Although defined in 1963 as “the fitting of the task to the man”, ergonomics developed as a coordinated subject during World War II. This involved scientists, engineers, psychologists, physiologists and doctors working together to consider the effects of work-related tasks on people
‘How humans interact physically and psychologically within the work environment’.
In a work-related context, once production is underway, success can only be guaranteed if managers, supervisors and operators are aware of ergonomics in addition to their equipment and tasks. Safer equipment and a safe place of work alone cannot secure safe standards for employees.
The key issues in relation to ergonomics are:
- The role of ergonomics in job design
- The influence of equipment design on human reliability
- The influence of process design on human reliability
- The employee and work station as a system
- Elementary physiology (human anatomy)
- Anthropometry (body measurements)
- The degradation of human performance resulting from poorly designed work stations
- Ergonomically designed control systems
The term ergonomics can be defined in a number of ways:
The scientific study of the interrelationships between people and their work.
The study of the relationship between man, the equipment with which he works and the physical environment in which this “man-machine system” operates.
The study of ergonomics, which means “fitting the task to the individual”, involves a number of disciplines, including psychology, anatomy, physiology, occupational health, and various areas of engineering.
Furthermore, this man/machine interface is significant in the design of work layouts, displays and controls on the machinery and equipment, safe systems of work and in setting of work rates.
The ergonomic approach to Health and Safety examines, in particular, the physical and mental capacities and limitations of operators. Taking into account, at the same time, psychological factors, such as learning, individual skills, perception, attitudes, vigilance, information processing and memory, and physical factors, such as strength, stamina and body dimensions. It is also concerned with the working environment and the potential for environmental stress associated with, for instance, extremes of temperature, inadequate lighting, noise and vibration.
Ergonomics, therefore, is a very broad area of study largely concerned with maximizing human performance and, at the same time, eliminating as far as possible, the potential for human error.
The main goals of ergonomics are to reduce errors and increase production. To enhance safety and comfort when the human interacts with a system, improving information-processing capabilities of the brain.
There are a number of principles which those are involved in solving ergonomic problems in the workplace.
Principle 1: Work in Neutral Postures
Your posture provides a good starting point for evaluating the tasks that you do. The best positions in which to work are those that keep the body “in neutral”.
Maintain the “S-curve” of the spine
It is important to maintain the natural S-curve of the back, whether sitting or standing. The most important part of this “S” is in the lower back, which means that is good to keep a slight “sway back”.
When standing, putting one foot up on a footrest helps to keep the spinal column in proper alignment.
Keep the neck aligned
The neck bones are part of the spinal column and thus are subject to the same requirements of maintaining the S-curve. Prolonged twisted and bent postures of the neck can be as stressful as its equivalent for the lower back.
The best way to make changes is usually to adjust equipment so that your neck is in its neutral posture.
Principle 2: Reduce Excessive Force
Excessive force on your joints can create a potential for fatigue and injury. In practical terms, the action item is for you to identify specific instances of excessive force and think of ways to make improvements.
For example, pulling a heavy cart might create excessive force for your back. To make improvements, it might help to make sure the floor is in good repair, that the wheels on the cart are sufficiently large, and that there are good grips on the cart. Or a power tugger might be needed.
Another kind of example is having handholds on boxes or carrying totes. Having the handhold reduces the exertion your hands need to carry the same amount of weight.
Principle 3: Keep Everything in Easy Reach
The next principle deals with keeping things within easy reach. In many ways, this principle is redundant with posture, but it helps to evaluate a task from this specific perspective.
Reach Envelope
One concept is to think about the “reach envelope.” This is the semi-circle that your arms make as you reach out. Things that you use frequently should ideally be within the reach envelope of your full arm. Things that you use extremely frequently should be within the reach envelope of your forearms.
Principle 4: Work at Proper Heights
Do most work at elbow height
A good rule of thumb is that most work should be done at about elbow height, whether sitting or standing.
A real common example is working with a computer keyboard. But, there are many other types of tasks where the rule applies.
Exceptions to the Rule
There are exceptions to this rule, however. Heavier work is often best done lower than elbow height. Precision work or visually intense work is often best done at heights above the elbow.
Principle 5: Reduce Excessive Motions
The next principle to think about is the number of motions you make throughout a day, whether with your fingers, your wrists, your arms, or your back.
One of the simplest ways to reduce manual repetitions is to use power tools whenever possible.
Another approach is to change layouts of equipment to eliminate motions. In the example here, the box is moved closer and tilted, so that you can slide the products in, rather than having to pick them up each time.
Principle 6: Minimize Fatigue and Static Load
Holding the same position for a period of time is known as static load. It creates fatigue and discomfort and can interfere with work.
A good example of static load that everyone has experienced is writer’s cramp. You do not need to hold onto a pencil very hard, just for long periods. Your muscles tire after a time and begin to hurt.
In the workplace, having to hold parts and tools continually is an example of static load. In this case, using a fixture eliminates the need to hold onto the part.
Principle 7: Minimize Pressure Points
Another thing to watch out for is excessive pressure points, sometimes called “contact stress.”
A good example of this is squeezing hard onto a tool, like a pair of pliers. Adding a cushioned grip and contouring the handles to fit your hand makes this problem better.
Principle 8: Provide Clearance
Having enough clearance is a concept that is easy to relate to.
Principle 9: Move, Exercise, and Stretch
To be healthy, the human body needs to be exercised and stretched.
You should not conclude after reading all the preceding information about reducing repetition, force, and awkward postures, that you’re best off just lying around pushing buttons. Muscles need to be loaded, and your heart rate needs periodic elevation.
Watch our latest Take Five Minutes for H&S YouTube Video Take Five for Ergonomic Principles. If you need help understanding ergonomics and work and the effect posture, workload and types of work can have on it, then speak to our team at Cambridge Safety today.
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