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
Vibration
Civil construction workers can be exposed to vibration from a variety of sources including operating trucks, excavators and bobcats, vibrating needles, compacting plates, jackhammers and other pneumatic tools. 1
The two main types of vibration that can lead to musculoskeletal injuries are 1 :
- whole body vibration
- hand/arm vibration.
Example of Injury Mechanisms
The following example illustrates how injury occurs when the load applied to the musculoskeletal tissues is greater than the capacity of the tissues to withstand the force. In this diagram, the load on the tissues rises and falls with each vibration or cycle of a repetitive task. Although this load is below the capacity of the tissues initially, over time the mechanical properties of the tissues can change, resulting in an injury if the task is continued without allowing time for rest and recovery. 1
Statutory Provisions Governing the Prevention of Vibration
On 25 June 2002, the EU adopted Directive 2002/44/EC covering the protection of employees against vibration. The objective of the directive was to set out minimum provisions to protect employees against hazards arising from the use of vibrating equipment. The directive was to be transposed at national level by 6 July 2005; its requirements were to be at least as strict as those of existing national provisions.
Council Directive 89/391/EEC on the introduction of measures to encourage improvements in the safety and health of workers at work is of great importance in the control of vibration risks. It defines general principles on the prevention and elimination of occupational risks, the informing, consultation and participation of workers and their representatives and general guidelines for the implementation of those principles. General employers' and workers' obligations are covered in this directive, which can
be applied directly to the prevention of vibration risks in the construction sector.
Content of the EU Vibration Directive
Employers are now obliged to identify and assess hazards relating to vibration exposure. The vibration directive contains provisions concerning exposure action and exposure limit values. Violation of these values obliges the employer to launch technical, organisational and personal protective measures in accordance with current good practice. Employees must be informed of any risk identification and assessment, and of subsequent protective measures taken. They have to also receive corresponding instruction. Employees exposed to vibration must receive health checks.
Exposure Action and Exposure Limit Values
Daily exposure action and exposure limit values are defined for vibration hazards. These values are standardised against a reference duration of eight hours. For hand-arm vibration, the exposure action value is 2.5 m/s2 and the exposure limit value 5.0 m/s2. For whole-body vibration, the daily exposure action value, standardised for an eight-hour period, is 0.5 m/s2 or 9.1 m/s1.75, the daily exposure limit value 1.15 m/s2 or 21 m/s1.75.
Obligations on the Construction Site
The employer is obliged to conduct a risk identification and assessment study at workplaces where vibration is a hazard. The results must be documented. Should the exposure action values be exceeded, the employer must take measures to reduce vibration. The following must be considered in the process: alternative work procedures; suitable work equipment; personal protective and supplementary equipment; maintenance programmes for equipment and systems; workplace design; information on the proper use of vibrating machines; limiting the duration of exposure; appropriate shift schedules with breaks; and suitable clothing for protection against cold and damp.
Under no circumstances should the exposure limit value be exceeded. But, if it is exceeded, the employer is obliged to take immediate measures to reduce exposure below the limit value.
Employees at risk of exposure to vibration must be informed of the results of the risk assessment and be instructed in the use of the protective measures subsequently provided. Should the exposure action limit be exceeded, employees are entitled to an occupational medical examination. The purpose of the examination is the prevention and early diagnosis of vibration-induced health disorders.
For work on temporary or mobile construction sites, Council Directive 92/57/EEC defines the obligations of the client, project supervisor, employer and of the coordinators for safety and health matters, during the project preparation and execution stages. The client or project supervisor must put in place a safety and health plan before setting up on the site.
The prevention of vibration risks must be taken into account by the project supervisor from the start of the project preparation stage when the various stages of work are planned. The safety and health coordinators must draw up a safety and health plan taking into account the activities on the site, including specific measures to prevent the risks associated with vibration.
Duration of Exposure
The degree of exposure can be determined by measurement or by an estimate based on the manufacturer's data, and by observation of the working procedures concerned. The duration of exposure should include only the time during which the employee is in contact with the vibrating surface. Interruptions and breaks should not be included in exposure times. Manufacturers are obliged to declare whole-body vibration values exceeding 0.5 m/s2 and hand-arm vibration values exceeding 2.5 m/s2 in the user instructions.
Should an assessment of the exposure to hand-arm vibration consider the manufacturer's values, the standardised conditions under which they are measured must be compared to those actually arising under working conditions on site. Should these conditions differ, or should the vibration not be measured on the handle or the axis of measurement not correspond to the axis of the maximum vibration value, the manufacturer's value should be
doubled as a precaution. Vibration values relevant to the conditions in the specific application may be requested from the manufacturer.
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
