Understanding the Effects of Power Tool Vibration

Work-related exposure to tools that vibrate can cause fingers to feel numb and tingly. This is a phenomenon which affects the blood vessels, nerves, muscles and joints of the hand, wrist and arm. Extended exposure to mechanical vibration can cause a condition known as Raynaud’s phenomenon, which is sometimes referred to as “white fingers” or “dead fingers.”

It is most commonly triggered by continuous use of hand-held tools and equipment that vibrate. Tools associated with this phenomenon include chainsaws, jackhammers, concrete saws, drills and air chisels, to name a few. Tools that vibrate at low frequencies often cause more damage than those that operate at higher frequencies.

Raynaud’s phenomenon occurs mainly in the fingers of the hand(s) gripping the tool. Vibration restricts the blood supply to the hand(s) and fingers, which, depending on the vibration level and duration of exposure, can contribute to an injury.

Cold or emotional stress is often a contributing factor, but “dead fingers” can occur in warm weather too. In fact, on occasion, I have noticed it while using my chainsaw or while riding my motorcycle in the spring.
Vibration-induced injury starts with the occasional numbness or loss of color in the fingertips. As the injury progresses, the hand(s) and fingers develop a tingling sensation and begin to feel spongy. If exposure is not eliminated, more frequent and persistent symptoms begin to affect a larger area of the fingers and result in the reduction of feeling and manual dexterity in the worker’s hand(s).

Although Raynaud’s phenomenon is not life threatening, severe cases can cause disability, result in worker’s compensation claims and result in workers having to change jobs or stop working. Therefore, it is important that workers know the signs and symptoms of Raynaud’s phenomenon and the workplace tools and equipment that can cause it so action can be taken to limit the exposure.

Typical attacks occur when a person is cold, emotionally upset or when using tools or equipment that vibrates repeatedly or for long periods of time. Symptoms usually include:

• Tingling and slight loss of feeling or numbness in the fingers
• Whitening of the fingers
• Blue skin that feels cold and numb
• Numb, prickly feeling or stinging pain in fingers
• Color changes in the skin from white to blue to red

Raynaud’s phenomenon can gradually get worse if the worker remains exposed to the tools or equipment that caused the problem. As the disorder gets worse, the attacks become stronger and more frequent. Therefore, it is important for the worker to recognize the signs and symptoms and report them to management so action can be taken to fix or eliminate the problem.

Vibration Control
Several factors increase the amount of employee exposure to vibration. The following are some of the factors:

• Poorly designed power tools: Even new tools can expose employees to excessive vibration if they are not designed with devices that dampen or shield the worker from vibrations.
• Poor tool maintenance: Tools that are not properly maintained tend to develop worn or loose parts, which tends to increase vibration.
• Old power tools: Older tools were not equipped with vibration-dampening devices, and many have worn or loose parts.
• Cold hands: Instruct workers to wear gloves and to keep their hands warm when working with vibrating tools.

General controls to reduce vibration:

Use good quality, low vibration tools. Purchase tools that use vibration dampeners or shields to isolate the source of vibration from the employee. Many chainsaws, jackhammers and other tools are now available with dampening devices.

Inspect and maintain power tools on a regular basis. A proper tool inspection is more than looking for a damaged electric cord. Train workers or individuals responsible for inspecting tools about what to look for. Remove defective or improperly maintained tools from service until they can be repaired or properly disposed of.

Wear gloves when using tools that vibrate. A good pair of gloves or gloves with vibration dampening capability built in will absorb some of the energy, but they can also reduce grip strength by as much as 20 percent.

Implement administrative controls to limit exposure duration. Rotate employee job assignments where possible so the same person is not always using the chainsaw and/or jackhammer.

Provide training so workers understand the nature of the hazard, how to control or limit exposure and the signs and symptoms of exposure. Tell workers to report any symptoms and follow up with an evaluation of the tool and the situation.

The construction industry could not function without power tools, many of which do vibrate. However, the fact still remains that if we know and understand the potential hazard we can control or limit the exposure and avoid injury. Almost every job requires the use of vibrating hand tools, but there is usually a simple, inexpensive solution that can reduce the risk of injury.

George Kennedy is NUCA Vice President of Safety.