As someone who owns or works with power or pneumatic tools, you probably don’t give much thought to how they affect your body. You should, though, because these tools vibrate and shock your body every time you use them. Because of the long-term effects of using these tools, here are some things you must be aware of:
How our bodies handle vibration
The National Institute for Occupational Safety and Health (NIOSH) has conducted years of research on how tools affect a person’s health. Dr. Kristine Krajnak, leader of the Biological Assessment of Mechanical Exposures Team for NIOSH, says tools with vibration levels are typically measured in meters per second squared, but for specific reasons, NIOSH measures frequency in hertz.
Frequencies above 60 hertz affect both nerves and blood vessels, especially in hands and arms. “The damage to the vascular system is more pronounced when working at temperatures below 40 degrees Fahrenheit,” Krajnak says.
Physical damage results over time—the more you use a tool, the more likely you are to incur an injury to blood vessels and nerves. Tool vibrations more than 60 hertz are particularly damaging to the joints, tendons and ligaments of the hands and arms, and to the neck and head as well.
For smaller blood vessels and capillaries, damage resulting from excessive exposure to vibration begins with the injury to the cells lining blood vessels. These cells send chemical signals to the muscle cells that make up the outer portion of blood vessels and cause them to constrict the blood vessel, thereby reducing blood flow.
Over time, the muscle wall grows thicker, reducing the area through which blood can flow. This reduction in blood flow causes fingers and hands to have a whitish appearance and feel cold, similar to Raynaud’s disease.
Nerve damage resulting from excessive exposure to vibration occurs with the gradual loss of its myelin sheath, a fatty white insulating layer surrounding nerve cells that allow them to conduct electrical signals more quickly (think of the plastic insulation covering around copper wires).
Myelin sheath loss starts at the nerve endings in the skin. As this happens, the nerve also begins to retract. Before there is significant damage, workers often experience a feeling of tingling and numbness. With continued use, workers can lose sensation in their fingers and hands and also display a reduction in grip force and the ability to control a power tool.
The International Organization for Standardization (ISO) is the world’s largest developer of voluntary standards. Krajnak says ISO 5349-1&2 are the standards that address the risk of developing a vibration-related injury, depending upon the length and frequency of use and the magnitude emitted by the tool.
Tool manufacturers are aware of the problem and are working to update their technology to produce tools that vibrate less and have handles that absorb more vibration and shock.
Europe is ahead of the U.S. in terms of making information about tool vibration levels and suggested rest intervals easily available. Some U.S. manufacturers, however, publish the vibration levels of their tools on their websites and in printed materials.
Information and awareness is essential—few contractors and workers know about the risks of working with vibrating tools. The responsibility to be proactive falls on you, because by the time symptoms appear, it may be too late to do anything about them.
Krajnak says not all people are affected the same way; only about half of those who are exposed end up with “white finger” or related issues, so there are other factors that aren’t yet understood. Still, the numbers of affected workers are significant.
Tools with frequencies above 60 hertz include chipping hammers, jackhammers, nail guns and impact wrenches. Those operating below 60 hertz include drills, impact drivers, grinders, circular saws and recip saws.
Suggestions for using tools
– Don’t use power tools when your limbs are cold; keep them warm.
– Buy tools that advertise vibration limitation systems (balanced shafts, gears and other internal components) and absorbing handles.
– Look for lightweight and ergonomic (easily held without a strong grip) tools.
– For large tools such as vibratory compactors, choose products that offer remote operation.
– Wear vibration-absorbing gloves that can help reduce the amount of vibration to your hands.
Joe Nasvik is a writer and editor serving the construction and concrete industries. He has 18 years’ experience as a concrete contractor. Contact him at firstname.lastname@example.org.
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