- Vibration is the mechanical oscillation of a solid body.
- Possible sources of local and general vibration must be identified.
- If necessary, personal protective equipment or other measures to reduce vibration must be used.
Local vibration is caused by the acute vibration of the tool handle or workpiece, which is transmitted to the hand and arm. A worker whose hands are repeatedly exposed to vibrations transmitted through the hand and arm in excess of the limit values over a long period of time may develop damage to the tissues of the hand and arm (localised vibration syndrome). Health risks from local vibration affect people working in many industries and professions. With good management, vibration hazards can be controlled, risks can be reduced and work can be made more efficient.
General vibration is the vibration transmitted to the worker's body. The general vibration in the body primarily affects the weight-bearing parts of the body, the support and musculoskeletal system. The first symptoms are often back pain (for work performed while sitting) or knee pain (for work performed while standing). With prolonged exposure, such pain becomes chronic. In addition, general vibration also affects the internal organs and the body's internal regulation, causing high blood pressure, imbalances or even stomach ulcers.
If working outdoors cannot be avoided, machines with heated handles can be used. When working indoors, the temperature of the workplace should be such that the worker feels comfortable without special clothing. Machines that cause the hands to freeze, such as machines with a steel body or pneumatic tools that direct exhaust air onto the operator's hands, should be avoided. As cold increases the risk of local vibration, the worker is provided with suitable warm clothing and gloves.
If the employee is exposed to vibration (both local and general vibration) in their work, the employer must refer the employee to medical examination with an occupational health doctor.
LOCAL VIBRATION RISK MANAGEMENT
Government of the Republic Regulation No. 109 of 12 April 2007 ‘Occupational Health and Safety Requirements for Vibration-Affected Work Environment, Vibration Limits for Work Environment and Procedure for Measuring Vibration’ establishes the action value of daily vibration exposure, above which the employer is required to manage the local vibration risks of its employees. Workers must not be exposed to vibrations above the exposure limit value, but damage may occur even if exposure values are lower than the action value.
To manage the risks, the employer must have an effective strategy to reduce local vibration. Effective management is often based on a combination of different methods.
Various tools can be used to reduce the effects of vibration when designing a workplace. Jigs and vibration-damping handles are one option. Improper selection of handles can also increase the actual vibration of the hand, so the equipment recommended by the tool manufacturer should be used. Rubber or other elastic material can be wrapped around the handle to improve ease of use. Reducing the gripping or thrusting force of the hand reduces the vibration to the tool user's hand and arm. These forces are applied to support the tool or workpiece, to guide or control the machine, or to achieve a high processing speed. In some cases, the correct position of the operator's hands when holding tools will help prevent excessive exposure to vibration.
Vibration-damping gloves must bear the CE marking, which indicates that the gloves have been tested in accordance with the requirements of EN ISO 10819. Gloves do not significantly reduce the risk at frequencies below 150 Hz (9000 rpm). This means that for most power tools, reducing the magnitude of frequency-corrected vibration with vibration-damping gloves is negligible. Vibration-damping gloves may reduce the risk of vibration to some extent with high-speed or high-frequency vibration tools that do not require high gripping force.
Regular maintenance of power tools and other tools will help keep vibration and shock to a minimum.
The equipment manufacturer should inform the employer of the training requirements and could provide training to the operators. Workers should be advised to allow the tool to rest on the workpiece or support as often as possible and to hold it with a light but firm grip.