S. Revathy

epgp books








To analyze the ergonomic hazards at work place






Ergonomics is the science of designing the workplace, keeping in minds the capabilities and limitations of the worker. Poor worksite design leads to fatigued, frustrated and hurting workers. This rarely leads to the most productive worker. More likely, it leads to a painful and costly injury, lower productivity and poor product quality. Ergonomics derives from two Greek words: ergon, meaning work, and nomoi, meaning natural laws, to create a word that means the science of work and a person’s relationship to that work. The term “ergonomics” is derived from two Greek words: “ergon,” meaning work, and “nomoi,” meaning natural laws. Ergonomists study human capabilities in relationship to work demands.


Ergonomics is the process of designing or arranging workplaces, products and systems so that they fit the people who use them. At its simplest definition ergonomics, it literally means the science of work. So ergonomists, i.e. the practitioners of ergonomics, study work, how work is done and how to work better. It is the attempt to make work better that ergonomics becomes so useful. And that is also where making things comfortable and efficient comes into play. Ergonomics is commonly thought of in terms of products. But it can be equally useful in the design of services or processes.


Most people have heard of ergonomics and think it is something to do with seating or with the design of car controls and instruments – and it is… but it is so much more. Ergonomics applies to the design of anything that involves people – workspaces, sports and leisure, health and safety.


Ergonomics (or ‘human factors’ as it is referred to in North America) is a branch of science that aims to learn about human abilities and limitations, and then apply this learning to improve people’s interaction with products, systems and environments. Ergonomics aims to improve workspaces and environments to minimize risk of injury or harm. So as technologies change, so too does the need to ensure that the tools we access for work, rest and play are designed for our body’s requirements.


Ergonomics is a relatively new branch of science which celebrates its 50th anniversary in 1999, but relies on research carried out in many other older, established scientific areas, such as engineering, physiology and psychology. To achieve best practice design, Ergonomists use the data and techniques of several disciplines:

  • anthropometry: body sizes, shapes; populations and variations
  • biomechanics: muscles, levers, forces, strength
  •  environmental physics: noise, light, heat, cold, radiation, vibration body systems: hearing, vision, sensations
  • applied psychology: skill, learning, errors, differences
  • Social psychology: groups, communication, learning, behaviours.

Importance of ergonomics


Ergonomics can help to increase the health and wellbeing of office personnel. Effective ergonomic products and practices can increase productivity by reducing the time taken to complete daily tasks, as well as reducing instances of absenteeism due to work-related injury or illness.


Physical ergonomics


Physical ergonomics: The science of designing user interaction with equipment and workplaces to fit the user. Physical ergonomics is concerned with human anatomy, and some of the anthropometric, physiological and bio mechanical characteristics as they relate to physical activity. Physical ergonomic principles have been widely used in the design of both consumer and industrial products.

Physical ergonomics is important in the medical field, particularly to those diagnosed with physiological ailments or disorders such as arthritis (both chronic and temporary) or carpal tunnel syndrome. Pressure that is insignificant or imperceptible to those unaffected by these disorders may be very painful, or render a device unusable, for those who are. Many ergonomically designed products are also used or recommended to treat or prevent such disorders, and to treat pressure-related chronic pain.


One of the most prevalent types of work-related injuries is musculoskeletal disorder. Work-related musculoskeletal disorders (WRMDs) result in persistent pain, loss of functional capacity and work disability, but their initial diagnosis is difficult because they are mainly based on complaints of pain and other symptoms. The Occupational Safety and Health Administration (OSHA) has found substantial evidence that ergonomics programs can cut workers’ compensation costs, increase productivity and decrease employee turnover. Therefore, it is important to gather data to identify jobs or work conditions that are most problematic, using sources such as injury and illness logs, medical records, and job analyses.


Cognitive ergonomics


Cognitive ergonomics is concerned with mental processes, such as perception, memory, reasoning, and motor response, as they affect interactions among humans and other elements of a system. (Relevant topics include mental workload, decision-making, skilled performance, human reliability, work stress and training as these may relate to human-system and Human-Computer Interaction design.)


Organizational ergonomics


Organizational ergonomics is concerned with the optimization of socio-technical systems, including their organizational structures, policies, and processes. (Relevant topics include communication, crew resource management, work design, work systems, design of working times, teamwork, participatory design, community ergonomics, cooperative work, new work programs, virtual organizations, telework, and quality management.)


Benefits of a Workplace Ergonomics Process

Here are five of the proven benefits of a strong workplace ergonomics process:


1.Ergonomics reduces costs. By systematically reducing ergonomic risk factors, you can prevent costly MSDs. With approximately 1 out of every 3 in workers compensation costs attributed to MSDs, this represents an opportunity for significant cost savings.


2.Ergonomics improves productivity. The best ergonomic solutions will often improve productivity. By designing a job to allow for good posture, less exertion, fewer motions and better heights and reaches, the workstation becomes more efficient.


3.Ergonomics improves quality. Poor ergonomics leads to frustrated and fatigued workers that don’t do their best work. When the job task is too physically taxing on the worker, they may not perform their job like they were trained. For example, an employee might not fasten a screw tight enough due to a high force requirement which could create a product quality issue.


4.Ergonomics improves employee engagement. Employees notice when the company is putting forth their best efforts to ensure their health and safety. If an employee does not experience fatigue and discomfort during their workday, it can reduce turnover, decrease absenteeism, improve morale and increase employee involvement.


5. Ergonomics  creates  a  better  safety  culture. Ergonomics  shows  your  company’s commitment to safety and health as a core value. The cumulative effect of the previous four benefits of ergonomics is a stronger safety culture for your company. Healthy employees are your most valuable asset; creating and fostering the safety & health culture at your company will lead to better human performance for your organization.


An ergonomic hazard is a physical factor within the environment that harms the musculoskeletal system. Ergonomic hazards include themes such as repetitive movement, manual handling, workplace/job/task design, uncomfortable workstation height and poor body positioning.


Ergonomic injuries may be referred to as Repetitive Stress Injuries (RSIs), Repetitive Motion Injuries (RMIs), Musculoskeletal Disorders (MSDs), Cumulative Trauma Disorders (CTDs), or Cumulative Trauma Injuries (CTIs). OSHA and NIOSH typically use the term MSD or Musculoskeletal Disorder.


Comfort through ergonomics


Comfort is much more than a soft handle. Comfort is one of the greatest aspects of a design’s effectiveness. Comfort in the human-machine interface and the mental aspects of the product or service is a primary ergonomic design concern.


Comfort in the human-machine interface is usually noticed first. Physical comfort in how an item feels is pleasing to the user. The utility of an item is the only true measure of the  quality of its design. The job of any designer is to find innovative ways to increase the utility of a product. Physical comfort while using an item increases its utility. Making an item intuitive and comfortable to use will ensure its success in the marketplace. The mental aspect of comfort in the human-machine interface is found in feedback.




Efficiency is quite simply making something easier to do. Efficiency comes in many forms, however.

  • Reducing the strength required makes a process more physically efficient.
  • Reducing the number of steps in a task makes it quicker (i.e. efficient) to complete.
  • Reducing the number of parts makes repairs more efficient.
  • Reducing the amount of training needed, i.e. making it more intuitive, gives you a larger number of people who are qualified to perform the task. Imagine how inefficient trash disposal would be if teenage child wasn’t capable of taking out the garbage.

ERGONOMIC HAZARDS: Occur when the type of work, body positions and working conditions put strain on your body. They are the hardest to spot since you don’t always immediately notice the strain on your body or the harm that these hazards pose. Short term exposure may result in “sore muscles” the next day or in the days following exposure, but long-term exposure can result in serious long-term illnesses.


Ergonomic Hazards include:

  • Improperly adjusted workstations and
  • Chairs frequent lifting
  • Poor posture
  • Awkward movements, especially if
  • They are repetitive repeating the same movements over
  • Over having to use too much force
  • Especially if you have to do it frequently

Physical Assessment


With this foundation, the first step of an ergonomic assessment will be to understand the physical demands associated with each job in order to help to identify any potential risks or areas for improvement. This step can be completed by performing a facility tour and observation of each department.


The physical demands required will likely differ across job roles and industries. For example, employees who primarily work in an office environment may require adjustments to their work station while employees who work in production may require specific training or additional equipment to avoid exertion and fatigue.


Ergonomic standards for office environments require a monitor to be at eye level to avoid an arching back or neck, wrists must be able to lay comfortably when typing, shoulders should be relaxed and parallel from a sitting or standing position, and feet should be flat on the floor. Providing adjustable desks and chairs will allow employees to customize the appropriate height and position for working while seated or standing.


Employees who are required to complete physical labor may also benefit from adjustable control stations as well as carts or dollies to reduce the impact of lifting or carrying heavy materials. Exertion may be reduced by rotating physical duties and providing stretch breaks throughout the day. Employees should always be trained on proper form and range of motion in order to prevent exhaustion and injury.


2. Understanding Employees’ Injury History Alongside a physical audit of the workplace environment, it is important to review the history of injuries throughout the population. This step can be completed by accessing information collected through claims data as well as surveying employees directly. The occurrences identified can help educate and prioritize procedures and establish resources.


Understanding the Benefits of an Ergonomic Assessment


Among the benefits of conducting an ergonomic assessment, employers can expect to see a reduction in costs associated with workplace injuries as well as an improvement in the productivity of daily operations. By providing the appropriate tools and technique, employees will feel less taxed throughout the day, which can contribute to greater focus and quality of work. In addition, regular assessments will help to establish a safe and positive culture throughout the company crucial for maintaining employee satisfaction and retention overall.


For Lifting/Lowering WISHA Lifting   Calculator


Developed by the Washington State Department of Labor and Industries and based on NIOSH research related to the primary causes of back injuries. This lifting calculator can be used to perform ergonomic risk assessments on a wide variety of manual lifting and lowering tasks, and can be also used as a screening tool to identify lifting tasks which should be analyzed further using the more comprehensive NIOSH Lifting Equation.


NIOSH Lifting Equation


This is a tool frequently used by occupational health and safety professionals for a more comprehensive assessment (when compared to the WA State Lifting Calculator) of manual material handling risks associated with lifting and lowering tasks in the workplace. The primary product of the NIOSH equation is the Recommended Weight Limit (RWL), which defines the maximum acceptable weight (load) that nearly all healthy employees could lift over the course of an 8 hour shift without increasing the risk of musculoskeletal disorders (MSD) to the lower back.


For Pushing, Pulling and Carrying Snook Tables


The Snook Tables outline design goals for various lifting, lowering, pushing, pulling, and carrying tasks based on research by Dr. Stover Snook and Dr. Vincent Ciriello at the Liberty Mutual Research Institute for Safety. The tables provide weight/force values, for specific types of tasks that are deemed to be acceptable to a defined percentage of the population. This is done by comparing data for each of the specific manual handling tasks against the appropriate table.


For Upper Body Posture Rapid Upper Limb Assessment (RULA)


This diagnostic tool assesses biomechanical and postural load requirements of job tasks/demands on the neck, trunk and upper extremities. A single page form is used to evaluate required body posture, force, and repetition. Based on the evaluations, scores are entered for each body region in section A for the arm and wrist, and section B for the neck and trunk. After the data for each region is collected and scored, tables on the form are then used to compile the risk factor variables, generating a single score that represents the level of MSD risk.


For Entire Body Posture


Rapid  Entire  Body Assessment   (REBA)


This tool uses a systematic process to evaluate whole body postural MSD and ergonomic design risks associated with job tasks. A single page form is used to evaluate required body posture, forceful exertions, type of movement or action, repetition, and coupling. A score is assigned for each of the following body regions: wrists, forearms, elbows, shoulders, neck, trunk, back, legs and knees. After the data for each region is collected and scored, tables on the form are then used to compile the risk factor variables, generating a single score that represents the level of MSD risk.


For Vibration Hand-Arm   Vibration Calculator


Although NIOSH has not issued a directive related to HAV, the UK developed guidelines under the Control of Vibration at Work Regulations in 2005 using the 2002 EU Physical Agents (Vibration) Directive. This regulation established and introduced vibration exposure action and limit values. In these regulations, the action value was set at a vibration magnitude of 2.5 m/s² and the limit value to 5 m/s². Both values are A(8) values, meaning they are average vibration magnitude values over the course of a 8-hour workday. This regulation serves as a good guide to evaluate HAV exposure, and also offers suggestions with respect to reducing associated risks.


Basic anthropometric core list


1.1      Forward reach (to hand grip with subject standing upright against a wall)

1.2      Stature (vertical distance from floor to head vertex)

1.3      Eye height (from floor to inner eye corner)

1.4      Shoulder height (from floor to acromion)

1.5      Elbow height (from floor to radial depression of elbow)

1.6      Crotch height (from floor to pubic bone)

1.7      Finger tip height (from floor to grip axis of fist)

1.8      Shoulder breadth (biacromial diameter)

1.9      Hip breadth, standing (the maximum distance across hips)

2.1      Sitting height (from seat to head vertex)

2.2      Eye height, sitting (from seat to inner corner of the eye)

2.3      Shoulder height, sitting (from seat to acromion)

2.4      Elbow height, sitting (from seat to lowest point of bent elbow)

2.5      Knee height (from foot-rest to the upper surface of thigh)

2.6      Lower leg length (height of sitting surface)

2.7      Forearm-hand length (from back of bent elbow to grip axis)

2.8      Body depth, sitting (seat depth)

2.9      Buttock-knee length (from knee-cap to rearmost point of buttock)

2.10      Elbow to elbow breadth (distance between lateral surface of the elbows)

2.11      Hip breadth, sitting (seat breadth)

3.1      Index finger breadth, proximal (at the joint between medial and proximal phalanges)

3.2      Index finger breadth, distal (at the joint between distal and medial phalanges)

3.3      Index finger length

3.4      Hand length (from tip of middle finger to styloid)

3.5      Hand breadth (at metacarpals)

3.6      Wrist circumference

4.1      Foot breadth

4.2      Foot length

5.1      Heat circumference (at glabella)

5.2      Sagittal arc (from glabella to inion)

5.3      Head length (from glabella to opisthocranion)

5.4      Head breadth (maximum above the ear)

5.5      Bitragion arc (over the head between the ears)

6.1      Waist circumference (at the umbilicus)

6.2 Tibial height (from the floor to the highest point on the antero-medial margin of the glenoid of the tibia)

6.3      Cervical height sitting (to the tip of the spinous process of the 7th cervical vertebra).




A person’s posture at work—the mutual organization of the trunk, head and extremities—can be analysed and understood from several points of view. Postures aim at advancing the work; thus, they have a finality which influences their nature, their time relation and their cost (physiological or otherwise) to the person in question. There is a close interaction between the body’s physiological capacities and characteristics and the requirement of the work.


Musculoskeletal load is a necessary element in body functions and indispensable in well-being. From the standpoint of the design of the work, the question is to find the optimal balance between the necessary and the excessive.


Postures have interested researchers and practitioners for at least the following reasons:


1.  A posture is the source of musculoskeletal load. Except for relaxed standing, sitting and lying horizontally, muscles have to create forces to balance the posture and/or control movements. In classical heavy tasks, for example in the construction industry or in the manual handling of heavy materials, external forces, both dynamic and static, add to the internal forces in the body, sometimes creating high loads which may exceed the capacity of the tissues. Even in relaxed postures, when muscle work approaches zero, tendons and joints may be loaded and show signs of fatigue. A job with low apparent loading—an example being that of a microscopist—may become tedious and strenuous when it is carried out over a long period of time.

2.  Posture is closely related to balance and stability. In fact, posture is controlled by several neural reflexes where input from tactile sensations and visual cues from the surroundings play an important role. Some postures, like reaching objects from a distance, are inherently unstable. Loss of balance is a common immediate cause of work accidents. Some work tasks are performed in an environment where stability cannot always be guaranteed, for example, in the construction industry.

3. Posture is the basis of skilled movements and visual observation. Many tasks require fine, skilled hand movements and close observation of the object of the work. In such cases, posture becomes the platform of these actions. Attention is directed to the task, and the postural elements are enlisted to support the tasks: the posture becomes motionless, the mus-cular load increases and becomes more static. A French research group showed in their classical study that immobility and musculoskeletal load increased when the rate of work increased

4.  Posture is a source of information on the events taking place at work. Observing posture may be intentional or unconscious. Skilful supervisors and workers are known to use postural observations as indicators of the work process. Often, observing postural information is not conscious. For example, on an oil drilling derrick, postural cues have been used to communicate messages between team members during different phases of a task. This takes place under conditions where other means of communication are not possible.

Safety, Health and Working Postures


From a safety and health point of view, all the aspects of posture described above may be important. However, postures as a source of musculoskeletal illnesses such as low back diseases have attracted the most attention. Musculoskeletal problems related to repetitive work are also connected to postures.


Low back pain (LBP) is a generic term for various low back diseases. It has many causes and posture is one possible causal element. Epidemiological studies have shown that physically heavy work is conducive to LBP and that postures are one element in this process. There are several possible mechanisms which explain why certain postures may cause LBP. Forward bending postures increase the load on the spine and ligaments, which are especially vulnerable to loads in a twisted posture. External loads, especially dynamic ones, such as those imposed by jerks and slipping, may increase the loads on the back by a large factor.


From a safety and health standpoint, it is important to identify bad postures and other postural elements as part of the safety and health analysis of work in general.





Solving the ergonomics puzzle is difficult, but it can be done. Start by conducting effective and efficient ergonomic assessments, and make sure you’re using the right tool for the job.






Web links

  • http://www.ergonomics.org
  • https://www.thoughtco.com/what-is-ergonomics-1206379 https://medlineplus.gov/ergonomics.html
  • https://www.osha.gov/SLTC/ergonomics/identifyprobs.html
  • https://www.berner-safety.de/ergonomics_pleasant_working_conditions_en_400.html