Information on this page is drawn from "Prevention of vibration risks in the construction sector" published by European Agency for Safety and Health at Work
Hand-arm Vibration
On hand-held or manually guided machines, hand-arm vibration is transmitted through the handles or surface of the workpiece, via the palms and the fingers, into the hands and arms. Examples of machines that may cause hand-arm vibration are demolition hammers, drills, hammer drills, angle grinders, chain saws and hand-held circular saws.
Exposure to hand/arm vibration occurs when working with air-operated, pneumatic, electric, or petrol powered tools. Exposure to hand/arm vibration primarily damages vascular and nerve tissue, typically of the hand and fingers. Prolonged exposure can eventually result in a disease known as Raynaud's syndrome or Vibration White Finger. 1
When the body or limbs are exposed to vibration, the force of this movement is absorbed by the body's skin and the musculoskeletal system. Intermittent exposure to vibration may allow sufficient time for the soft tissues to recover between periods of exposure. However, long duration or frequent vibration exposure will significantly increase the risk of musculoskeletal injury. 1
Examples of exposure to hand/arm vibration 1
Operating petrol-powered jack hammer
Operating plate compactors
The Potential Health Effects of Hand-arm Vibration
Employees who are regularly exposed to this kind of vibration may suffer from hand-arm vibration syndrome, which causes neurological and motor disorders in the hands and fingers, as well as circulatory disorders in the fingers and disorders of the musculoskeletal system.
Vascular disorders may occur in the form of white finger, which is caused by inadequate circulation. This phenomenon is generally more prevalent in colder seasons. Depending upon the duration and intensity of the exposure to vibration, it may affect only the fingertips or the entire fingers. Neurological disorders are experienced as tingling and numbness in the fingers, which become increasingly severe with rising exposure. Examples of musculoskeletal disorders related to hand-arm vibration includes wrist tendinitis and tenosynovitis.
Hand - Arm Vibration Checklist
This information was drawn from material produced by Cal-OSHA. The original pdf is available at the bottom of the page. 6/1/09
This checklist can be used to determine whether a work-area is safe with regards to Hand - Arm Vibration.
Checklist
Hazard Identification
- The company has a written Injury and Illness Prevention Program (IIPP) that meets all Cal/OSHA requirements. It includes identification of vibration hazards on the site, regular inspections, accident investigation, and correction of hazardous conditions.
- All tools that may pose a vibration hazard have been identified.
- Workers are encouraged to report tools that are causing particular problems.
Medical Monitoring
- Health monitoring is provided for workers exposed to vibration. It includes pre-employment and annual exams.
- Health monitoring is conducted by a qualified health provider who is fully aware of the signs and symptoms of hand-arm vibration syndrome (HAVS). The health provider receives detailed information regarding the worker's exposure to vibration.
- Any worker who develops prolonged signs and symptoms of handarm vibration syndrome is removed from further exposure to vibration. Anyone removed retains all earnings and seniority.
Worker Training
- Workers who use vibrating tools are trained in the effects of vibration and methods for reducing exposure.
- Training includes information on factors that increase vibration induced health risks (including cold, noise, and smoking).
Tool Design, Inspection, and Maintenance
- Non-vibrating tools are used instead of vibrating tools whenever possible.
- Tools with vibration-reducing features are purchased and used whenever possible.
- Tool suppliers are asked to provide evidence that their equipment reduces vibration.
- Vibrating tools are equipped with grips made of heavy rubber or similar vibration-damping material. Tools are inspected daily before use and are kept clean.
- Tools are well maintained. They are kept sharp, lubricated, and tuned. (Tools that are worn, out of alignment, or otherwise in poor condition can produce greater vibration.)
- Damaged, defective, or worn tools are tagged and removed from service until repaired.
Breaks
- The number of hours in a day, and the number of days in a week, that a worker uses vibrating tools is kept to a minimum.
- Operators of vibrating tools take a 10-minute break each hour and/or alternate work with vibrating and non-vibrating tools.
Work Practices
- Workers use only tools with which they have experience, or on which they have been trained.
- Operators "let the tool do the work" by using the smallest amount of grip force possible (while still maintaining control of the tool).
Personal Protective Equipment
- If necessary, personal protective equipment (PPE) is provided by the company and worn by workers. The types used are appropriate for the work and give adequate protection.
- Workers using tools always wear safety glasses with side shields or other eye/face protection. Eye and face protection meets the requirements of American National Standards Institute (ANSI) Z 87.1 1989, American National Standard Practice for Occupational and Educational Eye and Face Protection.
- Gloves and adequate cold weather clothing are worn when necessary. (Cold contributes to hand-arm vibration syndrome.)
- Gloves have vibration-damping material in palms and fingers. They fit properly and don't increase the grip force required to control the tool.
- Workers exposed to foot injuries from crushing or penetrating actions, hot surfaces, falling objects, or hazardous substances, or who are required to work in abnormally wet locations, use appropriate foot protection such as steel-toed safety shoes and/or boots. (For jackhammers, workers wear a steel covering over the whole foot, not just the toes.)
- Workers exposed to noise in excess of 90 dB use hearing protection. (Noise contributes to hand-arm vibration syndrome.)
CAL/OSHA ERGONOMICS REGULATION
- If there has been more than one ergonomic injury within a year to workers doing the same task, the company has set up a program to identify and correct these hazards and provide relevant training.
Download the pdf file for the checklist
Reduction of Hand-arm Vibration
Replacing the current work procedure with an alternative that generates lower vibration should always be examined. Equipment should always be suitable for the task concerned and of adequate performance if the duration of exposure for the employee is to be kept as low as possible.
Anti-vibration handles
One possibility for reducing hand-arm vibration lies in the use of vibration reducing padded handles. Such handles are decoupled as far as possible from the source of vibration, i.e. the machine. Depending upon the manufacturer of the machine, the decoupling mechanism may take the form of springs, dampers, or systems that balance the vibration. Where handles are retrofitted, it is crucial that the manufacturer's information is followed because incorrect handles may even increase vibration.
Autobalancers
Some machines, such as angle grinders, are equipped with autobalancers, which compensate for unbalanced masses. This is achieved by loose steel balls arranged within a container on the rotating shaft. Should an imbalance arise, the balls automatically align to counteract it and, to some extent, cancel it out. Vibration can also be reduced by using anti-vibration handles.
Mass Balancing
Jigsaws and reciprocating saws are available on the market that employ the principle of mass balancing and thus run very smoothly, therefore also generating low vibration.
Suitable Tool Attachments
The selection of suitable tool attachments also has an influence upon vibration exposure. Attention should be paid to the concentricity and possible unbalanced masses of grinding wheels. Blunt saw blades should be replaced or sharpened in good time. The material and geometry of drill bits may influence the reduction of vibration.
Reduction of Grip and Feed Forces
If the grip and feed forces acting upon the hand while using the machine are reduced, so too is the vibration exposure. Means should therefore be considered for modifying work processes so that contact between the employee and the vibrating machine is reduced or prevented. This may, for example, be achieved by the use of stands or stays during drilling in ceilings and walls. Remote-control trench compactors are available for civil
engineering use. Users of these compactors are not exposed to vibration at all.
Anti-vibration Gloves
Anti-vibration gloves may lessen high-frequency vibration. Wearing gloves may, however, also increase the grip forces and thus to some degree negate the protective action. A list of approved anti-vibration gloves can be purchased, for example, from the BG Institute for Occupational Safety (BGIA) at www.bgia-handbuchdigital.de/450110.
References
1 Information in this section is drawn from "Participative ergonomics in civil construction handbook" published by Queensland Government
For More Information
The KARLA catalogue of representative noise and vibration data at the workplace (in German) may serve as an aid for estimating exposure to hand-arm and whole-body vibration. Further support for estimating exposure and calculators for hand-arm and whole-body vibration can be found at http://www.hse.gov.uk in English. Parameter calculators in German can be found on the BGIA's web pages at http://www.hvbg.de and at
http://www.bg-metall.de/index.php?id=180
