There’s much to be concerned about when it comes to the impact and vibration from tools and equipment. Almost all equipment on a jobsite vibrates to some extent — some much more than others. Over time, this exposure can have negative repercussions on the operators.
Thomas McDowell, a research engineer for the National Institute for Occupational Safety and Health (NIOSH), says the damage to a person’s body is primarily dependent on the magnitude of the acceleration; the frequency spectra of the vibration generated by the tool; and the length of worker exposure time. Other important factors include the environment a person is working in, their posture, their physical condition and potentially their genetic background.
If you use tools with higher levels of vibration or impact, over time permanent damage to your hands, arms, back, legs and joints can result. Here’s what you should be aware of, as well as how equipment manufacturers are trying to make their products safer to use.
How our bodies react to vibration
Long-term exposure to hand-transmitted vibration from using powered hand tools can lead to a disorder known as hand-arm vibration syndrome. David Rempel, a professor of occupational medicine at the University of California, San Francisco, and professor of engineering at UC Berkeley, is doing research on the effects of impact and vibration to hands and arms. He says these effects cause damage to capillary blood vessels and nerves, which can be serious and irreversible.
Prolonged vibration causes the inner lining endothelial cells to multiply and not function correctly, causing blood to leak through vessel walls. In addition, Kristine Krajnak, leader of the Biological Assessment of Mechanical Exposures team for NIOSH, says their studies show exposure to vibration can result in edema, inflammation and vascular dysfunction. These changes eventually lead to a thickening of blood vessel walls, vascular constriction and a reduction in blood flow.
Nerve damage also results from prolonged exposure to vibration. Rempel says the myelin sheath surrounding nerves gets destroyed, exposing the nerve. (Think of a nerve as an electrical wire and the myelin sheath as the plastic insulation surrounding it.) Nerve fibers also retract, disconnecting from the muscle fiber they activate, resulting in permanent damage.
Although the focus is on hands and arms, your whole body is affected by exposure to vibration and impact. It travels through the limbs to the rest of your body. Joint, neck and back problems can develop when tendons, ligaments, bone and cartilage are damaged.
Mitch Burdick, product manager for concrete tools at Bosch Tools, says regulations and guidelines for establishing vibration limits for power tools come from Europe. “There are no current regulations for tool manufacturing or use limitations in the U.S.,” he points out. Tool companies serving both markets manufacture their products to meet European standards, so U.S. contractors benefit from European requirements.
The European Committee for Standardization (Comité Européen de Normalisation or CEN) is the organization that establishes frequency and time-weighted action and exposure limit values for hand-arm vibrations and whole-body vibrations on the basis of a standardized eight-hour work day. The International Organization for Standardization (ISO) sets the guidelines for the tool manufacturers that test their tools according to established protocols and publish the vibration acceleration values of their tools (expressed in meters per second squared).
In the U.S., there are two voluntary consensus standards: the American National Standards Institute (ANSI) voluntary consensus standard (ANSI S2.70-2006), and the American Conference of Governmental Hygienists standard. These standards established Hand Arm Vibration and Whole Body Vibration Threshold Limit Values. These guidelines recommend methods for the measurement, data analysis, vibration and health risk assessments, and the reporting of human exposures to hand-transmitted vibration.