Ergonomics is defined as the science of work. It improves quality of work, productivity and safety by fitting products, tasks, and environment to people. In simple terms, it is the science of adapting the environment to the needs of the worker.

The work setting is characterized by an interaction among the following parameters:

1、 A worker with attributes of size, strength, range of motion, intellect, education, expectations, and other physical and mental capacities. 
2、 A work setting comprising parts, tools, furniture, control/display panels and other physical objects. 
3、 A work environment created by climate, lighting, noise, vibration, and other atmospheric qualities. 

 
Work Risk Factors
The risk of injury increases as the physical demands of a task increase. When the physical demands of a task exceed the physiological capabilities of a worker, an injury is likely to occur.

Certain characteristics of the work setting have been associated with injury. These work characteristics are called risk factors and include:

Posture

In an industrialised society, there is a significant mismatch between people and the furniture in their working environment, especially when it is transforming into an information processing society in which more workers sit for long periods of time. This has resulted in increasing numbers of employees suffering from chronic back pain.

The most likely explanation is that we are sitting in the wrong way, thereby injuring our backs, necks and arms. Poor posture, however, is more than the wrong sitting positions that we have adopted, it is the position of the body while performing work activities. Awkward posture is associated with an increased risk for injury. It is generally considered that the more a joint deviates from the neutral (natural) position, the greater the risk of injury.

Work methods or workplace dimensions can create posture problems. Examples of poor practices include bending and twisting to pick up a box; bending the wrist to assemble a part; and kneeling in the storage bay of an airplane because of confined space while handling luggage.

Sitting

Culturally we all have been taught to sit upright. However, it is inadvisable to sit this way for long stretches of time, as it may cause stress to your lower back muscles. It is good practice to stretch and take a short walk every 45 minutes or so.

A seat that tilts forward encourages the natural posture of the curve of the spine. Opposing muscle groups are balanced and the lumbar curve is preserved, producing balanced seating in which the back is straight, the joint angles are open and the muscles are relaxed. This position provides greater mobility and relieves pressure on the lungs and stomach.

Force

This factor is determined by the effort that is needed for the task. In general, the greater the force needed, the more serious the injury suffered by internal body tissues as a result of the task. For example, lifting heavy weights may result in compression or protrusion of the spinal discs.

Static Exertion

This reflects the difficulty and danger of maintaining an abnormal posture over an extended length of time in order to complete a task. This occurs in situations such as when a picture frame has to be held up at an awkward angle for the drilling of attachment hooks to be completed. The more awkward the position and the longer it is held, the greater the risk of injury.

Gloves

Although gloves exist to protect workers from harm, they are not good in maintaining dexterity. If a worker is not used to working with gloves, he may use greater muscular exertion to achieve a certain grip, thus increasing the risk of injury. However, if workers have become accustomed to working with gloves, and if the gloves fit well, dexterity will not be compromised, and additional muscular strength will not be needed.

Repetition

Chronic repetitive injury of the wrist is common among typists. Repetitive motion has been associated with injury and worker discomfort. Generally, the greater the number of repetitions, the greater the risk of injury.

Recovery time

Workers should be given breaks from performance of repetitive or long-drawn activity. This allows strained body areas to rest. Short work pauses reduce perceived discomfort and rest periods between exertions have been shown to reduce incidences of repetitive strain injury.

Segmental vibration (Hand-Arm vibration)

Studies have shown that chronic vibration applied to the hand can cause a decrease in blood flow to the hands/fingers (Raynaud's disease or vibration white finger). Carpal tunnel syndrome and segmental vibration have also been linked in some studies.
It can also damage the sensory receptor feedback leading to increased handgrip force to hold the tool.

 
What can be done
Ergonomics seeks to improve worker health and efficiency through the design and engineering of the work environment, and also through the education and training of workers in healthy work practice. Thus ergonomic concerns are now a key factor in the design of working environment, and employees are encouraged to learn and apply good health practices in their workplace. With effort from all parties involved, workplace health and safety can be greatly improved.