Occupational safety and health management shall carry out a study on workstations before making any modifications…
If you as a reader see this title for the first time, surely what comes to your mind is the introduction to a mystery novel or a horror movie in the best Hollywood style; but no, it is not what you think.
The mysterious chair is the title that occurs to us to express a concern that we have collected throughout these years in which we have been learning as well as teaching about health and safety at work.
In this sense, the concern has been raised throughout the workshops given on Ergonomics and Working Conditions. Generally after the introduction of rigor and the presentation of the workshop, the following question is usually asked: "According to your knowledge, what is ergonomics?"
Based on this question, the answers that are generally obtained from the participants are as follows: 40% do not answer, 30% give us "more words, less words" the definition that appears in the Organic Law of Prevention, Conditions and Environment of Work (LOPCYMAT), 20% tells us that it is a discipline in charge of the comfort of the job, 6% responds sharply "I have no idea" and only 4% responds, that "it is the discipline in charge of adapting the environment to the people ”.
Of those responses obtained, the one that most closely approximates the reality of the definition and application of Ergonomics is the last one, and if we observe carefully we will realize that it is the one with the lowest percentage of knowledge. It is here where the restlessness begins to be generated. If we look for a slightly more formal definition of the concept of Ergonomics, we can refer to that given by Melo (2009), which tells us that:
Ergonomics is the adaptation of the environment to man, leaving aside the typecasting of the concept in the workplace. Ergonomics applies to the entire environment of people, whether in the workplace, at home, in transport, in sports, etc. When referring specifically to the area of work, Ergonomics is usually defined as the humanization of work and work comfort.
Taking what has been said previously, we can say that ergonomics is applied to everything that surrounds man, from a simple chair, through parts assembly stations within an industry, to the most advanced control system, such as that of a nuclear power generation station.
On the other hand, if we take the concept of adaptation of the environment to people, specifically to work, we must focus on ensuring that the human capital that works within an organization performs its tasks in such a way that it does not present accidents or occupational diseases Throughout his professional life, the following aspects should be emphasized from the point of view of ergonomics:
• The machines, furniture, equipment and tools that will be used to carry out the tasks inherent to the position.
• The specific area where the activity will take place.
• Environmental aspects that directly affect people such as noise, vibrations, cold, heat and lighting.
• How the work is made up: times, schedules, demand for attention to the task performed, among others.
From all these aspects we will focus on the furniture that is used to carry out work activities, specifically speaking of work chairs. In relation to the above, we can broaden our concern a little more, because the popular belief of people who perform tasks in a sitting position such as administrative tasks in general is "everything hurts, everything bothers me." This is evident when asked : Have you had a backache while executing your daily tasks at work? o Do you have any back pain or discomfort at the end of your working day? a high percentage answers affirmatively.
Hence, the million dollar question appears, "What do you think is the reason why you are presenting this type of inconvenience?", And here comes the million dollar winning answer, "LA SILLA".
If we analyze this answer carefully, we will find comments such as:
• It is very uncomfortable
• The padding is old
• Everything sounds familiar
• It's ugly
• It is not the most modern
• "It is not ERGONOMIC"
Among many other responses that you as a reader can imagine, but the focal point of these comments must generally be based on valid technical foundations, that is, a serious analysis of the situation must be carried out to determine what are the real causes of the presence of ailments in general. Thus, many of these "discomforts", without taking the responsibility off the chair, can be associated with multifactorial causes, such as an incorrect sitting posture to perform a certain task, a poor adjustment in the height of the chair, supporting, among others.
In this sense, we must bear in mind that being in a sitting position exerts an approximate 30 kg of additional pressure on the lumbar region, taking as a reference a person weighing 70 kilos than being in a standing position. Now if we add a bad posture when we sit down, the situation worsens. For example, if we sit with a stooped posture, we are not supporting the lower back, additionally, when assuming this posture, we sink the shoulders which tightens the muscles of the neck and the upper back.
On the other hand, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), there are other causes that can cause pain in the back and that are not necessarily related to the chair, such as:
Scoliosis, Spondylolisthesis, Arthritis, Lumbar Stenosis, Pregnancy, Kidney Stone, Endometriosis, Fibromyalgia, Infections, tumors and stress could also cause back pain.
If we take the previous information as a basis, we must recommend that, if you are presenting any discomfort in your back, do not rule out any possibility before blaming the chair for all its ills. Prevention through a periodic medical evaluation, a review of the conditions of the furniture in our workplace, receiving adequate and recurrent training in postural hygiene as well as a good routine of work breaks are factors that we must keep in mind to maintain our quality of life and thus preserve our health when executing our daily tasks.
For this reason, we are going to make a series of recommendations that you must have when choosing and using a chair to perform a certain task.
Factors of work chairs that we must take into account
I. Seat Height: The seat should be at a height that allows its user to comfortably rest their feet on the floor. Based on this, it is recommended that the chairs have height adjustable mechanisms for the seat.
II. Backrest: It is recommended that the height of the chair does not exceed the subscapular height, in turn it must allow accommodating the coccyx without pressing it. On the other hand, it is recommended that the height of the backrest, like that of the chair, be adjustable to accommodate the natural curvature of the spine.
III. Armrests: The main function of the armrests is to serve as a rest for the arms. Another important function is that it serves as a support to get up and sit, and allows us to adjust our body to different postures depending on the task that is being performed.
IV. Padding: The support of the chair must be fixed and stable, which must allow the impact to be absorbed when sitting and that it is not transmitted to the vertebrae of the spine. In this same sense it is recommended that the material that covers the seat and the backrest must allow the skin to breathe.
V. Base: It is recommended that it has self-locking wheels and that the chair has at least 5 support points to improve its stability.
Basics of selection of work chairs
Elements to Consider by the Management of Occupational Health and Safety
We have observed in most of the stations and work stations evaluated, that the majority of the work chairs do not adjust to the task performed, and even less to the anthropometric measurements of the people who use them.
In this same sense, we have even found people who assure that "the most expensive chair is the best to work with", but, nothing is further from reality than that statement. Additionally, we have compiled comments such as, "I have a pain in my back that is killing me, it must be the chair I have in the office", but such statement is invalid if it is not supported by the assessment of an occupational physician or a specialist in the area. On the other hand, it cannot be said that one chair is more ergonomic than another, based only on its beauty, its cost, or because the store vendor told us that "this is the latest technology in ergonomic chairs."
To make the choice of a work chair from the ergonomic point of view, several factors must be known to determine which characteristics are best suited to the task to be performed, always thinking about comfort and quality improvement. life of the user. Among the essential aspects that we must consider are:
1. The Technical Standards that apply to the design and adaptation of workstations.
2. The type of work to be performed.
3. Work standing, sitting or alternately.
4. The task is to be performed by leaning forward, rotating, making constant use of the upper extremities. This aspect will give us the height of the backrest required to allow ease of movement.
5. Working in a semi-sitting posture requires the use of a footrest in the chair.
6. If the Work requires keeping the head raised for a long time, the chair must have a backrest that covers the entire length of the back (lumbar, dorsal and cervical area).
7. To perform computer tasks, the backrest must cover both the lumbar and dorsal areas.
8. If a lot of movement is required, the backrest should only cover the lumbar area of the back, to allow free movement; for example, supermarket cashiers.
9. If the user presents any deviation condition in the spine such as lordosis, kyphosis or scoliosis, his spine should be studied to determine if the curvature of the chair adapts to his specific conditions.
Bibliographic review
• Mondelo, Barrau, Gregori and Blasco, Ergonomics 3: Design of Jobs, 1999, Mutua Universal, UPC editions.
• Gonzáles and Fernández, Ergonomics 4: Office Work, 2001, Mutua Universal, UPC editions.
• JL Melo, Practical Ergonomics - Guide for the ergonomic evaluation of a job, 2009, Fundación MAPFRE.
• National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), www.niams.nih.gov/portal_en_espanol/.
