2011 The Basics of Ergonomics
“…the study of the relationship between workers and their environment, esp. the equipment they use.”
Rob Vajko 2/21/2011
www.nationalsafetyinc.com
The Basics of Ergonomics What is “Ergonomics”? Dictionary.com defines ergonomics as… “the study of the relationship between workers and their environment, esp. the equipment they use.” While this is technically a correct definition, ergonomics as most of us understand it goes beyond this. It is essentially the science of “fitting” people and the environment (whether work or recreation) together in such a manner as to keep people from muscular, nervous system or skeletal harm, discomfort or fatigue.
Understanding the extent of the problem According to ergoweb.com overexertion injuries account for 25.7% of injury related costs to businesses. Additionally, bodily reaction injuries (defines as the “type of injury [that] occurs when a worker a tries to regain a loss of balance during bending, climbing, and slipping or tripping without falling.”) account for another 10% of that cost. Back injuries account for most of these injuries. Studies about the effectiveness of back supports have raged for a while but continued studies are slowly showing the undeniable effectiveness of properly worn back supports. Ergonomics encompass the following: 1. Repetitive Strain Injuries (RSI) RSI (also known as Cumulative Trauma Disorder) includes all injuries resulting from continuous, repetitive tasks that strain, stretch or compress the muscles, nerves or tenons. Symptoms of RSI include the following: o Tingling, numbness and/or loss of sensitivity in the hands o Loss of strength in the hands that results in clumsiness and/or coordination o Pain, soreness or aching of the muscles in the hands, wrists, arms or fingers o Upper back, neck and/or shoulder pain Preventing RSI • RSI is usually a result of poor posture or bending and stretching in such a manner as to compress or stretch soft tissue. Proper posture is the first line of defense against RSI. In typing at the computer, for example, make sure that wrists are straight and level. Avoid bending or stretching wrists or fingers excessively or repeatedly. Do not rest your wrists on the desktop or on the computer keyboard.
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www.nationalsafetyinc.com • • • • • • •
Avoid anything that feels strained or awkward. Type loosely and hold the mouse gently. As much as possible, avoid using the mouse altogether by learning as many of the keyboard shortcuts as possible. Additionally, take time to stretch and shift positions regularly and frequently in order to change up the way the soft tissue, muscles and tenons are being used. “Shake out” your hands and arms occasionally to promote better circulation and to loosen up the muscles. Take time out for breaks to relax and allow hands and arms to rest. Take note of shoulder, neck or upper back pain as this is where problems often show up first. Pay attention to frequent headaches as well. They could be a symptom of poor posture.
2. Vibration and impact related injuries Continuous, repeated vibrations to the hands and wrists (though by no means limited to these) can result in vibration white finger (VWF), also known as hand‐arm vibration syndrome (HAVS). Vibrations in the 5‐150 Hz are the most dangerous and responsible for most of the cases of VWF. Symptoms: • • •
Tingling or numbness at the end of the work shift. Color changes – White or pale fingers are usually the first symptom but this is usually followed by redness or a bluish color as the blood returns to the fingers. Loss of dexterity as fingers are weakened and muscles start to become damaged.
Preventing VWF: • • • • • • •
Look first of all for alternate ways of doing the job that do not require constant vibration being transferred to the fingers If vibration tools must be used, look for tools that have a higher or lower frequency range. Use anti‐vibration gloves Use tool wraps Reduce the vibrations to the fingers by holding the tool loosely Take frequent breaks (at least 10 minutes for every hour of work) Keep your hands warm. Cold hands have a slower blood flow which accelerates and aggravates that problem.
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www.nationalsafetyinc.com A quick image search on the web will show you why you want to take this issue seriously. The end result of untreated white finger is the same as severe frostbite, so if you need to use vibrating tools, learn to protect against VWF. 3. Carpal Tunnel Syndrome (CTS) CTS is related to RSI resulting in swollen tendons, usually in the hand and arms. It is a result of pressure on the median nerve in the wrist, the nerve that provides movement and feeling to the hand. It is most often associated with typing but can also result from any task that require the hands or wrists to perform repetitive motions such as assembly line work. Symptoms of CTS: • • • • •
Numbness in the hand, wrist or fingers An ache or sharp pain in the wrist and/or hand Tingling, as if the hand had “fallen asleep” Loss of strength and/or control Weakness in the hand
Prevention and treatment of CTS: • • • • •
Get ergonomic equipment (ergonomic keyboards, wrist pads, ergonomic mouse, etc…) Raise or lower equipment so as to reduce stress on the median nerve. Wear a wrist brace to keep the wrist from overflexing the wrist and/or hands Take frequent breaks and “shake out” the hands, arms and wrists A change of duties may be necessary in order to give the arms, wrists and hands a rest and a chance to heal
If the initial symptoms are ignored, the condition can slowly get worse to the point where surgery may be required. In some cases, the damage can become irreversible and the damage permanent.
4. Cognitive Ergonomics Cognitive ergonomics (CE) is a more recent and emergent form of ergonomics that seeks to understand how our environment affects the way we think and feel. It attempts to measure the effects of the work environment on mental processes such as perception, memory and motor skills; A work environment that is designed to maximize the manner in which workers react or respond to it will result in a work environment where fewer accidents happen. A good example might be the design of a piece of machinery that a worker would need to operate. The size and color of the buttons that the user is going to need to push, the size of the dials, the placement of the buttons and dials, the accessibility of visual displays… all of these will affect the way the user interacts with the piece of machinery. If done well, the user feels
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www.nationalsafetyinc.com more comfortable using the machine, he is more confident and, because of this, he is able to operate the machine safely and his productivity is increased. If, on the other hand the dials and knobs and displays are too big, too small, badly placed, etc… the user is going to struggle more, feel more frustrated at his job, feel less confident and might make more errors, perhaps even causing injuries to himself and others and decreasing productivity. While CE is most often associated with the fields of engineering (those who are going to decide the size of the knobs, the colors of the dials and the positions of the displays) there are also implications for workers and supervisors as well. A basic understanding of the way in which we respond to our environment, the way we feel when that interaction is strained or difficult, the way in which things just seem to flow when that interaction is smooth and natural, can and will determine how we set up our work area, how we layout our tools and much more. Finding ways to reduce the mental stress associated with poorly designed work areas, messy workstations, etc… are going to promote better health in the employees and increase productivity. After all, a happy employee is going to do a lot better work than a stressed, frustrated one.
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