Background
Ergonomics is a field study that involves the application of knowledge about physical, psychological, and biomechanical abilities and limitations of the human body. This knowledge is applied to the planning, design, and evaluation of work environments, jobs, tools, and equipment to improve worker performance, safety and health. In layperson terms, ergonomics is fitting the job to the worker; with the intent to prevent work related musculoskeletal disorders (WMSDs). OSHA publication 3125 states that WMSDs account for 34% of all lost-workday injuries and illnesses accounting for $1 of every $3 of workers compensation cost. Each year WMSDs account for more than $20 billion in worker’s compensation costs, with direct costs totaling as much as $50 billion annually.
Musculoskeletal Disorders (MSDs)
MSDs are injuries and disorders of the muscles, tendons, ligaments, joints, peripheral nerves, bones, supporting blood vessels and cartilage. These disorders have been called a variety of names, including trauma, repetitive stress injuries, and occupational overexertion syndrome. MSDs are painful, often disabling injuries that are not typically due to acute events but occur slowly over time affecting the arms, back, hands, wrists, fingers, legs, neck, and shoulders. The disorders include carpal tunnel, sciatica, herniated discs, and low back pain.
Work-related Factors
Work related MSDs occur when the worker’s physical capabilities do not meet the physical requirements of the job. Work related factors include:
- Postures – awkward (non-neutral) and static
- Forces – including heavy, frequent, or awkward lifting
- Compression
- Repetition
- Vibration
The following workplace conditions contribute to, but do not cause MSDs. These conditions include duration, intensity, temperature, and stress. Consider a scenario involving an abrasive blaster or a coating applicator continuously exposed to the vibrations associated with the abrasive or coating passing through the blast nozzle or spray gun. The continuous long-term exposure to the workers fingers and hand may lead to Reynaud’s syndrome or white finger. In Reynaud’s syndrome, smaller arteries that supply blood to your skin narrow, limiting blood circulation to affected area (vasospasm). Symptoms include numbness, tingling, ashen skin, loss of feeling and control of the affected body part. To be diagnosed, the symptoms must be persistent and occur without provocation by immediate exposure to vibration. The symptoms suddenly appear and are precipitated by exposure to cold. Continuous exposure to vibrations may lead to the symptoms becoming more severe, and the pathology potentially becoming irreversible.
Non Work-related Factors
Risk factors not related to a job can contribute to or cause MSDs. The factors include:
- Age
- Gender
- Hobbies
- Smoking
- Obesity
- Pregnancy
- Previous injury
- Medications
- Fatigue
- Physical conditions
We all age, and as we age, our body’s ability to heal slows causing longer recover time from ergonomic exposures. Due to anatomical and hormonal differences, certain MSDs are more prevalent in females. Hobbies such as working on a vehicle, or using power tools expose the body to vibration and forces increasing the probability of an ergonomic injury or illness. Smoking is linked to back pain; and smokers tend to heal more slowly due to reduced oxygen in the blood stream. Obesity causes a lack of flexibility, which causes fluid buildup, and increases pressure on the discs of the back. Carpal tunnel syndrome (CTS) is linked to pregnancy. Even a low exposure to risk factors can cause CTS in a pregnant woman. Fortunately, the symptoms usually disappear after the baby is born. Medications can cause dehydration, swelling, decreased, or increased metabolic rates, and a change in electrolyte levels. Physical conditions such as poor fitness combined with elevated body weight cause weariness and fatigue, which are recognized factors that contribute to MSDs.
Types of Work that Perpetuate Ergonomic Injuries
Considering posture, repetition, vibration, forces, and compression have the potential to cause MSDs, all types of work pose ergonomic hazards. The disorders occur most frequently in jobs involving manual handling, heavy lifting, twisting movements, long hours working in an awkward position, and even repetitive motion. This covers most of the workers in the coatings industry from the individual confined to an office continuously using a computer to the workers in the field or shop.
Parts of the Body Most Affected
MSDs have the potential to affect all tissue in the human body such as the nerves, tendons, tendon sheaths, muscles, and spinal discs. More commonly, MSDs affect areas of the arms and back. Common arm MSDs include tendon disorders such as tendonitis, tenosynovitis, De Quervain’s disease, trigger finger, Reynaud’s disease, and carpal tunnel syndrome. Tendon disorders often occur at or near the joints where the tendons rub against other tendons, ligaments, or bones. Symptoms include aching sensations, discomfort with specific movements, and tenderness to the touch. CTS, which affects the hands and wrist by compressing and entrapping the median nerve where it passes through the wrist into the hand causes numbness or severe pain in the wrist and hand. Other symptoms of CTS include a lack of strength in the hand and wrist, and the inability to make a fist. Workers frequently cite back disorders as a common source of pain and they account for significant loss of production and large compensation cost. Pulled or strained back muscles, or damage to the spinal discs are the most common back injuries. Repetitive pulling and straining causes damage to the back muscles, discs and ligaments, and leads to scarring and weakness that decreases the ability of the worker to support the back. This increases the probability of added injuries.
Detecting and Preventing Ergonomic Hazards
Addressing ergonomic hazards leads to the prevention of MSDs. Detecting and preventing ergonomic hazards starts with developing and implementing an ergonomics program that includes the following elements:
- Management commitment and employee participation
- Job hazard analysis
- Controlling ergonomic risk
- MSD management
- Training and education
The program provides employees with channels such as an established safety committee and supervisors to communicate their ergonomic exposures and concerns. The implementation of the program includes encouraging employees to take part in the program, and the decisions affecting their safety and health, creating an environment that is all inclusive, and respectful.
