1. Reducing Hand-Arm Vibration

2. You Will Learn:
What Hand-Arm Vibration (HAV) is and how it can hurt you
Sources of Hand-Arm Vibration
Current methods for controlling and reducing exposure to hand-arm vibration

3. Where is it? Found in electric, pneumatic or gas driven tools
Industries:
Construction
Logging
Equipment and machinery repair
Ship Yards
Automobile manufacturing and repair
Building and maintenance of roads and railways
Foundries
Mines and quarries
Plate and sheet metal manufacturing
Public Services and public utilities

4. What is Hand-Arm Vibration?
Hand-Arm Vibration is the transfer of vibration from a tool to a worker’s hand and arm.
The amount of HAV is related to the acceleration level of the tool when grasped by the worker and in use. The vibration is typically measured at the handle of the tool while in use to determine the acceleration levels transferred to the worker.
Acceleration - the rate of change of velocity in speed or direction per unit time (e.g., per second)
…another way of putting it is the speed at which the vibrating surface goes back and forth…

5. Measuring Vibration
Acceleration is measured in hertz (hz) or meters per second.
A vibration level below 3.5 m2 is a safe vibration level for an 8 hour exposure to hand arm vibration.
As vibration numbers go up, the duration of safe exposure decreases.

6. Tools Moderate vibration High vibration impact wrenches
carpet strippers
chain saws
percussive tools
jack hammers
scalers
riveting or chipping hammers
grinders
sanders
jig saws

7. Tools
Power tools can transmit vibration to the hands and arms, and this has a number of effects on the body. If you’re exposed to enough vibration, it can cause damage to the nerves and blood vessels in your hands and arms. Vibration also tends to make the muscles tighten up. The tighter you grip the tool, the more vibration gets transmitted to your hands and arms, and this makes injury more likely.

8. Tools
Some tools put out a high level of vibration, and this can start to have these effects on your body in as little as half an hour of use per day. Among them are:
Concrete breakers and road drills
Hammer drills
Nut Runners
Pedestal Grinders
Power hammers and chisels
Riveting hammers and bolsters
Brush cutters

9. Symptoms Associated with HAV
Tingling or numbness in the fingers or toes
Blanching (whitening due to lack of circulation) of fingers. Recovery from blanching attacks is accompanied by acute pain and flushing.
Reduced sensitivity to pain, touch and temperature
In later stages, hands become numb and fingers appear blue/black. Gangrene is possible.

10. Disorders Associated with HAV
Vibration White Finger (VWF)
Damage to blood vessels from vibration causes vessels to collapse, preventing oxygen to reach tissues. It is often made worse by cold.
Raynaud’s Disease
A disease in which people who may be pre-disposed develop symptoms similar to those of VWF, only vibration and cold may or may not play a part.

11. Prevention
Development of HAV is dose related, meaning that effective control procedures should be:
reducing the intensity of the vibration
reducing the duration of the exposure to vibration
early recognition of signs and symptoms
identifying vibration sensitive individuals
Dose means the amount of exposure to vibration measured either in units of time, or intensity of vibration
Reducing the time would be to reduce the actual time per work day the person was exposed to the vibration. The effects of vibration are cumulative, so frequent breaks would not be a way to reduce time exposure.
Reducing the intensity of the vibration would be done by dampening the vibration by using anti-vibration gloves, taping the grip with a foam tape, or purchasing tools with lower vibration levels.
Encouraging employees to report the symptoms associated with vibration exposure early can both serve to limit the severity of a vibration induced injury and to help identify vibration sensitive individuals

12. Buy lower vibration tools
Controls
Buy lower vibration tools
Tape existing handles with vibration dampening tape
A link to the European Hand Arm Vibration Database is in the Links and References at the end of this presentation
Use full fingered anti-vibration gloves
Regularly maintain and balance hand tools
Suspend tools from tool balancers to reduce hand grip force

13. Monitor Exposure
Monitoring exposure can be as simple as applying a simple questionnaire on a regular basis (weekly or monthly) which addresses signs and symptoms to those who regularly use vibrating hand tools.
Another method would be to monitor the exposure of the worker directly. However this is much more time consuming.
It is important to understand that people often over estimate the length of their exposure to vibration. They may report the total time they were doing the job which may differ significantly from the time they were actually applying the tool to the task(s) involved.
Some experts suggest that the monitoring of exposure is better assessed by someone other than the worker doing the job.

14. Actions That Can Help Wrapping handles with visco-elastic tape
Using full fingered anti-vibration gloves
Replacing tool gaskets with nitrile vibration reducing gaskets
Suspend tools from tool balancers to reduce grip force

15. Work Practice Guide:
Use only ergonomically designed anti-vibration tools
Be trained on the proper method for using the tools
Use only anti-vibration full-finger protected gloves
Use tool wraps, but for only short periods of time
Grasp the tool as lightly as possible, consistent with safe work practices
Rest the tool on a support as much as possible or use with overhead balancers

16. Work Practice Guide:
Operate tools only when necessary and at reduced speeds if possible
Avoid continuous exposure by using rest breaks
Avoid using worn out, unbalanced tools which probably have higher vibration levels
Keep the hands and entire body warm and dry
Avoid smoking because nicotine enhances the ability of blood vessels to go into spasm
Seek medical attention immediately if finger tingling or numbness or finger blanching is experienced

17. Isolation and Damping
Isolation alters the pathways between the machine and the person, by reducing the vibration arriving at the person.
Example: shock absorber on a car.
Damping is a method of converting vibration into a small amount of heat. The vibration is absorbed by the gloves or tape and heat is generated from the dampened motion.
Example: anti-vibration gloves, or taping the handles of vibrating tools.
Many new tools are being designed to separate the motor from the grip, and some separate the grip from the point of operation

18. Powered Hand Tools
Isolation point
motor
Point of operation
grip

19. Purchasing Hand Tools Purchase hand tools which are
ergonomically designed:
Lower weight
Lighter weight battery
Tool grip:
keps the wrist straight
correct size for the user (1 ¼” to 2”)
dampened with rubber, foam, or tape
isolated from the motor
better

20. Links & References Links References Hand-Arm Vibration Calculator
Hand-Arm Vibration Database
Health Risks from Hand-Arm Vibration Advice for Employers
Vibration isolation example
References
Hand-Arm Vibration – A Comprehensive Guide for Occupational Health Professionals P.L. Palmear, MD, FFOM, and D.E. Wasserman, MSEE,MBA OEM Press Second Edition, 1998 ISBN: