Ergonomics and ergonomic problems in office work

Ergonomics is the science that studies how to adapt the relationship of the human being with his environment. It is a branch of Occupational Safety and Health that has developed a sub-discipline: office ergonomics, whose objective is to correct and design the work environment with a view to reducing the risks associated with this type of work (restricted mobility, inappropriate postures, poor lighting, noise, etc.) and its consequences on the worker's health and well-being (musculoskeletal injuries to the shoulders, neck, hand and wrists, circulatory problems, visual disturbances, etc.).

The purpose of this work is to know the status of some of the main ergonomic problems associated with office work, in ININ staff and some of its clients, as well as to provide all workers who carry out this work with the minimum necessary information to prevent and / or minimize the occupational risks to which they are subjected even when the appropriate furniture and ergonomic equipment are not available.

In the survey carried out on 100 office workers, it was known that 95% of the respondents lack the necessary ergonomic conditions in their jobs. The main perceived problems were:

Unfavorable conditions in chairs and work tables, poor location of computer equipment and prolonged stay in the same posture.

For each of them possible solutions are provided and information is also offered to office staff, to prevent and / or minimize a large part of the occupational risks to which they are subject and their consequences on their health and well-being.

Increasing importance is being given, worldwide, to activities aimed at guaranteeing safety and health at work. In this sense, our country intends to certify 124 to 131 Organizations with a Management System for Safety and Health at Work, covered by NC-18001: 20051 (which identifies the hazards, within which are ergonomic conditions to which the worker is subjected during the working day) and the right of workers to periodic monitoring of their health status, based on the occupational risks inherent in their job, guaranteed by Law 13 of Protection and Hygiene 2 and Decree 101 "General Regulations of the Work Protection and Hygiene Law" 3.

According to the official definition adopted, by the Council of the International Association of Ergonomics (IEA, 2000), Ergonomics is the science that studies how to adapt the relationship of the human being with his environment, hence it is applied to the design of products and equipment, mainly from the workplace to increase productivity by reducing fatigue, stress and discomfort4. For example, in the industry it is a matter of the machinery and tools have ergonomic handles with smooth and non-slip surfaces, to protect the worker and avoid accidents, as well as imposing pauses in works with repetitive movements or requiring great force5.

The human being was intelligently designed to be on the move during the day and to rest at night, even when we rest, hormones flow, blood circulates, and neurons send signals. However, civilization has increasingly "chained" us to chairs, first typewriters and now computers, people spend more time sitting than ever before in history, especially in offices and if we also adopt bad postures, poor skeleton, poor muscles, poor blood circulation!

For these reasons, Ergonomics as a branch of Occupational Safety and Health has developed a sub-discipline: office ergonomics, whose objective is to correct and design the work environment with a view to reducing the risks associated with this type of work (restricted mobility, inadequate postures, poor lighting, noise, etc.) and its consequences on the worker's health and well-being (musculoskeletal injuries to the shoulders, neck, hand and wrists, circulatory problems, visual disturbances, etc.).

Because of this, Organizations that manufacture office furniture and equipment are increasingly focused on providing a design that correctly reflects advances in this science.

The prevention of occupational risks in office work depends, to a large extent, on the equipment that is purchased complies with the minimum ergonomic quality requirements to reduce a good part of the postural discomforts so frequent in this work.

Every day the number of health professionals that alert and spread ergonomic considerations regarding office work increases6.

Sitting for so long is very damaging for several reasons: blood circulation, especially in the legs, where you should go and return, does not perform its task as effectively if there is no movement to help it. On the other hand, the spine, which should be kept straight, is often abused with the terrible habit of leaning towards the desk and, above all, towards the computer keyboard.

This, added to the stress, which tenses the muscles, ends up putting pressure on the vertebrae, causing discomfort at best, or causing displacement of those delicate bones that, together with the nerves, make up an intricate mechanism.

So comes back pain, and if you add to that the fact that the computer screen is not in front of the user, but to one side, the neck will suffer the consequences. Furthermore, the arms, often without support, must make an additional effort, which we are rarely aware of, to give the hands the strength to press the keys6.

The aforementioned brings as a consequence a series of pathologies such as severe spinal problems, carpal tunnel syndrome, neck and back pain, constant headaches, tendinitis and also discomfort in the shoulders, legs and other health-related problems.6

In addition, poor mobility in front of the work table, the inadequate position of the keyboard and ¨mouse¨, light, noise, air conditioning, the quality of the air that is breathed, difficulty in the use and management of computer programs and organization at work.

The concept of ergonomics incorporates another interesting aspect: that of guiding people to correct or learn to possess the best conditions in their workplace.

For all the above, to know the status of some of the ergonomic conditions with which the office workers of the Institute for Standardization Research (ININ) and some of its clients work, as well as, provide the minimum information necessary to prevent and / or minimize The occupational risks associated with this type of work are the fundamental objectives of this work.

M aterials and Methods

The desired dimension of the sample was defined using the formula proposed by the FDX 50-172 standard of 1999: Customer Satisfaction Survey: 7

where:

n Sample size.

Z a / 2 Value of the centered normal law reduced to the threshold a. (1.96)

a Confidence threshold. (95%)

Ps Proportion observed through a previous study.

E Desired accuracy. (5%)

As stated in said norm, a preliminary study was carried out which allowed estimating, with a 95% probability, 7% of workers with favorable ergonomic conditions in their jobs, (Ps) which establishes that the sample number that should be chosen according to the formula would be 100 (n = 100). These values were confirmed after the survey was carried out, recalculating the n with the value of the real Ps obtained.

A survey was carried out on some ergonomic aspects that cause occupational risks in office work to 100 ININ workers and some of its clients, in June 2006.

The format of the survey carried out appears in the Annex.

R esults and discussion

Of the 100 respondents, only 5 work in favorable ergonomic conditions. This confirms the estimate made since with the 5% satisfaction obtained the n = 72.96, which indicates that with 73 respondents it would have been sufficient.

The main problems perceived in the surveys are reflected in the table. As can be seen, a high percentage of workers have ergonomic difficulties with work tables and chairs, poor location of their computer equipment and prolonged stay in the same position.

All this causes bad postures that sustained prolonged periods produce static muscular efforts that can cause fatigue, musculoskeletal injuries to the shoulders, neck, back, hands and circulatory disorders such as numbness in the legs. The disorders in muscles and bones of the back and arms, which derive from bad postures in the workplace, is one of the most frequent occupational health problems worldwide8,9

Table: Percentage of the main problems detected

Perceived problems	Respondents (%)
Poor ergonomic conditions in the work chair.	92
<1.15 m free in front of your work table so that the chair can be easily moved.	87
They sit 6 or more hours a day	62
<55 cm between the eyes and the monitor screen.	51
<10cm between the keyboard and the edge of the table	48
Glare and reflections of light on the monitor screen.	47
They stand 5 or more hours a day.	42
Inadequate table height	38
Monitor Position	17
Difficulty handling the ¨Mouse¨	17

The following are possible solutions to the problems detected even when the appropriate furniture, equipment and accessories described in this work are not available:

The work chair:

They must have wheels and the possibility of turning to allow mobility and access to the work elements. (Figure 1) It must have rounded corners and no hard edges or edges. The front edge should be gently curved to avoid compressions below the thighs and knees. If your chair does not have these characteristics, the use of cushions will help to produce such effects. The padding of the seat and backrest should not be too fluffy since instead of holding and helping to maintain the correct position of the spine, they adopt all deformations without correcting any. It must be remembered that everything soft is bad for the back. The ideal is a firm filling of 2 or 3 cm. thick on a hard base 4.The optimum depth of the seat will be that which allows the backrest to be used without excessive pressure being felt below the knees. They must have adequate lumbar support, if they do not have it, use a small cushion in the backrest that adjusts according to the height of the seat. user.The height of the backrest must reach at least the middle of the back (below the shoulder blades).It must have armrests (slightly behind the edge of the seat to allow you to approach the table comfortably), to give support and Rest on the shoulders, arms and relieve muscle tension in both. The height of the chair should be adjustable10 to adapt it to the table (so that it is at the elbows), and if necessary, request a footrest.if you do not have it, use a small cushion in the backrest that adjusts according to the height of the user. The height of the backrest must reach at least the middle of the back (below the shoulder blades). It must have armrests (somewhat delayed compared to on the edge of the seat to allow you to approach the table comfortably), to give support and rest to your shoulders, arms and relieve muscle tension in both. The height of the chair must be adjustable10 to adapt it to the table (so that it at the elbows), and if necessary request a footrest.if you do not have it, use a small cushion in the backrest that adjusts according to the height of the user. The height of the backrest must reach at least the middle of the back (below the shoulder blades). It must have armrests (somewhat delayed compared to on the edge of the seat to allow you to approach the table comfortably), to give support and rest to your shoulders, arms and relieve muscle tension in both. The height of the chair must be adjustable10 to adapt it to the table (so that it at the elbows), and if necessary request a footrest.to give support and rest to the shoulders, arms and relieve muscle tension in both. The height of the chair must be adjustable10 to adapt it to the table (so that it is at the elbows), and if necessary request a footrest.to give support and rest to the shoulders, arms and relieve muscle tension in both. The height of the chair must be adjustable10 to adapt it to the table (so that it is at the elbows), and if necessary request a footrest.

The recommended dimensions of the footrest are 33 cm deep, with a width of at least 45 cm and an inclination between 10 and 25 degrees. The support surface must be non-slip, as well as its base, to prevent it from ending up at the bottom of the table.

If you do not have a suitable footrest, a piece of wood, to which a type of rubber is attached or any non-slip material can solve the problem. If the height of the chair cannot be adjusted, use cushions or lower the height of its supports to the floor.

Executive chairs have worse ergonomic performance than office chairs. Before ordering a manager's seat, reflect on the type of tasks you actually perform and the importance of representation aspects or certain aesthetic and material attributes (leather, high back, etc.) for your work. Do not change ergonomic quality for appearances.

The working table:

It should be approximately at the elbow height when sitting (72 ± 1.5 cm, up to 75 ± 1.5 cm for very tall users). If the table is greater than 76 cm, it is necessary to apply a lower one or reduce the height of its supports to the floor. (Figure 2) It must be large enough to allow flexible placement of the monitor, keyboard, documents and accessories, so that the operator can maintain an adequate visual distance from the screen. 180 × 80 cm is recommended; there should be a loose space under the work table so that the legs can move. It is recommended that the free height reaches 70 cm and that the free width exceeds 85 cm. You must have a lectern to place the documents. If there is no lectern, at least,documents should be arranged in such a way that uncomfortable movements of the head and eyes are minimized. The table surface should be poorly reflective (matte finishes, shiny ones may reflect). In general, soft colors are preferable and very dark surfaces, which produce very strong contrasts between the tabletop and documents, should be avoided. The surfaces in gray, beige, cream or natural wood color, more or less clear, provide adequate contrasts. It must have its perimeter free to take advantage of the work surface and allow the worker mobility. The drawer blocks must not be fixed to table,since this way the worker will be able to place them in the area that is most convenient for him and will make the best use of the work surface and they must have opening stops so that they do not all come out when opening them, if they do not have them, small dowels should be placed for such purposes Wood.It is advisable that the work tables are electrified, to avoid the use of extensions that can lead to accidents and constitute a hindrance. Never use burglar-type connections to connect several pieces of equipment to the same socket: not only are they ungrounded (with the corresponding risk of electrical contact), they can become hot and even pose a risk of fire if devices with a certain power are connected. If your table is not electrified, you can use a connection box suitable for the power to be used and always with a ground connection.Never replace the plug of an original cable with one without an earth connection.

Sitting position

In the sitting posture the weight of the body is distributed between the seat and the floor; about 16% of the total weight weighs on it. Due to the massive use of computers we remain seated, more than ever before in history, so the following precautions must be taken:

The feet must be completely supported on the ground, if it is not reached, a footrest must be used. The height of the seat should be adjusted so that it transfers the body weight through the buttocks and not the thighs. remain upright, with the shoulders back and the spine straight, (so that the intervertebral discs can correctly distribute the weight and avoid deformation of the spine11), with support of the lumbar area to the back of the chair and not allowing the body to bend forward arching your back. If lumbar support is not available, a wedge-shaped cushion located on the back helps maintain proper posture.8

Standing position

The worker should avoid long periods of standing time. The activity of the leg muscles acts as a valve and helps the veins return blood to the heart. If the same position is maintained for a long time, this action is reduced, causing swelling of the lower extremities10. However, if it is necessary to maintain this position, it is recommended, to reduce excessive curvature in the back and discomfort in the lumbar area, slightly raise one foot alternating it from time to time (Figure 3).

In addition, seats must be provided that can be used during rest breaks.12

Work space:

The workplace must be of a sufficient size and conditioned in such a way that it allows movements and favors changes of posture. (Figure 4). Behind the table there should be a space of approximately 115 cm or more to move with the chair and facilitate movements and posture changes. Restricted mobility causes musculoskeletal problems.

Glare and reflections of light on the monitor screen.

Light sources should be positioned so as to avoid glare and nuisance reflections on the screen or other parts of the equipment. Work stations should be installed in such a way that natural light sources such as windows and other openings, transparent partitions or Translucent and light colored equipment or partitions are parallel to the screen, neither in front nor behind to avoid direct glare and the production of annoying reflections on the screen. Never, because you run away from reflections, place the computer in an incorrect position that forces you to work with torsion of the trunk and / or neck. (Figure 5) Windows and openings must be equipped with blinds or curtains to reduce daylight that illuminates the workplace.Screen filters should be used to decrease or cancel light reflection and radiation emissions. Reflections produce a greater effort of vision.

Monitor position:

The height of the monitor should be such that its upper edge is at the level of the user's eyes with the head raised9 13 (approximately 43 to 47 cm above the plane of the table). If the monitor is not on an adjustable stand and is too low, place a firm stand underneath to raise it. The distance from the screen to the eyes, as a general rule, should not be less than 55 cm (Figure 6). Staying for a long period of time in front of the monitor will lead to visual discomfort, burning, itching, headaches, etc. A good habit is to take your eyes off the monitor every half hour and blink to moisten it. You should work with your head facing the computer, avoiding gyrations. The maximum turning angle of the head should be less than 35 degrees.

Keyboard position and ¨mouse¨:

The keyboard should be tiltable and independent of the screen, preventing fatigue and discomfort in the arms. The keyboard should not be too high. As a general rule, the central part of the keyboard (row A) should be less than 3 cm above the table. If not, there should be pads that raise the point of support of the wrists (wrist rests) and forearms. Fully supporting both wrists is highly recommended, especially when the work chair lacks armrests. There must be a sufficient space between the keyboard and the edge of the table (10 cm minimum), in order to support the wrists and forearms on the table (Figure 7). The wrists should be in a natural and straight position on the keyboard. Avoid bending or placing your wrists at angles.When typing on the keyboard, the hands must be kept relaxed, avoiding the stiffness of the fingers. The ¨mouse¨ must have a shape that allows it to be used comfortably by both right and left handed people. Left-handers should position the mouse to the left and change the key settings in the configuration menu, although you must learn to use the "mouse" with both hands to avoid overloading the work of a single arm. In three weeks, the habit is acquired. The ¨mouse¨ should be positioned in such a way that it can be handled easily, without twisting or extending the arm.although you must learn to use the "mouse" with both hands to avoid reloading the work of a single arm. In three weeks, the habit is acquired. The ¨mouse¨ should be positioned in such a way that it can be handled easily, without twisting or extending the arm.although you must learn to use the "mouse" with both hands to avoid reloading the work of a single arm. In three weeks, the habit is acquired. The ¨mouse¨ should be placed in such a way that it can be easily handled, without twisting or extending the arm.

Figure 8 shows some of the bad postures adopted (8A) and their corrections (8B)

Conclusions

95% of the surveyed workers have unfavorable ergonomic conditions in their jobs.The main problems detected were: the lack of ergonomic conditions in chairs and work tables, poor location of computer equipment and prolonged stay in the same posture. It provided possible solutions to the problems detected and the minimum information necessary to prevent, as far as possible, the main occupational risks caused by office work, even in the absence of the ergonomic furniture and equipment recommended in this work.

Bibliography

1. Cuban Standard 18001 (2005) Safety and Health at Work- Management System for Safety and Health at Work. Requirements

2. Law 13 (1977) on Protection and Hygiene at Work

3. Decree 101 (1982). General Regulations of the Work Protection and Hygiene Law.

4. Office ills

. Www.paritarios.cl/especial_los_males_dela_oficina.htm 5. Repeated movements and bad postures. www.inp.cl/inicio/enferm_rec_datep.php.

6. Bad Postures on the Computer.www.monographies.com / 13 / bad / bad.shtml

7. FDX Standard 50-172 (1999). Quality Management and Quality Assurance. Customer satisfaction survey

8. A healthy job www.economíaynegocios.cl / tus_finanzas.asp

9. Guide for the prevention of occupational risks in offices

10. NC 19-02-32. System of Standards of Protection and Hygiene at Work. Seats for the working media. Classification and General Requirements.

11. Correct posture at work www.paritarios.cl/consejos correct postures. html