You may be surprised to learn, as I was, that a hazard described by one expert as “probably the No. 1 neuromuscular disorder in the world in manufacturing and construction environments, the most costly, and underappreciated,” is not the subject of its own OSHA construction standard.
I am referring to “Hand Arm Vibration syndrome,” also known as HAVS (and formerly known as “vibration white finger,” as a prime symptom of its circulatory and neural effects includes the blanching — pale and ashen appearance — of the fingers).
This malady, although identified by industrial physicians more than 100 years ago, is severely under-reported by workers and health professionals. Perhaps two million workers in the U.S. are at risk, of which as many as half will develop HAVS.
The syndrome is defined as a type of industrial disease that produces symptoms in the arms and hands, and damage to blood vessels, nerves, and other musculoskeletal structures, usually from the prolonged use of vibrating power tools in the workplace. Working in a cold climate, and smoking (which impairs circulation to the extremities) are additional risk factors.
Devices linked to HAVS include grinders, riveters, drills, jackhammers, chipping hammers, jigsaws, sanders, vibrating pokers and compactors, scabblers, and chainsaws. Of course, any kind of hand-held vibrating tool can contribute to HAVS, and regardless of whether the tool is powered by electricity, gasoline, or air. However, while the frequent use of vibrating hand tools having a frequency range between 8 Hz and 1500 Hz is problematic, the most hazardous frequency range is 100-150 Hz. In addition to construction and maintenance, workers in the mining and forestry industries are also very much at risk.
Initially, nerves are irritated by the vibration, resulting in tingling and numbness in the hand and fingers. At first, symptoms are most likely to be noticed while working in cold conditions. Blood vessels may become irritated and spastic, causing the fingers (and especially the fingertips) to feel cold and painful. Over time (the syndrome typically takes between 6 months and 6 years of frequent exposure to develop) the attacks of pain, blanching and numbness usually become more frequent, although often they subside during warmer weather.
Symptoms of HAVS may also include loss of feeling in the hand and fingers, a progressive decrease in hand strength, reduced dexterity, and arm muscles that tire easily.
In the most severe cases, individuals may experience atrophy of the muscles in the hand, and even gangrene.
Treatment usually consists primarily of reducing work exposure to vibration. Perhaps half of affected individuals experience a return to near baseline within 5 years after the elimination or sharp reduction of exposure. As the syndrome advances, however, often from the time that blanching of the fingers appear, the nerve damage may become irreversible.
Thus, prompt detection, and reducing or eliminating the exposure, is critical.
While, surprisingly, HAVS is not addressed by a specific OSHA standard, it may be addressed under OSHA’s General Duty Clause, which requires each employer to provide a safe and healthful workplace.
Compliance with acceleration levels and exposure duration guidelines established by the American Conference of Government and Industrial Hygienists is suggested, both as a means to limit your employee’s exposure, as well as a means of demonstrating compliance with the General Duty Clause, should you be cited based on one or more employee’s exposure to vibration.
You need to know the vibration rating of all equipment used by your employees, and to calculate the safe time exposure for each item. Make sure that you know for how long employees can use particular tools, and if you don’t know, you need to inquire of the manufacturer, or get the various tools assessed.
Naturally, you should be discriminating in selecting equipment. Look for low-vibration items, or tools incorporating built-in features that absorb a significant amount of the tool’s vibration. Make sure employees use the correct tool for the job, and consider possible alternative means to accomplish tasks that will reduce employee exposure. It may be possible, also, to alter the job to reduce the grip or pressure necessary.
Frequent breaks should be scheduled to avoid long periods of vibrating tool use, and you should try to minimize the use of vibrating tools in cold weather conditions.
Other practices users of vibrating equipment should be trained to observe include the following:
As PPE is usually the least-preferred control measure, anti-vibration gloves are at best moderately effective. They protect the palm more than the fingers, and are of little use at frequencies lower than 25 Hz. Gloves may actually amplify vibration from low-frequency tools. Damping techniques (e.g., wrapping tool handles in viscoelastic material tape), or using vibration isolators on equipment provide more effective protection. While some prefer the greater tactile “feedback” into the fingertips that fingerless gloves provide (and may cut the fingers of the gloves off, leaving only the palm area covered) that should be forbidden, if the user works with vibrating tools.
HAVS is a debilitating, life-changing affliction, and by the time symptoms become pronounced, they will likely be irreversible. Workers must be trained about vibration hazards, early signs and symptoms of HAVS, and best practices to limit exposure. Indeed, they should be cautioned that it is better to change jobs, rather than permitting HAVS to progress beyond its earliest stages.