight relative to body, etc.). This equation accounts for asymmetrical lifts and objects that are difficult to grasp. http://www.cdc.gov/niosh/94-110.html ACGIH Threshold Limit Values (TLVs) for LiftingThe American Conference of Governmental Industrial Hygienists (ACGIH) recommends guidelines for safe lifting. The Threshold Limit Values (TLVs) for lifting recommend upper and lower limits based upon frequency, duration, and other risk factors associated with lifting. The following ACGIH Publications may be helpful: TLVs and BEIs (#0106) Lifting: TLV Physical Agents (7th Edition) Documentation (#7DOC-734) To purchase publications, go to www.acgih.org/store or call (513) 742-2020. University of Michigan 3D Static Strength Prediction Program3D Static Strength Prediction Program software predicts static strength requirements for tasks such as lifts, presses, pushes, and pulls. The program provides an approximate job simulation that includes posture data, force parameters, and male/ female anthropometry. The results include the percentage of men and women who have the strength to perform the described job, spinal compression forces, and data comparisons to NIOSH guidelines. The user can analyze torso twists and bends and make complex hand force entries. Analysis is aided by an automatic posture generation feature and three-dimensional human graphic illustrations. http://www.engin.umich.edu/dept/ioe/3DSSPP/ Ohio State Lumbar Motion MonitorTraditionally, most workplace ergonomic assessments have focused on joint loading in static postures. However, epidemiologic studies have shown that three-dimensional dynamic motion is associated with an increased risk of occupational injury and illness. The Bio dynamicsLab has developed a unique research program that focuses on the study of occupational joint loading under realistic dynamic motion conditions. The program's goal is to obtain a better understanding of how much exposure to realistic risk factors is too much. http://biodynamics.osu.edu/research.html Snook's Psychophysical TablesThese tables are based on psychophysical data and provide the maximum acceptable weights and forces for various common tasks including lifting and lowering weights, pulling and pushing forces, and carrying objects. Values are given for different lift heights, number of lifts per minute, and percentiles of male and female populations capable of the task. S. H. Snook, and V. M. Ciriello. “The Design of Manual Handling Tasks: Revised Tables of Maximum Acceptable Weights and Forces.” Ergonomics 34(9): 1197–1213 (1991). NIOSH Publications on Ergonomics and Musculoskeletal Disorders (MSDs)NIOSH offers many types of publications including: Appendix D. Improvement Evaluation “Tools”As you evaluate possible improvement options, keep in mind the requirements that are most important in your particular workplace. Then, ask the following general questions for each improvement option under consideration: Will this improvement:
Appendix E. OrganizationsThe following organizations may provide additional information on material handling equipment and work practices. American National Standards Institute (ANSI)ANSI coordinates the U.S. voluntary consensus standards system, approves American National Standards, and is the sole U.S. representative and dues-paying member of the International Organization for Standardization and the IEC. American Production and Inventory Control Society (APICS)APICS — The Educational Society for Resource Management is a not-for-profit international educational organization that offers education and professional certification programs. American Society of Mechanical Engineers (ASME)ASME membership includes opportunities to share new concepts, spearhead solutions, and advance the science and practice of mechanical engineering through the programs of its 36 technical divisions and four institutes. ASME International is a nonprofit educational and technical organization serving a worldwide membership of 125,000. Association of Professional Material Handling Consultants (APMHC)APMHC is a professional society composed of individual consultants in the material-handling field. www.mhia.org/PS/PS_APMHC_WhatIsAPMHC.cfm The Automated Material Handling Systems AssociationFor over 27 years, the Automated Materials Handling Systems Association (formerly Automated Storage Retrieval Systems/Automatic Guided Vehicle Systems Users' Association) has promoted the sharing of knowledge and experience among its members, both users and vendors, to provide proven solutions to common warehousing/automation problems. College-Industry Council on Materials Handling Education (CICMHE)The council provides information, teaching materials, and various events in support of education and research on material handling. www.mhia.org/et/ET_MHI_CICMHE_Home.cfm Conveyor Equipment Manufacturers Association (CEMA)CEMA's purpose is to promote voluntary standardization of conveyor design, manufacture, and application. Council of Supply Chain Management Professionals (CSCMP)Council of Supply Chain Management Professionals seeks to enhance the development of the logistics profession by providing information and educational opportunities. Darcor and Ergoweb ® Ergonomic White PaperThe Ergonomics of Manual Material Handling - Pushing and Pulling Tasks Fédération Européenne de la Manutention (FEM)FEM is the European manufacturers association of materials handling and lifting and storage equipment. It represents the technical, economic, and political interests of the industry. FEM serves technical progress and improves safety at work through the establishment of guidelines and business codes. Industrial Truck Association (ITA)ITA's site includes directory of members' products by truck class, information on vendor-sponsored operator training programs, data on standards for trucks and parts, events of the lift-truck industry, annual statistics on U.S. shipments of industrial trucks, and more. Institute of Industrial Engineers (IIE)The IIE is a professional society dedicated to advancing the technical and managerial excellence of those concerned with improving the productivity of integrated systems of people, materials, information, equipment, and energy. The IIE serves the professional needs of industrial engineers and all individuals involved with improving quality and productivity. International Warehouse Logistics Association (IWLA)The IWLA is the unified voice of the global logistics outsourcing industry, representing third-party warehousing, transportation, and logistics service providers. Material Handling Equipment Distributors Association (MHEDA)The Material Handling Equipment Distributors Association (MHEDA) is the only trade association dedicated solely to improving the proficiency of the independent material-handling equipment distributor. Material Handling Industry of America (MHIA)The MHIA is the nonprofit umbrella organization overseeing its two membership divisions: The Material Handling Institute (MHI) and the Material Handling Industry of America (MHIA). This vendor association's site includes a directory of MHIA members and its products as well as information on available literature. The Material Handling Institute is the educational wing of the MHIA. The following are product sections or councils within the MHIA: Automated Storage/Retrieval Systems (AS/RS) Automatic Guided Vehicle Systems (AGVS) Conveyor Product Section (CPS) Crane Manufacturers Association of America, Inc. (CMAA) Ergonomic Assist Systems and Equipment(EASE) Hoist Manufacturers Institute (HMI) Institute of Caster Manufacturers (ICWM) Integrated Systems & Controls Council (ICS) Lift Manufacturers Product Section (LMPS) Loading Dock Equipment Manufacturers (LODEM) Monorail Manufacturers Association, Inc. (MMA) Order Fulfillment Council (OFC) Reusable Plastic Container and Pallet Association (RPCPA) Storage Equipment Manufacturers Association (SMA) Materials Handling & Management Society (MHMS)The MHMS is an individual membership organization for the materials-handling practitioner and the materials-handling community. www.mhia.org/PS/PS_MHMS_Home.cfm National Association of Manufacturers (NAM)The NAM is the nation's largest industrial trade association, representing small and large manufacturers in every industrial sector and in all 50 states. National Wooden Pallet & Container Association (NWPCA)The NWPCA is dedicated to the success of its members by helping them create cost-effective, environmentally responsible solutions to meet their customers' changing unit load handling needs. Packaging Machinery Manufacturing Institute (PMMI)The PMMI is a resource for packaging. PMMI's mission states that it is committed to improving, leading, and unifying all segments of the packaging industry worldwide. Robotics Industries Association (RIA)The RIA is North America's only trade association focused exclusively on robotics. More than 250 member companies represent leading robot manufacturers, system integrators, end users, and researchers. Society of Manufacturing Engineers (SME)The Society of Manufacturing Engineers is a nonprofit, professional society dedicated to the advancement of scientific knowledge in the field of manufacturing engineering. SME is a professional society serving the manufacturing industries. SME has some 60,000 members in 70 countries and supports a network of hundreds of chapters worldwide. Supply-Chain Council (SCC)The Supply-Chain Council's membership is primarily practitioners representing a broad cross-section of industries, including manufacturers, services, distributors, and retailers. University of California Agricultural Ergonomics Research Center, UC DavisThis center's mission is to understand and apply ergonomic approaches to the development and evaluation of equipment designs and work practices that prevent musculoskeletal disorders in agricultural work<. The "pot lifter" was developed to lift and carry pots and other cylindrical containers. For
detailed information on this device, go to http://ag-ergo.ucdavis.edu
Warehousing Education and Research Council (WERC)The Warehousing Education and Research Council (WERC) is the professional association for those in warehousing and distribution. WERC is a not-for-profit organization with more than 4,000 individual members AcknowledgementsWriters and EditorsZin Cheung, MS, CIE - Cal/OSHA Consultation Service - Sacramento, CA Mario Feletto, MS, MPH - Cal/OSHA Consultation Service - Sacramento, CA Jim Galante - EASE Council - Charlotte, NC Tom Waters, PhD, CPE - NIOSH - Cincinnati, OH Page Layout and DesignJitan Patel - Cal/OSHA Consultation Service - Sacramento, CA Photographers and Image EditorsZin Cheung, MS, CIE - Cal/OSHA Consultation Service - Sacramento, CA Rick Hight - Cal/OSHA Consultation Service - Sacramento, CA Ken Jackson - Link One LLC - Sacramento, CA Jitan Patel - Cal/OSHA Consultation Service - Sacramento, CA Fran Wagner, MS, CIE - Link One LLC - Sacramento, CA EditorFaye Ong - CDE Press, California Department of Education - Sacramento, CA Ergonomics ConsultantsSuzanne H. Rodgers, PhD - Consultant in Ergonomics - Rochester, NY Fran Wagner, MS, CIE - Link One LLC - Sacramento, CA Editorial and Technical ReviewersDave C. Bare, CIH - Cal/OSHA Consultation Service - Sacramento, CA David Brodie, MS, CPE - Atlas Ergonomics - Grand Haven, MI Paul R. Burnett - Santa Clara Valley Water District - San Jose, CA Fadi Fathallah, PhD - University of California - Davis, CA Sean Gallagher, PhD, CPE - NIOSH - Pittsburgh, PA Daniel J. Habes, MSE, CPE - NIOSH - Cincinnati, OH John Howard, MD, MPH, JD, LL.M - NIOSH - Washington, DC Ira Janowitz, PT, CPE - University of California - Berkeley, CA Brian Roberts, C.S.P., CIE - CNA Insurance - Chicago, IL Kristy Schultz, MS, CIE - State Compensation Insurance Fund - Sacramento, CA Steve Smith, CIH - Division of Occupational Safety & Health - Sacramento, CA Len Welsh, MS, JD - Division of Occupational Safety & Health - Sacramento, CA ContributorsWe thank the following people and organizations for their support and assistance in the development of this publication: Denny Albrecht - BMH Equipment, Inc. - Sacramento, CA Jim Borman - Signode Western Operations - Pittsburg, CA Delia Deas - Tropicana - City of Industry, CA Linda Donavon - Eagle Group - Clayton, DE Ken Fletcher - Blue Diamond Growers - Sacramento, CA Herman Jett - Cal/OSHA Consultation Service - Santa Fe Springs, CA Mike Kelly - Calgene - Davis, CA Ken King - SPC Industrial - Holly, MI Rory Manley - General Pool and Spa - Rancho Cordova, CA Etta Mason - Southern California Edison -Westminster, CA Brad McCroskey - Triple A Containers - Cerritos, CA Edward D. Page - Office of State Publishing - Sacramento, CA Iraj Pourmehraban - Cal/OSHA Consultation Service, VPP - Oakland, CA Fred Sibley - Natural Stone - Sacramento, CA We thank the following companies for contributing to the development of this publication:
Cal/OSHA Consultation Programs
|
|
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||