Construction Solutions - Masonry, Cement & Plaster - Operating power vibrator to compact concrete or grout



Hazard Analysis


	Work Activity:	Masonry, Cement & Plaster
	Task:	Operating power vibrator to compact concrete or grout
	Hazard:	Stooped postures

Problem:

Operating power vibrator to compact concrete or grout may involve work in stooped postures. The ‘stooped’ position is characterized by prolonged periods of back forward bending, which is considered an extreme back posture.

Risk Description:

The ‘stooped’ position, characterized by prolonged periods of forward bending of the back, is considered one type of extreme back posture that is a risk factors for low back pain (LBP) and disorders of the low back. Working in a stooped posture while operating power vibrator to compact concrete or grout can increase the forces within the low back. The cumulative effects of stooped postures may lead to LBP or low back disorders, such as strains of the muscles, sprains of the ligaments surrounding the spine, or intervertebral disc problems.

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Low Back Pain and Disorders

Low back pain (LBP) is among the most common health complaints in working-aged populations worldwide. In the U.S., 70%-80% of adults will experience a significant episode of LBP at least once in their lives. Low back disorders are conditions associated with lifting and other forceful movements of the back. Episodes of LBP are characterized by varying levels of pain and symptoms in the low back (lumbar spine). Low back disorders can even cause leg pain at times.

Work-Related Risk Factors

Work-related lifting and forceful movements
Whole body vibration
Awkward postures (bending and twisting)
Heavy physical work
Poor job satisfaction, perception of intensified workload, lack of job control, and certain personality traits
Lifestyle factors associated with LBP include smoking, a sedentary lifestyle, and obesity

Development and Progression

The low back may be injured due to either a sudden stressful event or the cumulative effect of stressful activities. Strains of the muscle or sprains of the ligaments surrounding the spinal joints occur most commonly. Injuries to the low back may also involve the intervertebral disc.

The intervertebral disc is composed of a ring of fibers surrounding a sac of fluid or gel-like material. Discs may be damaged due to a sudden stress (e.g. a fall, slip, or catching an unexpected load), or due to cumulative problems when stressful activities stretch, tear, or unravel the protective fibers surrounding the sac of fluid. When the fibers can no longer contain the fluid, small leaks or bulges can occur or the disc may flatten. The most commonly injured low back discs are between the 4^th and 5^th lumbar vertebrae (L4-L5), and between the 5^th lumbar vertebrae and the sacrum (L5-S1). Disc problems may lead to a pinched nerve.

The causes of many episodes of LBP are unclear. Even with clinical tests and imaging procedures, about 85% of patients cannot be given a precise diagnosis. The pain in these cases is presumed to be related to muscle, ligament, or tendon injury or degenerative changes.

Common Symptoms

Individuals with low back problems typically experience pain in the low back (lumbar spine). Leg pain may accompany low back pain. Often, leg pain is localized to the side or back of the thigh, but sometimes the pain may go all the way to the foot. This leg pain is called "sciatica." Individuals may also have tenderness in the low back and a limited range of motion for bending forward, backward, sideways, or twisting. Bending forward tends to increase pain levels.

Common Treatment

Initial treatment for most episodes of low back pain includes avoidance of stressful activities and occasionally one to two days of bed rest. Nonsteroidal anti-inflammatory drugs (NSAIDs, e.g. ibuprofen or naproxen) are often helpful, and stronger drugs may be prescribed (muscle relaxants or narcotics) for more severe, acute pain. Other treatment options may include application of heat and cold, physical therapy, spinal manipulation, or injections. Some LBP cases may require surgery (ruptured disc or severe trauma cases).

Most workers with occupational LBP get better. Half of workers improve in one week and 90% improve in 30 days, regardless of treatment. Light duty work activities may be prescribed by the physician during the recovery period. The remaining 10% of workers may have a chronic condition and may not be able to return to their previous jobs. Many workers may suffer from residual pain that may affect work or activities of daily living.

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Level of Risk:

Work loads or activities are of such a magnitude and character that a significant number of workers risk developing an MSD in the short or long term.

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Assessment Info:

To assess exposure to stooped postures, determine how many hours per day the worker spends in with their back bent forward >30º, bent forward >45º, or twisted >30º. Also, visit Thomas Bernard’s website for a host of practical ergonomic tools.

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Solutions:

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Participatory Ergonomics Program

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Participatory Ergonomics Program

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Regulations & Standards:

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