Ergonomics
VIJAIARASAN P.A(MIIRSM)(Tech IOSH)
Environment, Health and Safety Manager at Danieli Group
Ergonomics is the science of fitting jobs to people. Ergonomics encompasses the body of knowledge about physical abilities and limitations as well as other human characteristics that are relevant to job design. Ergonomics design is the application of this body of knowledge to the design of tools, jobs, and the workplace for safe and efficient use by workers. Good ergonomics design makes the most efficient use of worker capabilities while ensuring that job demands do not exceed those capabilities.
Ergonomics Muscular-Skeletal Disorders
Muscular-Skeletal Disorders from improper ergonomics are any injury or illness of soft tissues of the upper extremity (fingers through the upper arm), shoulders and neck, low back, and lower extremity (hips through toes) that are primarily caused or exacerbated by workplace ergonomics risk factors, such as sustained and repeated exertions or awkward postures and manipulations. Included are disorders of the muscles, nerves, tendons, ligaments, joints, cartilage, and spinal disks. Medical conditions generally develop gradually over a period of time & do not typically result from a single instantaneous event. MSDs do not include injuries caused by slips, trips, falls, or other similar accidents. They can differ in severity from mild periodic symptoms to severe chronic and debilitating conditions.
Examples of MSDs from improper ergonomics include:
Symptoms of MSDs are physical indications that MSDs are developing. Symptoms can vary in severity depending on the amount of exposure the employee has had. Often symptoms appear gradually as muscle fatigue or pain at work that disappears during rest. Usually, symptoms become more severe as exposure continues (e.g., tingling continues when your employee is at rest, numbness or pain makes it difficult to perform the job, and finally pain is so severe that the employee is unable to perform physical work activities). Examples of symptoms of MSDS from improper ergonomics include:
Stages of Musculoskeletal Injuries
Musculoskeletal injury may progress in stages: early, intermediate and late.
Early Stage:?The body aches and feels tired at work but symptoms disappear during time away from work. Early warning signs, for example, sore shoulders and neck pain, often occur after the work activity stops (e.g. when driving home after a day of work). The effects may also be noticed the next morning such as aches and stiffness in the limbs or hands. The injury does not interfere with the ability to work and should heal completely if appropriate precautions are taken. At this stage, there are often no visible signs of a problem.
Intermediate Stage:?The injured area aches and feels weak near the start of work and continues until well after work has ended. Work becomes more difficult to do. However, the injury will still heal completely if dealt with properly. Visible signs may be present.
Late Stage:?The injured area aches and feels weak, even at rest. Sleep disturbance is a common complaint. Even non-demanding tasks are very difficult. The injury may not heal completely but effects can be eased if dealt with properly. Visible signs may be present. Not everyone goes through these stages in the same way. It may be difficult to say exactly when one stage ends and the next begins. The first sign of pain is a signal the muscles and tendons should rest and recover and that medical attention may be required. If there is no recovery an injury can become longstanding and sometimes irreversible. The earlier workers recognize signs & symptoms, the quicker the employer will be able to respond.
Ergonomics Muscular - Skeletal Disorder (MSD) Risk Factors:
Risk hazards consist of numerous ergonomics elements such as conditions of a job process, work station, or work method. Not all the below-listed risk factors will be present in every MSD-producing task, nor is the existence of one of these factors necessarily sufficient to cause an MSD from improper ergonomics.
Environmental Ergonomics Factors:
Heat/Cold: Excessive heat and humidity affect the body's blood circulation and cause cramps, burns/rashes, and general discomfort. Cold exposures also affect the body's blood circulation and cause hypothermia, loss of flexibility, distraction, and poor dexterity. A generally comfortable temperature range is 68 to 74 degrees Fahrenheit - +/-10 degrees depending on the physical workload - with humidity between 20 to 60 percent.
Noise Level/Peaks: Excessive noise levels above 90 decibels (dBA) and noise peaks above 100 decibels (dBA) cause headaches and increase blood pressure, muscle tension, and fatigue. High exposure over a long period of time causes deafness and other audiological disorders. Short-term exposure causes irritability and distraction.
Illumination: Under-and-over-lighted areas causes headaches, muscle strains, fatigue, and eye injury. It affects the body by reducing visual acuity, distractions, and glare interference. Poorly lighted areas also provide an atmosphere for trip/fall hazards and poor coordination. Illumination is measured with a light meter, similar to that used by a photographer. Recommended illumination (measured in foot-candles) by job type: Job Foot-candles
? General assembly 55 to 150
? Inspections 100 to 150
领英推荐
? Warehouse 50 to 100
? Storage 10 to 50
? Offices 100 to 200
Ergonomics Vibration: Excessive vibration causes pain to muscles, joints, and internal organs; causes nausea and trauma to the hands, arms, feet, and legs. Vibration is measured by its direction, acceleration, and frequency on the body.
Ergonomics Environment: Otherwise known as work stress, included in this category are salary administration, job positions, rest breaks, Employee attitude, and boredom. Keeping the Employment Environment upbeat is difficult; however, light-colored, well lighted, un-crowded,, and clean areas provide a positive environment. Employees should rest often depending on their work activity and temperature. Keeping the job moving and variation in activity reduces boredom.
PRIMARY RISK FACTORS
Force
The force that a worker exerts on an object is a primary risk factor. Muscles and tendons can be overloaded when a strong (high) force is applied against the object (load). Risk can also occur when a weaker (low) force is applied repeatedly (repetition) or continuously over a long period of time (duration). Exerting high or low muscle force can interfere with circulation, lead to muscle fatigue and tissue damage.
These conditions can result from:
Factors that affect the amount of force applied include:
Factors affecting grip force include:
The effects of these forces can be made worse by:
Ergonomics Work Station Design
Using an old rule-of-thumb, if we try to design something that everyone can use, no one will be able to use it. The same principle holds true with ergonomic workstation design. The idea of ergonomic workstation design is to make it fit the user. It will have to be adjustable for many body heights, sizes, weights, and reaches whether sitting or standing.
One of the first principles in Work Station Design is to consider the tallest Employee and the Employee with the shortest reach. The reason being is that we can not shorten an Employee's height or lengthen an Employee's reach. Platforms can be used to raise shorter Employees to the proper work height. Either sitting or standing, the Employee should be comfortable at his workstation. The arms should rest at the Employees sides and the Employee's back/neck should be kept straight; therefore, the work level must be waist-high.
Standing in one place for prolonged periods may lead to a host of injuries. Sit/stand workstations should be considered. If an Employee has to stand, provide something to lean on so the Employee will have the opportunity to rest. Also, providing a heavy rubber pad to stand on will help relieve neck, shoulder, back, and leg stress. Some common injury-prone positions with the body effect are as follows:
?Click the below link to know more in detail about ergonomics, guidelines, OSHA fact sheet, safety check sheets,?and Dos and Don ts for a workstation, etc.