The main reason for occurrence of musculoskeletal disorders (MSDs) is due to exposure to ergonomics risk factors. The exposure to more than one risk factor usually leads to musculoskeletal injuries to workers. Duration of exposure plays significant role for the injuries.
(a) Repetition
Performing a task or a series of repeated identical motions over and over again with little variation could cause overuse of muscle groups and tendons in the same way which could lead to muscle fatigue. With job variation which involves different muscle groups, muscle groups have periods of rest and this may reduce the rate of injury. Common examples of repetition are excessive clicking of the mouse, typing, stapling, keyboard operation, packing, palletising, depalletising, toll operating and others.
(b) Force
Force is the mechanical or physical effort to perform a task, for example, performing manual handling activities such as pushing or pulling the trolley, palletising, manipulating loads without any support and others. Excessive force means higher mechanical load to the muscles, ligaments, tendons and joints. Exerting high forces can cause fatigue and physical damage to the body, where the effects may be acute or chronic. The more force required to perform a particular task or the longer the force must be applied, the greater the risk of MSDs occurring.
(c) Posture
Posture is the position of a part of the body or the arrangement of the limbs. Awkward posture or poor posture refers to positions of the body that deviate significantly from the neutral position while performing tasks. Examples such as overreaching, bending and twisting will increase the strain to muscles, tendons and increase the force and muscular efforts.
(d) Contact Stress
Contact stress is caused by any sharp or hard object putting localised pressure on a part of the body . Contact stress will irritate local tissues and interfere with circulation and nerve function.
(f) Production Pressure
Production pressure will lead to occupational stress. Once a person is exposed to stress, it will directly affect his emotions. Once a person's emotional state is not balanced, it will reduce the person's awareness of work process and affect the production, quality, safety and others. Besides
that, stress aggravates musculoskeletal disorders.
(g) Environment
Environmental elements which can affect humans are as follows:
(i) Vibration
Vibration can be categorised as whole-body vibration and hand-arm vibration.
Whole-body vibration (WBV) is transmitted through the seat or feet of employees who drive mobile machines, or other work vehicles, over rough and uneven surfaces as a main part of their job. Whole-body vibration from driving puts stress on the spinal tissues and can contribute to lower back pain and fatigue.
(ii) Extreme Temperature
Environmental conditions such as extreme heat or cold can place stress on tissues. Extreme cold constricts blood vessels and reduces sensitivity and coordination of body parts. Excessive heat can result in increased fatigue and heat stress.
(iii) Noise
Annoying noises can make workers stressed and could affect their performance in terms of quality, productivity and safety.
(iv) Lighting
The conditions of indoor lighting are based on the task that is being performed. One of the best resources for indoor lighting is ISO 89951:2002 Lighting of work places Part 1: Indoor. Poor lighting can cause eye strain and can sometimes lead to awkward posture.
(a) Repetition
Performing a task or a series of repeated identical motions over and over again with little variation could cause overuse of muscle groups and tendons in the same way which could lead to muscle fatigue. With job variation which involves different muscle groups, muscle groups have periods of rest and this may reduce the rate of injury. Common examples of repetition are excessive clicking of the mouse, typing, stapling, keyboard operation, packing, palletising, depalletising, toll operating and others.
(b) Force
Force is the mechanical or physical effort to perform a task, for example, performing manual handling activities such as pushing or pulling the trolley, palletising, manipulating loads without any support and others. Excessive force means higher mechanical load to the muscles, ligaments, tendons and joints. Exerting high forces can cause fatigue and physical damage to the body, where the effects may be acute or chronic. The more force required to perform a particular task or the longer the force must be applied, the greater the risk of MSDs occurring.
(c) Posture
Posture is the position of a part of the body or the arrangement of the limbs. Awkward posture or poor posture refers to positions of the body that deviate significantly from the neutral position while performing tasks. Examples such as overreaching, bending and twisting will increase the strain to muscles, tendons and increase the force and muscular efforts.
(d) Contact Stress
Contact stress is caused by any sharp or hard object putting localised pressure on a part of the body . Contact stress will irritate local tissues and interfere with circulation and nerve function.
(f) Production Pressure
Production pressure will lead to occupational stress. Once a person is exposed to stress, it will directly affect his emotions. Once a person's emotional state is not balanced, it will reduce the person's awareness of work process and affect the production, quality, safety and others. Besides
that, stress aggravates musculoskeletal disorders.
(g) Environment
Environmental elements which can affect humans are as follows:
(i) Vibration
Vibration can be categorised as whole-body vibration and hand-arm vibration.
Exposure to hand-arm vibration can occur while using power tools and is a cause of significant ill health. Vibration from power tools can place stress on the tissues of the fingers, hand and arms. Tools that are not properly maintained or are inappropriate for the task may increase the amount of hand-arm vibration. These exposures may result in fatigue, pain, numbness, tingling, increased sensitivity to cold and decreased sensitivity to touch in the fingers, hands and arms (hand-arm vibration syndrome).
Whole-body vibration (WBV) is transmitted through the seat or feet of employees who drive mobile machines, or other work vehicles, over rough and uneven surfaces as a main part of their job. Whole-body vibration from driving puts stress on the spinal tissues and can contribute to lower back pain and fatigue.
(ii) Extreme Temperature
Environmental conditions such as extreme heat or cold can place stress on tissues. Extreme cold constricts blood vessels and reduces sensitivity and coordination of body parts. Excessive heat can result in increased fatigue and heat stress.
(iii) Noise
Annoying noises can make workers stressed and could affect their performance in terms of quality, productivity and safety.
(iv) Lighting
The conditions of indoor lighting are based on the task that is being performed. One of the best resources for indoor lighting is ISO 89951:2002 Lighting of work places Part 1: Indoor. Poor lighting can cause eye strain and can sometimes lead to awkward posture.
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