This paper examines the field of ergonomics—its definition, goals, and practical application in workplace settings. Drawing on case studies from the United States Postal Service and broader occupational health research, the paper explores how manual handling tasks contribute to musculoskeletal injuries, particularly lower back injuries. It discusses NIOSH health hazard evaluations of automated mail processing machines, identifies ergonomic risk factors such as repetitive motion, awkward postures, and forceful exertion, and argues that fitting the work environment to the worker—rather than the reverse—improves both worker safety and overall productivity.
Ergonomics, also known as human factors, is the scientific discipline concerned with understanding the relationships between humans and other elements of a system. As a profession, it applies theory, principles, data, and methods to design in order to optimize human comfort and overall system performance. Ergonomists contribute to the design and assessment of tasks, jobs, products, environments, and systems in order to make them compatible with the needs, abilities, and limitations of people (Helander, 2006).
Ergonomics is further defined as the design of the workplace, equipment, machines, tools, products, environments, and systems — taking into consideration the human's physical, physiological, biomechanical, and psychological capabilities — while optimizing the effectiveness and productivity of work systems and assuring the safety, health, and wellbeing of workers (Fernandez, 1995). In general, the fundamental aim of ergonomics is to fit the task to the individual person, not the individual person to the task.
Low back injuries, often resulting from improper manual handling of materials, form the largest subset of musculoskeletal injuries. The seriousness of the lower back injury problem is reflected in the large number of claims filed under the US Worker's Compensation Act of 1970. The National Safety Council has reported that in the United States, 400,000 workers suffer disabling back injuries every year. Statistics also show that back injuries resulting from manual materials handling (MMH) activities are a major source of lost work time and compensation claims. Back injuries alone cost industry an estimated US$14 billion per year (Fernandez, 1995).
In common with other industries, the most frequent cause of injuries and accidents in the Post Office is manual handling of one sort or another. Following the introduction of the Manual Handling Operations Regulations in 1992, members of the ergonomics group became involved in assessing and reducing the risks associated with all manual handling activities. There was a concerted effort to eliminate all high-risk tasks through the introduction of new and improved equipment and working methods. One of the keys to the success of this initiative was the breadth of operational knowledge within the ergonomics group and the way in which it worked with frontline managers, staff, and unions. This collaboration proved essential in arriving at realistic solutions that were both operationally and ergonomically acceptable (Dillon, 1999).
Manual letter sorting poses relatively little risk for musculoskeletal disorders. However, work on automatic mail processing machines is potentially hazardous to employees due to design flaws and the high-volume capacities of these machines. Under moderate mail volume conditions, the feeder positions on the OCR, BCS, and DBCS machines could be improved by providing a mechanism to reduce trunk flexion while retrieving trays of mail from mail carriers. The sweep positions on the OCR and BCS machines could be made safer by redesigning the workstation to reduce the amount of trunk flexion and arm reaching (HHE Report No. HETA-92-0073-2337, United States Postal Service, General Mail Facility, Denver, Colorado, 1993).
"NIOSH investigation of ergonomic hazards in Denver postal facility"
"Research linking job risk factors to musculoskeletal disease"
"Ergonomics improving safety, efficiency, and worker productivity"
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