What is Ergonomics?
Ergonomics means finding ways to work easier and just as productive. The goal of the science of ergonomics is to find the best fit between the worker and job conditions. Ergonomics tries to come up with solutions to make sure workers stay safe, comfortable, and productive.
Ergonomics also means working smarter, not harder. It looks at the following risk factor categories to see how the job can best fit the worker:
- Risk factors inherent in the worker. Physical, psychological and non-work-related activities may present unique risk factors.
- Risk factors inherent in the task. Work procedures, equipment, workstation design may introduce risk factors
- Risk factors inherent in the environment. Physical and psychosocial “climate” may introduce risk factors.
Ergonomic hazards can cause painful and disabling injuries to joints and muscles on a construction site. Per the Occupational Safety and Health Administration (OSHA), ergonomic hazards are the most frequently occurring health hazards in construction and the cause of most injuries.
In a recent survey, 40 percent of construction workers said: “working hurt” is a major problem. Working hurt reduces productivity, but continuing to work hurt can result in disabling injuries that end a career. Many laborers retire by age 55 because they just can’t do the work anymore. Many can’t enjoy their retirement because of their disabilities.
Risk Factors Inherent in the Worker
Each worker’s ability to respond to the external demands of a task is different and unique. Studies show that stereotyping or making general assumptions about an employee’s ability based on any one of the factors listed below is not correct. The studies described below emphasize the fact that you can’t group workers into broad categories. Everyone is unique and work needs to be designed to match each employee’s unique abilities. The only way to really know what employees can do is to interview and evaluate them based on the inherent factors listed below:
Age: The prevalence of ergonomics injuries increases as people enter their working years. By the age of 35, most people have had their first episode of back pain. Once in their working years, the prevalence is relatively consistent. Musculoskeletal impairments are among the most prevalent and symptomatic health problems of middle and old age.
Gender: Whether the gender difference seen with some musculoskeletal disorders (MSDs) in some studies is due to physiological differences or differences in exposure is unclear. One study concluded that the lack of workplace accommodation to the range of workers’ height and reach may, in part, account for the apparent gender differences.
Physical activity: Physical activity may cause injury. However, the lack of physical activity may increase susceptibility to injury. We can define “fitness” as combinations of strength, endurance, flexibility, musculoskeletal timing, and coordination. There is clear evidence that stretching exercises do have a positive effect on the reduction of MSDs.
Strength: A worker’s strength is important, but not necessarily the key. “Heavy work” stresses the heart and lungs which may result in rapid fatigue – general or localized. The probability of injury increases as muscles weaken. Consequently, demanding repetitive or static muscular
work requires energy, not necessarily strength. You may be strong, but not have sufficient energy to do the task.
Anthropometry: Designing for only the “average” person causes problems for everyone else. Anthropometry is the science of studying the difference in body size and proportions by measuring various body characteristics, including weight, physical range of mobility, and body dimensions. This information is then used by designers to engineer tools, equipment, furniture, and workstations for maximum efficiency for each individual worker.
Risk Factors Inherent in the Task
In addition to considering the worker attributes that may increase the risk of injury, we must also analyze the risk factors the work task itself brings to the job. We look at the task variables in the workplace that may increase or decrease the risk of cumulative trauma disorders (CTDs) depending on its design and location.
In large measure, work processes are determined by the factors below:
Force: Forcefulness is the amount of physical effort required by the person to do a task and/or maintain control of tools and equipment. Examples of work activities that exert force on the body include any job that requires: lifting, lowering, pushing, pulling, pinching, pounding, hitting, and jumping.
Vibration: The duration of exposure to vibration plays a large role in the effects of vibration forces. There are two basic types of vibration that can result in MSDs:
- Segmental vibration: When handling vibrating tools for a prolonged duration, vascular insufficiency in the hand and fingers can also result in interference with sensory receptor feedback. If a worker can’t “feel” the grip properly, he or she may compensate by applying more force than is necessary to hold and handle an object. Segmental vibration has also been linked to carpal tunnel syndrome.
- Whole body vibration: When the whole body is subjected to vibration, as most commonly experienced by truck drivers, there is an enhanced risk of injury, especially to the lower back.
Repetition: Repetition is a measure of how frequently we complete the same motion or exertion during a task. The severity of risk depends on:
- the frequency of repetition,
- speed of the movement or action,
- the number of muscle groups involved, and
- the required force during movement.
Recovery time: Recovery time is a measure of the rest (or low-stress activity) period available to the muscle group between similar exertions. Recovery time is important in preventing muscle fatigue because oxygen and metabolites can rejuvenate while uric acid and other waste products are removed from the muscle group. The recovery time needed will lengthen as the duration of the task increases.
Duration: Duration is a measure of the length of time of exposure to a risk factor. Of course, the assumption is that the longer the duration of exposure, the greater the risk of injury. The duration may be measured in seconds, minutes, hours, days, weeks, months, and even years.
As with most individual risk factors, the duration must be considered along with other people, tasks, and environmental risk factors such as the physical conditioning of the worker, posture, force, weight, temperature, stress, etc.
Twisting: Twisting in the middle of a lift greatly amplifies the forces on the lower back. The point at which twisting is most likely to cause an injury when lifting objects is in the middle of the lift. Material handling and brickwork are good examples of tasks that require twisting.
Posture: Posture is the position of the body while performing work activities. An awkward posture is a deviation from the ideal working posture of arms at the side of the torso, elbows bent, with the wrists straight. Awkward postures typically include reaching behind, twisting, working overhead, kneeling, forward or backward bending, and squatting. If the posture is awkward during work, there is an increased risk for injury. The more the joint departs from the neutral position, the greater the likelihood of injury.
Listed below are some specific postures that may be associated with increased risk of injury:
- Extending or flexing the wrist, up and down, regularly is associated with a greater risk of carpal tunnel syndrome.
- Bending the hand toward the little finger regularly greater than 20 degrees increases the risk of pain and other issues.
- Raising the arms which flexes the shoulders greater than 60 degrees for more than one hour a day increases the risk of acute neck and shoulder pain.
- Hands working at or above shoulder level can result in increased risk of tendinitis and various shoulder problems.
- The greater the angle of the neck moves forward, backward or side to side, the more quickly neck and shoulder pain results.
- Bending at the lower back while working increases the likelihood of low back disorders.
Risk Factors Inherent in the Environment
Environmental risk factors that refer to the physical and psychosocial climate in the workplace include:
- Illumination – Inadequate light can increase the number of attempts in completing a task.
- Sound – Sound can be an irritant to increase stress.
- Humidity – Humidity has an impact on worker endurance which affects the duration with which work can be conducted safely.
- Temperature – Be it too hot or too cold, in combination with any one of the above risk factors may also increase the potential for MSDs to develop.
- Psychosocial – Psychosocial work demands in terms of job control, psychological demands, social support and job dissatisfaction all can influence the rate at which employees are injured. If your employer forces employees to work fast, not safe, the likelihood of MSDs increases.