NIOSH Publication : A Guide to Selecting Non-Powered Hand Tools: 2004-164

About This Booklet:

The purpose of this booklet is to help you select or purchase the best available ergonomically designed non-powered hand tool. The information and the hand tool checklist are based on peer reviewed articles and expert input. The checklist has been evaluated for reliability in identifying the presence or absence of basic ergonomic design features (Dababneh et al.*). The right tool will help you reduce your risk of injury, such as carpal tunnel syndrome, tendonitis, or muscle strain.

*Dababneh A, Lowe B, Krieg E, Kong Y, and Waters T, A Checklist for the Ergonomic Evaluation of Non-Powered Hand Tools, accepted for publication in the December 2004 issue of the Journal of Occupational and Environmental Hygiene.

Note: This booklet covers most ergonomic features that should be considered when selecting or purchasing hand tools, but does not cover all features. Specifically, it does not address tool weight, tool balance, vibration or tool maintenance.

No one is required to use the information in this booklet. This booklet is not intended to provide employers with information on how to comply with Cal/OSHA regulations.

Foreward

Non-powered hand tools are widely used in a variety of industries including construction, manufacturing, and agriculture. National data suggests that a large number of injuries known as musculoskeletal disorders are attributable to hand tool use in occupational settings, resulting in unnecessary suffering, lost workdays, and economic costs. Prevention of work-related musculoskeletal disorders is a high priority for both the National Institute for Occupational Safety and Health (NIOSH) and the California Occupational Safety and Health Administration (Cal/OSHA). Both agencies recognize the importance of design and selection of hand tools in strategies to reduce injuries of this type.

To the untrained eye, however, it may be difficult to evaluate tools from an ergonomic point of view. The purpose of this document is to demystify the process and help employers and workers identify non-powered hand tools that are less likely to cause injury--those that can be used effectively with less force, less repeated movement, and less awkward positioning of the body. Presented here are the ergonomic basics of hand tool use. These principles are meant to complement the ordinary process of deciding on what tool to select by knowing how it is used and the task to which it will be applied.

The reasonable and common-sense approaches outlined in this document can be directly applied to challenges like these:

This document also contains an easy-to-use checklist for comparing tools against several design characteristics that have been shown to reduce physical stresses on the user. We hope this checklist and the accompanying background material will be of practical use to all who wish to select tools that get the job done more safely, comfortably, and productively.

Is this an Ergonomic hand tool?

You be the judge ...

Some tools are advertised as "ergonomic" or are designed with ergonomic features. A tool becomes "ergonomic" only when it fits the task you are performing, and it fits your hand without causing awkward postures, harmful contact pressures, or other safety and health risks. If you use a tool that does not fit your hand or use the tool in a way it was not intended, you might develop an injury, such as carpal tunnel syndrome, tendonitis, or muscle strain. These injuries do not happen because of a single event, such as a fall. Instead, they result from repetitive movements that are performed over time or for a long period of time, which may result in damage to muscles, tendons, nerves, ligaments, joints, cartilage, spinal discs, or blood vessels.

Definitions

How do you know if you have a problem?

These symptoms may not appear immediately because they develop over weeks, months, or years. By then, the damage may be serious. Take action before you notice any symptoms.

A. Know your job (pg. 4).
B. Look at your work space (pg. 6).
C. Improve your work posture (pg. 7).
D. Review the "Tips for Selecting Hand Tools" (pg. 8) and then Select the Tool (pgs. 13,14).

Use the Checklist on pages 13 and 14 to select the best tool. The features listed on the Checklist correspond to the tips found on pages 8 to 11, "Tips for Selecting Hand Tools."

A. Know Your Job

Before you select a tool, think about the job you will be doing. Tools are designed for specific purposes. Using a tool for something other than its intended purpose often damages the tool and could cause you pain, discomfort, or injury. You reduce your chances of being injured when you select a tool that fits the job you will be doing.

The list of tools in each category shows a few examples of tools that are most frequently used.

Next, consider whether you need the tool to provide power or precision. Then select the tool with the correct handle diameter or grip span.

B. Look At Your Work Space

Now look at your work space. Awkward postures may cause you to use more force. Select a tool that can be used within the space available. For example, if you work in a cramped area and high force is required, select a tool that is held with a power grip. A pinch grip will produce much less power than a power grip. Exerting force with a pinch grip means you will work harder to get the job done.

If you work in a cramped space, you may not be able to use a long-handle tool. Use of a long-handle tool may cause awkward postures or harmful contact pressure on your hand as you use more force. Instead, use a tool that fits within the work space. A short-handle tool can help you reach your target directly as you keep your wrist straight.

C. Improve Your Work Posture

Awkward postures make more demands on your body. In some cases, the placement of the work piece will affect your shoulder, elbow, wrist, hand, or back posture. Whenever possible, choose a tool that requires the least continuous force and can be used without awkward postures. The right tool will help you to minimize pain and fatigue by keeping your neck, shoulders, and back relaxed and your arms at your sides.

For example, avoid raising your shoulders and elbows. Relaxed shoulders and elbows are more comfortable and will make it easier to drive downward force.

D. Select The Tool

Over time, exposure to awkward postures or harmful contact pressures can contribute to an injury. You can reduce your risk of injury if you select hand tools that fit your hand and the job you are doing.

Tips for Selecting Hand Tools

Tools used for power require high force. Tools used for precision or accuracy require low force

1. Closed grip span Open grip span For single-handle tools used for power tasks: Select a tool that feels comfortable with a handle diameter in the range of 1 1/4 inches to 2 inches. You can increase the diameter by adding a sleeve to the handle.

2. For single-handle tools used for precision tasks: Select a tool with a handle diameter of 1/4 inch to 1/2 inch.

3. For double-handle tools (plier-like) used for power tasks: Select a tool with a grip span that is at least 2 inches when fully closed and no more than 3 1/2 inches when fully open. When continuous force is required, consider using a clamp, a grip, or locking pliers.

4. For double-handle tools (plier-like) used for precision tasks: Select a tool with a grip span that is not less than 1 inch when fully closed and no more than 3 inches when fully open.

5. For double-handled pinching, gripping, or cutting tools: Select a tool with handles that are spring-loaded to return the handles to the open position.

7. Select a tool that is coated with soft material. Adding a sleeve to the tool handle pads the surface but also increases the diameter or the grip span of the handle (see 1, 2, 3, or 4 above).

Tools with bent handles are better than those with straight handles when the force is applied horizontally (in the same direction as your straight forearm and wrist).

Tools with straight handles are better than those with bent handles when the force is applied vertically.

10. For tasks requiring high force: Select a tool with a handle length longer than the widest part of your hand – usually 4 inches to 6 inches.

Prevent contact pressure by making sure the end of the handle does not press on the nerves and blood vessels in the palm of your hand.

11. Select a tool that has a non-slip surface for a better grip. Adding a sleeve to the tool improves the surface texture of the handle. To prevent tool slippage within the sleeve, make sure that the sleeve fits snugly during use.

American Industrial Hygiene Association, "An Ergonomics Guide to Hand Tools", p. 18
Dababneh A, Lowe B, Krieg E, Kong Y, and Waters T, A Checklist for the Ergonomic Evaluation of Non-
Powered Hand Tools, accepted for publication in the December 2004 issue of the Journal of Occupational and Environmental Hygiene.
Eastman Kodak Company, "Ergonomic Design for People at Work", Vol. 2, p. 350
Eastman Kodak Company, "Ergonomic Design for People at Work", Vol. 1, p. 146
Kodak’s Ergonomics Design for People at Work, 2nd Edition, p. 349

Acknowledgements

Writers, Editors and Photographers

Checklist

Use BOTH sides of the checklist to compare similar tools. For example, if you have two pliers and want to select the best of the two, compare each tool against the features on the checklist.

COMPLETE BOTH SIDES

Dababneh A, Lowe B, Krieg E, Kong Y, and Waters T, A Checklist for the Ergonomic Evaluation of Non-Powered Hand Tools, accepted for publication in the December 2004 issue of the Journal of Occupational and Environmental Hygiene.

This booklet is a joint effort between the California Occupational Safety and Health Administration (Cal/OSHA) and the National Institute for Occupational Safety and Health (NIOSH), Centers for Disease Control and Prevention (CDC).