Hey guys.
Welcome to this video over ergonomics.
Today we will be discussing the Human factors in ergonomics.
Ergonomics is defined as the relationship between people and their environment, including
tools, equipment, work area, vehicles, facilities, and printed material.
Good ergonomics improves output and performance and reduces error and accidents
by making the environment comfortable and user-friendly.
The four general principles of ergonomics that apply to safety engineering are as follows:
1.
People versus machines.
This principle states that people are better at some jobs, such as reasoning inductively
and handling unexpected occurrences, while machines are better at other jobs, such as
repetitive operations and deductive reasoning.
2.Change the job, not the person.
People have limits, and not recognizing those limits can be extremely detrimental.
It is better to change a job, equipment, or environment to fit the person rather than
trying to change the person to fit the job.
3.Work wisely.
Productivity can be gained and errors reduced by finding new and better ways to do a job.
4.Every individual is different.
People differ in their age, height, weight, reaction time, strength, coordination, attitudes, etc.
Designers and managers need to adjust jobs accordingly.
Fitness for duty
The term "fitness for duty" refers to an employee having the physical and mental capabilities
to fulfill the job demands.
For jobs with high physical demands especially, it can be important to objectively assess
fitness for duty to decrease chance of on-the-job injuries.
First, one must clearly establish in a written document what the physical requirements of
the job are, so there is a standard for comparison.
Second, there must be a way of determining whether an employee can meet these demands.
Physical therapists can assess physical capabilities and the amount of force an employee is able
to apply with a given muscle group.
Fitness for duty assessments are also important when determining if an injured employee is
capable of returning to full duty after recuperation.
Organizational, behavioral, and psychological influences on ergonomic injuries
Organizational, behavioral, and psychological factors can influence the likelihood and severity
of ergonomic injuries.
Organizational factors include how the work processes are designed and laid out, the time
demands that are placed upon the workers, and how long the cycle times are.
Workstation design is the most important organizational factor.
Behavioral factors that impact ergonomic injuries include observing proper lifting behavior,
observing the buddy system for lifts over 25 pounds, and observing proper neutral postures.
Poor postures may cause the employee to feel pain, which results in uneven muscle strains.
The most important psychological contributor to ergonomic injuries is stress.
Stress and perceived lack of control lead to poor job satisfaction and promote a feeling
of monotony at work.
These stress factors can increase perceptions of pain, decrease blood flow, create muscle
tension, and therefore increase the likelihood of an ergonomic injury.
When considering the likelihood of an ergonomic injury, tasks must be evaluated with regard
to four major stressors.
Repetition-how often does a certain movement have to be repeated during the work day
Higher numbers of repetitions create more stress on bones, muscles, and tendons,
thus increasing likelihood of injury.
Force-how much force must be applied when performing the task
Force also includes how much weight must be lifted.
Any lifting greater than 25 pounds is considered heavy.
The heavier the lifting (or force), the greater the likelihood of injury.
Posture-this refers to the orientation of the body or body part.
Neutral postures are the least stressful.
The farther from neutral the body is required to be, the greater the likelihood of injury.
Vibration-this refers to the amount of vibratory movement required.
Vibration is generally caused by holding power tools (e.g., a drill or jackhammer).
Exposure to vibration for long periods of time can damage nerves.
The most prominent commonality between all four risk factors is
the degree to which the body is being forced outside its normal state.
The greater the deviation or the higher the demand on the body, the greater the likelihood of injury.
An additional contributing factor is the amount of rest allowed between exposure to risk factors.
Over time, with insufficient rest, tendons and ligaments can become inflamed and painful
and can lead to an ergonomic injury.
Ergonomic injuries sometimes require surgery to correct.
This is a cost to both the employer and the employee.
Proper workstation design can minimize ergonomic risk factors.
One must determine first what the physical demands of the job are.
For example, in the case of an assembly operation, the items that must be used the most frequently
should be arranged in front of the worker at a distance that does not require an extended reach.
Items that are used much less frequently (such as one or two times per hour) can be placed
where some reach is required.
One should also arrange the work center and work flow so that body movements using different muscle groups
are alternated over the course of a shift.
For example, needing to walk is interspersed with movements that utilize upper body strength
to provide use of various body parts over the course of the shift.
The important design principle is not to overly fatigue one body part or muscle group with
excessive repetition, force, or angle of posture.
Aging workforce and ergonomic injuries
Many companies have an aging workforce.
An aging workforce refers to workers who have been employed for a long time and are approaching
what may have traditionally been considered retirement age.
Due to longer life spans and uncertainties about future social security payments,
people are working longer.
As people age, their physical fitness tends to decline.
Bones become more brittle, and muscles are not as strong.
In addition, some people develop arthritis in their joints as they age.
These factors may make it more difficult for the aging worker to perform physical functions on the job.
However, one cannot discriminate against a worker based on age and so cannot lay these workers off.
The best strategy is to redesign the physical demands of work to make it easier for these
workers to perform the job without injury.
This will benefit employers in the future because, over time, the social security retirement age is increasing.
The most common causes of work injuries are the following:
Overexertion, Impact accidents (where the injured person is struck by an object).
Falls from heights. Reaction to chemicals. Compression. Motor vehicle accidents.
Exposure to caustics, radiation, or extreme temperatures.
Abrasion or rubbing. Slips and trips.
Sprains and strains are the most common injury experienced
at work followed by bruises, cuts, and fractures.
The back is the most frequently injured part of the body, largely because of improper lifting techniques.
The next most frequently injured parts of the body are the legs (including knees and ankles), fingers, and arms.
Workplace injuries caused by repetitive motion have also increased, as more jobs require computer use.
According to the human factors theory of accident causation,
accidents are caused by human error resulting from the following:
Overload. Inappropriate response.
Inappropriate activities.
Overload occurs when a person's responsibilities are greater than their capacity at that moment.
Note a person's capacity can change and depends on natural ability and training, state of
mind, physical condition, and stress levels.
The following factors can also affect capacity: Environmental factors such as noise and temperature.
Situational factors such as clarity of the instructions and level of risk.
Inappropriate response refers to any actions before or after an accident that caused the
accident or make it more severe.
For example, seeing a hazard and not correcting it.
Inappropriate activities include jobs for which a person is not trained.
Powerlessness, mindlessness, and normlessness are all linked to automation in the workplace.
Powerlessness is when workers feel like they can't control the work environment.
Mindlessness occurs when workers do not have to think in order to perform their work.
Normlessness is when workers feel disconnected from society's rules, norms, and mores.
Meaninglessness is when workers feel a disconnection between their work and the finished product or service.
These problems can lead to lower productivity and work quality.
They are also linked to an increase in work-related accidents, absenteeism, turnover, and employee theft.
Workplace stress
Stress is defined as the body's response to perceived threats.
Stress can result in emotional problems such as anxiety
and aggression, behavioral problems such as clumsiness and trembling,
or cognitive problems such as problems concentrating or making decisions.
Workplace stress is a serious problem, costing over $150 billion dollars a year.
In fact, more than 15 percent of workplace disease claims are stress-related.
In addition to contributing to accidents and injuries, stress is also linked to lower productivity,
excess absenteeism and turnover, and poor morale.
Workplace stress generally stems from a poor fit between the employee and the job.
Specific issues can be poor physical working conditions, too much work or tasks that are
too complex, lack of feedback or control over job responsibilities, unpredictable work schedules,
and tense work relationships.
In addition, personal and family problems can also contribute to workplace stress.
Repetitive strain injuries, such as carpal tunnel syndrome, result from long-term, cumulative
trauma to tendons, muscles, ligaments, joints, nerves, and other soft tissues.
The hands, arms, neck, and shoulders are most subject to repetitive strain injuries.
Other types of repetitive strain injuries include tendinitis, Raynaud's disease, and fibromyalgia.
A safety program to reduce such types of injuries would include the following:
Work processes and designs that are simple to understand and use, not overly demanding physically,
and not boring or repetitive.
Procedures designed to improve safety and reduce injuries.
Training about the established procedures.
Monitoring and analysis of procedures and injuries to evaluate any changes needed to the safety procedures.
Workstation designs that can be adjusted to individual needs.
Availability of correct tools for each worker and each task.
Principles of workstation layout that affect workplace safety
Workstations need to be designed to make the work as convenient and comfortable as possible
so that workers remain safe and productive.
Generally, this means placing components where they can be easily seen and reached.
Four principles of workstation layout are importance, frequency of use, functionality,
and sequence of use.
Importance - Components that are the most important to the overall system should be the most prominent.
Frequency of use - Components that are used frequently should be conveniently located.
Functionality - Components that are functionally related should be grouped together.
Sequence of use - Components that are operated in sequence should be grouped together and
placed in the order they are used.
Physiological and psychological problems linked to computer monitors
Computer monitor use is linked to eye fatigue, blurred vision, eyestrain, and nervousness.
These eye problems can impair work performance, cause accidents, and lead to stress.
In addition to eye problems, computer monitor use can also lead to cumulative trauma disorders.
Setting up an ergonomic workstation helps to reduce these hazards.
The keyboard should be located in front of the user and tilted so the back is lower than the front.
The mouse should be placed within easy reach and the desk itself needs to be at a height
so the user doesn't have to slouch.
Changing work habits also helps.
Employees need to be encouraged to take regular breaks and to use a soft touch on the keyboard and mouse.
They should also avoid resting their wrists on any type of edge.
Other helpful strategies include reducing lighting levels and minimizing glare.
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