Vibration Surveys and Assessments
The Control of Vibration at Work Regulations 2005 establish a means of preventing employees' exposure to two classes of vibration - Hand Arm Vibration and Whole Body Vibration - which are defined as follows:- "hand-arm vibration" means mechanical vibration which is transmitted into the hands and arms during a work activity;
- "whole-body vibration" means mechanical vibration which is transmitted into the body, when seated or standing, through the supporting surface, during a work activity.
- Identification of operations with the potential to expose personnel to vibration
- Measurement of vibration levels on vibrating plant/equipment
- Assessment of the likely level of exposure to HAV/WBV for all persons exposed
- Illustration of methods for the continual assessment of HAV exposure in-house
- Advice on how to reduce HAV/WBV exposure
Hand-Arm Vibration
The primary cause of hand-arm vibration injury is work which involves repeated holding of vibrating tools or workpieces. Where a risk assessment identifies hazardous jobs, a preventative programme should be introduced to control, so far as is reasonably practicable, any risk of vibration injury to employees.
When considering the potential risks posed by vibrating tools, it is necessary to take into account both the vibration level(s) and exposure time(s) during the shift, which together contribute to the overall daily personal exposure. This is denoted as the A(8) level and is presented in units of acceleration. This is the 8-hour energy average vibration exposure which is equivalent to that received from all the tools used during the shift.
It is essential to distinguish between exposure time and usage time. The latter is taken to be the overall time required to complete a task requiring the use of vibratory equipment. The task time would include periods in which tools are not used, such as preparation, marking up etc. Exposure time (also sometimes referred to as "trigger time" or "anger time") is the total time for which the equipment is transmitting vibration to the user's hands. It is usually considerably less than the usage time.
Hand-transmitted vibration is expressed in terms of the acceleration of the equipment in contact with the hand. The figure given is normally given in metres per second squared (m/s²), e.g. 2.8m/s². An employee's daily vibration exposure depends upon the size of this figure as well as the length of time that the employee is exposed to the vibration.
The Regulations require employers to:- Reduce exposure to a minimum;
- Provide information and training;>/li>
- Assess exposure levels;
- Carry out a programme of measures to reduce exposure and provide appropriate health surveillance when exposure reaches the A(8) exposure ACTION value of 2.5m/s2 and to;
- Keep exposure below the A(8) exposure LIMIT value of 5m/s2.
The Control of Vibration at Work Regulations 2005 establishes two levels for employees' daily exposure to whole body vibration:
- the daily exposure limit value is 1.15 m/s2 A(8);
- the daily exposure action value is 0.5 m/s2 A(8).
If the A(8) action value is exceeded, control measures would be required, including reducing exposure to a level that is as low as reasonably practicable, providing employees with appropriate information, instruction and training and "consideration of:
- other working methods which eliminate or reduce exposure to vibration;
- choice of work equipment of appropriate ergonomic design which, taking account of the work to be done, produces the least possible vibration;
- the provision of auxiliary equipment which reduces the risk of injuries caused by vibration;
- appropriate maintenance programmes for work equipment, the workplace and workplace systems;
- the design and layout of workplaces, work stations and rest facilities;
- suitable and sufficient information and training for employees, such that work equipment may be used correctly and safely, in order to minimise their exposure to vibration;
- limitation of the duration and magnitude of exposure to vibration;
- appropriate work schedules with adequate rest periods; and
- the provision of clothing to protect employees from cold and damp."
