WORKPLACE ENVIRONMENT AND ERGONOMICS (OSHA)

4.0 WORKPLACE ENVIRONMENT AND ERGONOMICS 

4.1 (A) History of Ergonomics

     Ergonomics is the science (and art) of fitting the work environment to the employee (Chad Cooper and Brian H. Kleiner, 2001). The word Ergonomics is derived from the Greek words “ergos” and nomos”. “Ergos” means work meanwhile “nomos” means principles of laws (Evelyn Tan Guat Lin, 1996). These combinations give us the phrase ergonomics, which mean the science of work. Ergonomics is not a new science, although the term has become common lately. Ergonomics seeks to improve the match between the job and man’s physical abilities, information handling and workload capacities. By improving the match between the work environment and the employee, you can expect improved employee comfort, reduced chances for occupational injuries, improved productivity, and improved employee job satisfaction.

     International Labor Organization (ILO) defines ergonomics as the application of the human biological sciences in conjunction with the engineering sciences to the worker and which at the same time enhances productivity. This definition emphasizes the important triad of ergonomics elements namely comfort, health and productivity. Thus ergonomics seeks to adapt work to human physical and psychological capabilities and limitations. In seeking this goal, it draws on many disciplines including anatomy, physiology, psychology, sociology, physics and engineering (Evelyn Tan Guat Lin, 1996).

4.1 (B) Statutory requirements related to ergonomics in OSHA 1994

     In the other hand, Occupational Safety and Health Act 1994 (OSHA 1994) has defines ergonomics as the science of “designing the job to fit the worker, instead of forcing the worker to fit the job”. However, generally ergonomics is defines as fitting the job (tools, tasks, and environment) to the employee, instead of forcing the worker to fit the job. Ideally, ergonomics makes the job safer by preventing injury and illness, makes the job easier by adjusting the job to the worker, makes the job more pleasant by reducing physical and mental stress and in the same time it saves money.

     Chad Cooper and Brian H. Kleiner define ergonomics as the study of equipment design in order to reduce operator fatigue and discomfort. Also known as human factors or human engineering it basically describes the interaction between an employee and their job functions, with the emphasis being on reducing unnecessary physical stress in the workplace. Ergonomics also can be defines as a discipline concerned with all aspects of designing for people (Ann Brooks, 1998).

     Besides that, ergonomics is the practice of learning the practice of learning about human characteristics and then using that understanding to improve people’s interaction with the things they use and with the environments in which they do so 10(Wilson, 1995). Board of Certification for Professional Ergonomists (BCPE) defines ergonomics as a body of knowledge about human abilities, human limitations and human characteristics that are relevant to the design of tools, machines, systems, tasks, jobs, and environments for safe, comfortable and effective human use.

     Ergonomics also is a discipline or science of fitting workplace conditions and job demands to the capabilities of the worker. Many consider ergonomics a multi disciplinary field of applied science where knowledge about human capabilities, skills, limitations, and needs is taken into account when examining the interactions among people, technology, and the work environment (Westgaard and Winkel 1997;Cohen et al. 1997).

4.1 (C) Objectives Of Ergonomics

     Ergonomics is the application of human biological sciences to in combination with engineering science to achieve a good matching of capabilities and limitations of human mind and body to the requirements of work.

The major objectives of ergonomics include the following.

-Secure health, safety and comfort of persons doing the work.
-Improve the comfort and utility of various equipments and facilities, such as furniture and dwelling   units, used by people by matching their design with physiological characteristics o their intended users
-Achieve better work efficiency and effectiveness.


4.2 UNDERSTAND WORKSTATION DESIGN PRINCIPLE

4.2 (A) Illustrate Sitting Work Position

Sitting
 

     A well-designed chair for the operator is one of the most important parts of a work station. It can favorably affect posture, circulation, the amount of effort required to maintain a position, and the amount of pressure on the spine.

    The following recommendations should be followed: 

• The front of the seat should be of a "waterfall" design in order to provide sufficient clearance for the flesh of the thigh and to prevent reduction of blood circulation.
• For tasks requiring frequent lateral movements, seats should swivel.
• In order to achieve satisfactory posture it may be necessary to adjust the work station height. This is the reason that typewriters and computer terminals are often placed on a lower work surface at secretarial work stations.
• Hand rests should be provided for intricate tasks such as fine assembly or inspection. With the weight of the arm supported, the hand is stabilized improving hand dexterity and comfort.
• The seat should adapt to the user, not vice versa.
• Chairs should be stable and fully and easily adjustable from the seated position.
• Seat pans and backrests should be upholstered and covered in a material which absorbs perspiration. A 20mm compression is about firm enough.\
• Seat pan height should be adjustable and should transfer the user's weight through the buttocks, not the thighs.

GOOD POSITION BAD POSITON

EXAMPLE OF GOOD WORKPLACE DESIGN

4.2 (B) Illustrate Standing Work Position

Standing 

Here are some guidelines for optimum posture for standing jobs:

      Avoid having operators stand still in one place for unduly long periods of time. The activity of the leg muscles acts as a pump and assists the veins in returning blood to the heart. Prolonged standing stops this pumping action and this causes swelling of the lower extremities.

     Provide a rubber or padded mat where prolonged standing cannot be avoided. This should reduce fatigue and improve comfort.

EXAMPLE OF STANDING POSITION


4.3 UNDERSTAND ERGONOMIC RISK

4.3 (A) Explain Musculo-Skeletal-Disorders

MUSCULOSKELETAL DISORDERS

      Musculoskeletal disorders are among the most common of human afflictions. They affect all age groups and frequently cause disability, impairments, and handicaps. They consist of a variety of different diseases that cause pain or discomfort in the bones, joints, muscles, or surrounding structures, and they can be acute or chronic, focal, or diffuse. Approximately 33 percent of U.S. adults are affected by musculoskeletal signs or symptoms, including limitation of motion or pain in a joint or extremity. In one study of Detroit residents who kept track of daily health symptoms in a diary, musculoskeletal symptoms constituted the most frequent category of health symptoms. The prevalence of musculoskeletal disorders generally increases with age, with the majority of persons aged seventy-five and over having some form of musculoskeletal disorder, especially arthritis.

      Not only are musculoskeletal disorders highly prevalent, but, because of their association with aging, they are likely to become more prevalent as the population ages throughout the world. All racial groups are affected. While many of these disorders are not devastatingly disabling to affected individuals, their prevalence is so great that more mobility and other limitations are accountable to these disorders than to any other type. While much of the substantial cost of these disorders is due to the medical care and medications and other treatments required by patients, the preponderance of costs is due to work loss, which is a frequent consequence of these disorders.

      Contained within the broad category of musculoskeletal disorders are a number of specific diseases and causes of pain, several of which affect a large percentage of the population. Musculoskeletal disorders range from back pain to rheumatoid arthritis and gout, and include different types of arthritis, tendinitis, and musculoskeletal pain. The most common musculoskeletal disorders are listed in Table 1, along with their point prevalence among adults in Western populations. The most prevalent disorders are low back pain, osteoarthritis, and so-called soft tissue rheumatism. Even though they afflict millions of persons around the world, several of the common musculoskeletal disorders fall into the category of moderately prevalent, including gout, a form of episodic arthritis; fibromyalgia, a disorder of diffuse muscular pain and a subtype of soft tissue rheumatism; and rheumatoid arthritis, an inflammatory systemic disorder that causes widespread joint pain.


Signs of musculoskeletal disorders.

Common Causes of Musculoskeletal Disorders

4.4 UNDERSTAND WORKPLACE ENVIRONMENT

4.4 (A) Indoor Air Quality and its Effect on Respiratory System

      The human health effects of poor air quality are far reaching, but principally affect the body's respiratory system and the cardiovascular system. Individual reactions to air pollutants depend on the type of pollutant a person is exposed to, the degree of exposure, the individual's health status and genetics. People who exercise outdoors, for example, on hot, smoggy days increase their exposure to pollutants in the air.

      The health effects caused by air pollutants may range from subtle biochemical and physiological changes to difficulty breathing, wheezing, coughing and aggravation of existing respiratory and cardiac conditions. These effects can result in increased medication use, increased doctor or emergency room visits, more hospital admissions and even premature death.

The health of our lungs and entire respiratory system is affected by the quality of the air we breathe.  In addition to oxygen, this air contains other substances such as pollutants, which can be harmful.  Exposure to chemicals by inhalation can negatively affect our lungs and other organs in the body.  The respiratory system is particularly sensitive to air pollutants because much of it is made up of exposed membrane.  Lungs are anatomically structured to bring large quantities of air (on average, 400 million litres in a lifetime) into intimate contact with the blood system, to facilitate the delivery of oxygen.

Lung tissue cells can be injured directly by air pollutants such as ozone, metals and free radicals.  Ozone can damage the alveoli -- the individual air sacs in the lung where oxygen and carbon dioxide are exchanged. More specifically, airway tissues which are rich in bioactivation enzymes can transform organic pollutants into reactive metabolites and cause secondary lung injury.  Lung tissue has an abundant blood supply that can carry toxic substances and their metabolites to distant organs.  In response to toxic insult, lung cells also release a variety of potent chemical mediators that may critically affect the function of other organs such as those of the cardiovascular system.  This response may also cause lung inflammation and impair lung function.

4.4 (B) Measure Lightning and Sightedness

Lightning.

When planning the layout of Visual Display Unit workstations the following points should be considered with regard to lighting.

Avoid:

· Gloom and harsh light equally.

· Glare from unshielded light sources, artificial and natural, and reflections in the operator's field of view.

·Screen reflections.

Ensure:

· Levels of 300-500 lux on the working plane.

· Use of diffusers with a narrow angle of light distribution on overhead light sources or provide diffuse lighting from indirect sources, complemented where necessary with task lighting.

· Low reflectance work surfaces and equipment with matt finished surrounds.

· Where possible locate screens between and parallel to overhead light units and at right angles to windows. Screens should never face or back on to windows unless adequate control of daylight glare is available.

· Where indirect lighting or low luminance light sources are used, ensure that the surface reflectivity of walls, ceilings and floor are higher than that used for other forms of lighting.

Screen Filters

              Display screen filters may prove an effective means of minimising screen glare. However, as the filter will diminish the clarity of the screen display, they should be considered only as a last resort. There are many screen filters on the market and expert advice should be sought prior to selection.

Sightedness.

The screen and keyboard should be fully adjustable separately the chair and table height should be adjustable there should be sufficient desk space for laying out of work to suit the operator desk and equipment surfaces should be made of materials which do not produce glare or contrast brightness with input documents the VDU screen should be positioned at eye level and the distance between the hard copy and the screen should not be too large. The Association of Optometrists' advice is that the source documents and other work materials should not necessarily be at the same distance as the screen as the size of hard copy text is usually smaller than the characters on the screen. The shorter the working distance, the greater the risk of developing shortsightedness (Grundy, Rosenthal and Seymour 1991). Again the critical factor is adjustability to suit the individual operator all VDU operators should be able, without moving from their workstation or twisting uncomfortably, to look periodically into a distance of at least 20 feet to rest tensed eye muscles adjustable document holders should be available

a.    The work desk or work surface shall have a sufficiently large, low-reflectance surface and allow a flexible arrangement of the screen, keyboard, documents and related equipment

b.    The document holder shall be stable and adjustable and shall be positioned so as to minimise the need for uncomfortable head and eye movements.

c.    There shall be adequate space for operators or users to find a comfortable position.

d.    The workstation shall be dimensioned and designed so as to provide sufficient space for the operator or user to change position and vary movements.

e.    The symbols on the keys shall be adequately contrasted and legible from the design working position.

4.4 (C) Measure Temperature and Humidity

Temperature and relative humidity are two of several parameters that affect thermal comfort. Satisfaction with the thermal environment can also be influenced by such factors as radiant temperature, air velocity, occupant activity level, and clothing.

ASHRAE Standard 55-1992, Thermal Environmental Conditions for Human Occupancy, presents guidelines that are intended to achieve thermal conditions that at least 80% of the occupants would find acceptable or comfortable.

Relative humidity levels below 25% are associated with increased discomfort and drying of the mucous membranes and skin, which can lead to chapping and irritation. Low relative humidity also increases static electricity, which causes discomfort and can hinder the operation of computers and paper-processing equipment. High humidity levels can result in condensation within the building structure and on interior or exterior surfaces and the subsequent development of moulds and fungi. In most Canadian cities, ideal indoor relative humidity levels are 35% in the winter and 50% in the summer. ASHRAE specifies a range between 25 and 60%.

In large buildings, the air supply is humidified over the winter season, usually by a water spray or steam system. Water spray humidifiers require regular scheduled maintenance to control water quality. Steam humidifiers are cleaner and easier to maintain, but use more electrical power. In the summer, the air conditioning dehumidifies the outdoor air supply.

4.4 (D).Measure noise and hearing quality

      The term hearing describes the process, function, or power of perceiving sound. Hearing is second only to vision as a physiological sensory mechanism to obtain critical information during the operation of an aircraft. The sense of hearing makes it possible to perceive, process, and identify among the myriad of sounds from the surrounding environment. Anatomy and Physiology of the Auditory System The auditory system consists of the external ear, ear canal, eardrum, auditory ossicles, cochlea (which resembles a snail shell and is filled with fluid), and the auditory nerve. Ambient sound waves are collected by the external ear, conducted through the ear canal, and cause the eardrum to vibrate.

      Eardrum vibration is mechanically transmitted to the ossicles, which, in turn, produce vibration of a flexible window in the cochlea. This vibration causes a pressure wave in the fluid located inside the cochlea, moving thousands of hair-like sensory receptors lining the inner walls of the cochlea. The movement of these receptors resembles the gentle movement of a crop field caused by the wind. The stimulation of these sensors produces an electrical signal that is transmitted to the brain by the auditory nerve. This signal is then processed by the brain and identified as a particular type of sound.

Types of Noise

·         Steady: Continuous noise of sudden or gradual onset and long duration (more than one second). Examples: aircraft powerplant noise, propeller noise, and pressurization system noise. According to the Occupational Safety and Health Administration (OSHA), the maximum permissible continuous exposure level to steady noise in a working environment is 90 dB for eight hours.

·         Impulse/Blast: Noise pulses of sudden onset and brief duration (less than one second) that usually exceed an intensity of 140 dB. Examples: firing a handgun, detonating a firecracker, backfiring of a piston engine, high-volume squelching of radio equipment, and a sonic boom caused by breaking the sound barrier. The eardrum may be ruptured by intense levels (140 dB) of impulse/blast noise.

Effects of Noise Exposure

Physiological

• Ear discomfort may occur during exposure to a 120 dB noise.
• Ear pain may occur during exposure to a 130 dB noise.
• Eardrum rupture may occur during exposure to a 140 dB noise.
• Temporary hearing impairment. Unprotected exposure to loud, steady noise over 90 dB for a short time, even several hours, may cause hearing impairment. This effect is usually temporary and hearing returns to normal within several hours following cessation of the noise exposure.
• Permanent hearing impairment. Unprotected exposure to loud noise (higher than 90 dB) for eight or more hours per day for several years, may cause a permanent hearing loss. Permanent hearing impairment occurs initially in the vicinity of 4,000 Hz (outside the conversational range) and can go unnoticed by the individual for some time. It is also important to remember that hearing sensitivity normally decreases as a function of age at frequencies from 500 to 6,000 Hz, beginning around age 30.

Psychological

• Subjective Effects: Annoying high-intensity noise can cause distraction, fatigue, irritability, startle responses, sudden awakening and poor sleep quality, loss of appetite, headache, vertigo, nausea, and impair concentration and memory.
• Speech Interference: Loud noise can interfere with or mask normal speech, making it difficult to understand.
• Performance: Noise is a distraction and can increase the number of errors in any given task. Tasks that require vigilance, concentration, calculations, and making judgments about time can be adversely affected by exposure to loud noise higher than 100 dB.

How to Protect Your Hearing

·         Earplugs. Insertable-type earplugs offer a very popular, inexpensive, effective, and comfortable approach to provide hearing protection. To be effective, earplugs must be inserted properly to create an air-tight seal in the ear canal. The wax-impregnated moldable polyurethane earplugs provide an effective universal fit for all users and provide 30 to 35 dB of noise protection across all frequency bands.

·         Communication Headsets. In general, headsets provide the same level of noise attenuation as earmuffs, and are also more easily donned and removed than earplugs, but the microphone can interfere with the donning of an oxygen mask.

·         Active Noise Reduction Headsets. This type of headset uses active noise reduction technology that allows the manipulation of sound and signal waves to reduce noise, improve signal-to-noise ratios, and enhance sound quality. Active noise reduction provides effective protection against low-frequency noise. The electronic coupling of a low-frequency noise wave with its exact mirror image cancels this noise.

·         Combinations of Protection Devices. The combination of earplugs with earmuffs or communication headsets is recommended when ambient noise levels are above 115 dB. Earplugs, combined with active noise reduction headsets, provide the maximum level of individual hearing protection that can be achieved with current technology.

4.5 Appreciate the proper and safe methods of ergonomics in the workplace

This report has outlined some of the most common ergonomic problems, their causes and some actions we can take to reduce the risk of injury. But, as we know, ergonomics seeks ways to make the job fit the person, rather than the other way around. That means it is, by definition, a very individualized approach to designing tools, tasks and work areas.

Each individual body is different in terms of size, shape and capability. Each of us uses different tools and movements and sits, stands and moves in different positions in the course of a day. So any effort to make your workplace really ergonomic – to adapt jobs to people and not force people to fit their jobs – must involve every single person in the workplace.

If we ignore symptoms for too long, we may eventually be unable to perform our current job. We may have to permanently transfer jobs, undergo physical therapy, or even have surgery. In the very worst cases, we may develop such a major and painful disability that we were unable to work.

So pay attention to how our body feels when we were working. Try to identify what causes pain, numbness or other symptoms. Work with our supervisors to make sure we have a workplace that's free of ergonomic hazards.