Vibration Exposure of Heavy Goods Vehicle Drivers
Vibration is the swift movement back and forth. Workers can be exposed to hand-arm vibration (HAV) and or whole-body vibration (WBV) by the use of work equipment and processes that transmit vibration into the hands and arms of employees. WBV is caused by vibration transmitted through the seat or the feet by workplace machines and vehicles. Long term, regular exposure to high levels of WBV can cause serious health problems such as lower back pain. HGV drivers investigated in this research drive for long distances which can expose these workers to high levels of vibration. It is essential that these workers are provided with a workplace which does not affect their safety, health or welfare as Heavy Goods Vehicles are the place of work for most of the driver’s working day. This investigation reveals the level of vibration that these workers are exposed to highlighting the health effects they may be at risk to. (*NOT FINISHED*)
2.0 Literature Review
This section will detail the relevant legislation regarding whole-body vibration and the significant research that has been done in the area of whole-body vibration at work. The literature review opens with an interesting summary of what vibration is as it is essential that the reader understands this.
2.1 What is vibration?
Tim South gave a good outline of what vibration is and how it occurs in his book ‘Managing Noise and Vibration at Work’. Vibration occurs when a body oscillates repeatedly around an equilibrium position. The simplest form of vibration can be shown when a small mass is hung from a spring. The mass will come to rest at the position where the gravitational force acting on it is equal in size (but opposite in direction) to the force exerted by the stretched spring (See ). Displace the mass slightly from that position (either up or down) and the forces are no longer in balance. If the spring is pushed slightly downwards and then released, then the spring is stretched more than before and the force it exerts is then greater than the gravitational force. An upwards force exists and the mass will accelerate upwards. Eventually it reaches the equilibrium position again but it is now moving and it is only when it has passed the equilibrium position that a downwards force will exist which can start to slow the mass down. Eventually it comes to a halt. It is now above its equilibrium position and the gravitational force exceeds that exerted by the spring. The mass will be accelerated downwards. It will continue to move upwards and downwards about the equilibrium position until an external force acts to change this motion. This sort of motion is known as simple harmonic motion (SHM). It is a very simple model for what happens in real systems. Even a simple system of real mass and real spring does not always behave exactly like this. The mass may start to rotate slightly as well as moving up and down. Nevertheless, it can be applied to a great number of real systems in order to begin to understand what is happening when real objects vibrate. The vibration will have a frequency. This is a number of complete oscillations that occur in one second and as with sound the unit it is measured in is the hertz. The mass and spring are likely to have rather a low vibration frequency – probably no more than 1 Hz. Most vibrating bodies will vibrate at higher frequencies than this, maybe up to hundreds or even thousands of hertz. Overall vibration affecting human beings tends to have a frequency range which is lower than the range of frequencies concerned with audible noise. Although they overlap, vibrations of interest for their health effects commonly have a frequency range from 1 Hz up to 1,000 Hz.
It is tempting to see vibration as essentially static, while noise manifestation of a travelling wave. This is too simplistic as vibrations can certainly travel. If this was not the case then a vibrating mechanism inside a tool would have no way of causing the vibration energy to be transferred to the human body. With sound, standing waves can be established in an enclosed space, so that the theoretical differences between sound and vibration are not particularly great. In practice, waves travel much faster in solids than in air. The motion of vibration in workplace situations is not normally apparent and it is reasonable to treat vibration for most of the time as though it were a static phenomenon.
2.2 The Health and Safety Authority
The Health and Safety Authority (HSA) is a state-sponsored body with the overall responsibility to ensure the health and safety at every type of workplace in the public and private sectors in Ireland. It reports to the Minister for Enterprise, Trade and Innovation and was established under the Safety, Health and Welfare at Work Act 2005. They work with employers, employees, individuals, trade union organisations and other organisations to secure the health and safety at work. They also monitor compliance of workplaces with legislation and take enforcement action on those that are of non-compliance. They can issue an employer with an improvement direction (direction to submit an improvement plan in the case of an activity presenting a risk to the safety, health or welfare of persons), improvement notice (where the employer is in breach of health and safety legislation or fails to submit an improvement plan), prohibition notice (where there is a serious personal risk of injury to any person). They give advice and guidance to employers, employees and self-employed on all matters of health and safety. In order to assist with compliance of the legislation relating to vibration at work, the HSA has published guidelines on the Regulations which will be discussed later in this dissertation. They also encourage education, training and research in health and safety.
2.3 ISO 2631: Mechanical vibration and shock – Evaluation of human exposure to whole-body vibration.
The international standard on the assessment of whole-body vibration is ISO 2631: 1997. Part 1 deals with direct health effects and Part 4 deals with the effects of vibration on train passengers and crews. The current UK equivalent is British Standard(BS) 6841: 1987. Vibration effects are likely to vary greatly between less- and more- sensitive individuals. ISO 2631 establishes levels that typical individuals can feel a vibration, find it uncomfortable or adverse effects can be predicted. Where fine manipulation is required it can be dangerous for an employee exposed to vibration to be unable to use controls accurately. When considering the effect on vision, a similar concern is the ability to read information from displays accurately. It has been reported that vibration can effect internal organs such as digestive and reproductive systems but the link is not well established. ISO 2631 does not attempt to predict the likelihood of these effects if they exist. According to this standard, the most important health effect is the link to spinal injury, which is also controversial. While this sort of injury is not usually denied that it can be caused by WBV exposure, the relative importance of WBV and other agents has not clearly been determined.
Most WBV exposure involves other potential hazards such as prolonged periods sitting in poorly designed seats, which is a common cause of back injury. In some cases vibration exposure and poor posture go together. Drivers may be exposed to relatively high WBV, but they also frequently have unsuitable seats, and poor posture due to other tasks they perform. Whole-body vibration exposure in the workplace is usually associated with driving or being carried in vehicles.
The assessment of whole-body vibration is essentially a complicated subject, and this is reflected in the complexity of the standard. Based on the orientation of the human body, three axes are measured; (1) the x-axis (back-to-front direction) (2) the y-axis (from side-to-side) and (3) the z-axis (from feet to head) (See ). ISO 2631 defines six frequency weightings to be used in different circumstances. They are designated Wc, Wd, We, Wf, Wj and Wk. Most assessments can be carried out using just two of them: Wd for the x- and y-axes and Wk for the z-axis. Wf, which is defined over a range of lower frequencies than other weightings, is used for assessing the likelihood of vibration exposure causing travel sickness. ISO 2631 specifies another number of multiplying factors to be applied to the vibration magnitude when it has been measured using the appropriate frequency weighting (See ). For workplace exposure assessments concerned with the possible health effects, values measured along the horizontal axes (x and y) must be multiplied by a factor of 1.4. While measurements on the vertical axis (z) are multiplied by a factor of 1 i.e. do not need to be multiplied by anything. The type of time averaging to use when assessing WBV exposure has been the subject of considerable research. The simplest approach is to use the equal energy principle, using an rms average should be evaluated over a standard 8hr assessment period. The quantity which is used to assess daily exposure using this technique is the equivalent 8hr continuous exposure abbreviated A(8) in HAV assessments. The equivalent 8hr exposure can be calculated from the measurement data covering shorter, portions of the day.
However, research has shown that this equal energy averaging underestimates the effect of high vibration magnitudes as compared to extended periods of exposure. To take account of fully of these high vibration magnitudes, root-mean-quad or rmq averaging can be used. This technique is similar to the rms averaging used with hand-arm vibration, except that the fourth power of the acceleration is averaged and it is the forth root of this average which is used to represent the equivalent continuous level. If the vibration magnitude is doubled, then a quartering of the exposure period would tend to underestimate the human response.
The vibration dose value (VDV) is a quantity which can be measured with equipment which uses this forth-power integration. VDV values cannot be compared numerically to A(8) values. A VDV for an entire day’s work can be calculated from a VDV measured during a shorter period of time.
where: ‘VDVpart’ is the VDV measured over a representative period ‘t’. ‘T’ is the length of the full shift. The unit of VDV is measured in ‘metres seconds to the minus 1.75’ i.e. ms-1.75 or m/s1.75.
2.4 Study of over travel of seat suspensions
A research report prepared by Stayner for the Health and Safety Executive gives an excellent overview of a literature review done on Whole-body vibration (HSE 2001). The extended review sets out two fundamentals for assessing the findings of research into health effects of whole-body vibration:
Comparison with criteria used to assess the health effects of other, similar environmental stressors (noise and hand-transmitted vibration)
Comparison of whole-body vibration with other stressors that have been associated with low back disorders, namely posture (including prolonged sitting), and manual handling (lifting, pulling, pushing).
The literature was then reviewed in two main sections: historical overview and an assessment of evidence published. From the historical overview it appears that whole-body vibration was originally suggested by medical practitioners as a likely cause of back trouble when this was first observed among operators of new types of machine and vehicle. By 1970, this suggestion appeared to have been accepted with little question and with little effort to compare vibration with other possible causes of back complaints. A measurement of vibration magnitudes was not feasible before 1970 and for a number of years after that it was a separate activity from studies of occupational health. Even now, there are only a few studies to suggest a clear distinction between effects of vibration having different magnitudes. There is also only one study in which both vibration and postural stress have been compared on a similar numerical basis. Historically, there have also been attempts to understand the mechanism whereby vibration and other stresses, can lead to degeneration of elements of the lower back. These have indicated that cycles of relatively high magnitude acceleration are probably more important than the lower levels of vibration that often contribute more to the time-averaged measures of exposure defined in ISO 2631. The review of occupations shows that in general the evidence does associate occupations with elevated risks of disorders, but does not distinguish between vibration and the other stressors as contributors to that risk. What are often claimed to be vibration studies are usually occupation studies. A number of general patient studies also reviewed show that the incidence of low back disorders among a general population is high (between 30% and 60%) and differences between occupational groups are small. Specific studies of occupational groups, carefully controlled, are suggested to be needed to show significant effects. The ten groups reviewed are operators or drivers of: agricultural tractors; earthmoving and construction machines; industrial (fork-lift) trucks; helicopters; transport “tugs”; overhead cranes; rail and subway vehicles; military vehicles; road vehicles; and standing operators of concrete plant. A summary of the likely causes for elevated risk of low back disorders in the various occupations follows. In this, it is suggested that continuous vibration is unlikely to be a serious contributor to damage. In most occupations, posture is likely to be a significant factor, and probably the main factor for pilots of helicopters and operators of overhead cranes. In some occupations, such as farming, manual handling has in the past been an important factor that has generally been overlooked. Also those occupations in which, dynamic loading is significant, it is the peaks of occasional transient vibrations or shocks that are most likely to contribute to any damage. It is suggested that guidelines for compensation should not involve vibration requirements, but should specify only the diagnosable physiological damage and a history of occupational use of any of a prescribed list of machines or vehicles. It is further suggested that the method, developed by ISO/TC108/SC4/WG10 for evaluating repeated shocks, should also be tested as a possible measure for more continuous vibration. This is supported by a short dissertation on aspects of measurement, in particular the trade-off between magnitude and duration of exposure, and the importance or otherwise of frequency weighting. It is suggested that future research should be targeted at two aspects of the subject. First, health studies should be integrated with more specific evaluation of subjects’ exposures to vibration and shock, with measurements made in such a way as to enable alternatives to rms or VDV to be extracted, in particular the method of ISO/TC108/SC4/WG10, or some equivalent count of “fatigue cycles”. Secondly, a more integrated approach to research into low back disorders should aim to find a common method for rating the severity of postural and manual handling loads as well as shock and vibration. A particularly useful outcome would be a set of methods for assessing occupational exposures to the combined stresses. In the meantime, more effort should be devoted to assessing all three groups of stresses in relation to any future health studies.
And exposure magnitudes and histories should be more closely linked with individual subjects whose health is under research. There appears to be little value in trying to correlate cause and effect from questionnaire surveys. In conclusion: the report summarises that vibration has not been shown to be the main cause of lumbar syndrome in those occupations in which it is known to be a significant health risk. There has been a shortfall in the available vibration exposure data for association with the health data. There is also a lack of a relevant method for quantifying postural stress in field studies to provide a similar association with health data. There is a lack of data on any measure other than frequency weighted rms acceleration and specifically to test the hypothesis of a fatigue mechanism. There is insufficient data even to suggest a possible relationship between reducing vibration magnitude and reducing the incidence of back problems.
2.5 The 2002 Physical Agents (Vibration) Directive
The Physical Agents (Vibration) Directive establishes the exposure action value and an exposure limit value. For whole body vibration, the Directive states that each quantity can be evaluated either in terms of an equivalent continuous 8hr exposure or in terms of a vibration dose value. The exposure action value is an equivalent 8hr exposure of 0.5ms-1 or a vibration dose value of 9.1ms-1.75. The exposure limit value is an equivalent 8hr continuous exposure of 1.15ms-2 or a vibration dose value of 21ms-1.75. Member states were free to use either the VDV values or the equivalent 8hr values when framing their domestic legislation. Ireland chose the 8hr reference period defined in the General Application Regulations 2007 while UK also chose the 8hr values in the Control of Vibration at Work 2005. The duties on the employers at the action/limit levels under the Physical Agents (Vibration) Directive are listed in . These values have been criticised for being too low, but there is not yet sufficient scientific evidence to support the establishment of precise exposure limits. Under this Directive, it is the duty of employers to carry out risk assessment of the risks to any employee whose work is likely to expose them to whole body vibration. They must decide which employees are exposed (e.g. an employee who drives vehicles for extended periods of time as part of their job). They should then collect data on whole body vibration exposure on the particular vehicle. Information about the normal and exceptional work cycles can be collected by interviewing the subject and department managers. It is not usual to combine the data from three axes, however a procedure exists in ISO 8041: 2005 for calculating a combined value. This Directive adopts the normal practice of making a separate assessment of the vibration component along each of the measured axes. The values (along the x- and y-axes) must be multiplied by 1.4.
When the assessment value has been compare to the action and limit values, the employer’s duties can be determined in relation to each group of exposed employees. For whole-body vibration, either the A(8) value or the VDV for each axis, after multiplication by 1.4 in the case of the horizontal axis, is compared with the exposure action and limit values. The relevant employer duties apply whether the action or limit value is exceeded for just one axis or for all three axes.
2.6 A Review of long term vibration dose for vehicle operators
A research paper discusses the long term vibration dose for truck drivers (Atkinson, Robb & Mansfield 2002). Details of the first set of measurements carried out on three articulated heavy goods vehicles are given. Initial analyses showed extremely high magnitudes of vibration exposure on the seats of the vehicles. However on closer inspection of the data suggested that peaks corresponded to times when the driver sat on the seat pad and when the driver left the seat. The high vibration exposures were a piece of the long-term recording process. Suggested methods of filtering data to remove this were used to provide corrected vibration exposures for the drivers of the three trucks. Long term exposure to whole-body vibration was measured in three trucks. The vibration exposures are close to the action level in the Physical Agent (Vibration) Directive. Analysis of the exposure data highlighted practical problems with autonomous or semi-autonomous vibration recording. Particularly, when peaks in the vibration can occur due to the driver sitting or leaving the seat. These measurements can dominate the total vibration exposure and this paper measures should be taken to minimise their influence on the measurement of vibration so that ‘true’ vibration exposures can be collected. Such techniques are suggested such as to post process the data to remove measures which are considered unlikely or to include other technologies to eliminate times when the seat is not occupied. Overall this paper highlights the practical problems with autonomous or semi-autonomous vibration recording.
2.7 Evaluation of transmissibility of WBV exposures from the floor to the seat
Previous research suggested that seats may not be properly matched to equipment resulting in amplified exposure to whole-body vibration (WBV). A study on the evaluation of the transmissibility of WBV exposure from the floor to the seat was carried out on 33 scrapers in the construction (Cann et al. 2003). Tri-axial accelerometers and a Biometrics™ data logger were used to measure the vibration at both the seat and floor. Data collection and analysis compiled with the 1997 ISO 2631 standards. The measurement period lasted until the operators completed three work cycles. The mean seat effective amplitude transmissibility (SEAT) factors were calculated in accordance with the 1992 ISO 10326 standards for each vehicle. Results indicated that on average the seats reduce the level of exposure by 4% (mean SEAT values of 0.96). However, the dampened values all exceed the ISO 2631 guidelines for the health caution zone. On average only a 4% reduction in the levels of WBV dose from the floor to the seat was found in the study. The seats in earlier models of (621B) scarpers actually amplified the vibration doses. Small reductions in dose at the seat in comparison with the floor were seen in the newer models, a fact that also corresponded to decreases in the dominant frequencies from 3.15 Hz to 2.5Hz. Despite the small reductions in transmissibility of the seats, the vibration doses and exposures still exceeded the ISO 2631 health caution zones. Therefore, more research needs to be done to improve seat designs. This is especially true in terms of multi-directional dampening, since most studies to date have only addressed the vertical access.
2.8 Safety, Health and Welfare at Work Act 2005
The main piece of legislation relating to health and safety at work in Ireland is the Safety, Health and Welfare at Work Act of 2005 and came into force on 1st September 2005. The Safety, Health and Welfare at Work Act 2005 replaced the Safety, Health and Welfare at Work Act 1989. This Act details the responsibilities of employers, the self-employed, employees and various other parties in relation to safety and health at work. The Act also outlines the functions of the Health and Safety Authority. It aims to include the management of safety and health at work into all other management functions within a business. It is a very detailed document which was set out by the Irish Government and the Health and Safety Authority including 89 Sections and 7 Specific Schedules. The following sections are those that apply or are likely to be applied to vibration at work.
2.8.1 General duties of the employer
Under Section 8 of this Act, every employer is required to exercise all due care to ensure they have the protective and preventative measures in place to protect the health, safety and welfare of their workers.
Every employer must (without financial cost to the employee):
manage and conduct work activities.
design, provide and maintain a safe workplace, safe means of access to and egress from the workplace.
ensure prevention of exposure to any substance or item that could pose a risk on any persons at work e.g. vibration or noise.
provide safe system of work i.e. plan activity, identify hazards and controls associated with the activity and ensure signature of responsible person.
provide sufficient instruction, training and supervision.
prepare risk assessments.
provide and maintain adequate personal protective equipment where risks cannot be avoided.
Under Section 9 employers must provide employees with information in a manner and language that can be understood by the employees. The information must include:
Hazards and risks within the workplace and measures taken to control the risk affecting those employees. Information should be given to permanent/temporary employees on any specific increased risks associated with their work, health surveillance necessary and any specific qualifications or skills required for the job.
Safety representatives and selected competent persons must be informed of detail on risk assessments, reportable accidents and information arising from the application of protective measures.
2.8.2 General duties of employee
Employees have a number of duties under Section 13 of the Safety, Health and Welfare at Work Act 2005. Employees must:
comply with health and safety legislation.
take care to protect his or her own safety, health and welfare.
co-operate with employer or other persons to support the compliance of health and safety legislation.
attend or undergo any training for a certain task that the employer or any Regulations may require.
correctly use any machine, equipment, article or personal protective equipment that they are provided with and (under Section 14 of this Act) not interfere or misuse with anything they are provided with to protect their safety, health and welfare.
2.9 EU Good practice guidance on WBV
This non-binding "guide to good practice" (Griffin et al. 2006) facilitates the assessment of risks from exposure to whole-body vibration, the identification of controls to eliminate or reduce exposure and the introduction of systems to prevent the development and progression of injury. This guide on whole-body vibration has been prepared under contract VC/2004/0341 for the European Commission Directorate General Employment, Social Affairs and Equal Opportunities. It gives very comprehensive advice with the view of implementing the Directive 2002/44/EC on the minimum health and safety requirements regarding the exposure to risks from vibrations and should be essential reading for employers identifying measures to prevent risk from vibration. Basically the guide comes in two parts, one dealing with hand-arm vibration and the other with whole-body vibration. Both parts deal with practical issues, such as risk assessment, determining exposure duration, vibration magnitude, exposure, substitution, equipment selection, training, information and maintenance. The guide includes useful references to EN standards.
2.10 Safety, Health and Welfare at Work (General Application) Regulations 2007
The Safety, Health and Welfare at Work (General Application) Regulations 2007 came into operation on 1 November 2007 and replaced Safety, Health and Welfare at Work (General Application) Regulations 1993 (except for Part 10 relating to accident reporting) and the Safety, Health and Welfare at Work (General Application Amendment) Regulations 2001 (Work Equipment Regulations). The following are the Regulations that are relevant or likely to be relevant to vibration n the workplace.
2.10.1 Control of Vibration at Work
Chapter 2 of Part 5 and Schedule 6 to the 2007 Regulations revoke the Safety, Health and Welfare at Work (Control of Vibration at Work) Regulations 2006. Regulations 133 to 142 of the 2007 General Application Regulations, transposes the provisions of Council Directive 2002/44/EC into Irish law. They state the minimum health and safety requirements for employees exposed to vibration at the workplace by setting down measures to protect them from the risks arising from any such vibrations. Regulation 136 outlines that where employees are exposed or are likely to be exposed to vibration, an employer must carry out a risk assessment to assess and, if necessary they must measure the levels of mechanical vibration to which the employees are exposed to. The assessment and measurement of this mechanical vibration must be carried out in accordance with Schedule 6 to the 2007 Regulations. Where mechanical vibration poses a risk to employees, the employer under Regulation 140 must provide them or their safety representative with “suitable and sufficient with information, instruction and training”. Regulation 141 requires the employer to make available appropriate health surveillance to employees for whom a risk assessment shows a risk to their safety and health. Such a risk may arise where an employee is exposed to mechanical vibration in excess of an exposure action value. The exposure limit values and action values for HAV and WBV are set down in Regulation 135of the 2007 Regulations. For whole-body vibration the daily exposure limit value is 1.15m/s2and the daily exposure action value is 0.5m/s2.
2.11 Reduction of WBV exposure
The HSE gives clear guidance to employers on reducing whole body vibration in a published information sheet (HSE 2009). They suggest that the action needed varies with the degree of risk. If the work does not reach the EAV or only exceeds it occasionally, precautionary measures should be ensured that exposure is as low as reasonably practicable. If the exposure is often above the EAV then changes must be made to working practices to reduce exposure to vibration. The time spent doing the task must be limited if actions has been taken but exposures are still likely to exceed the ELV. The information sheet outlines clear measures and controls to reduce the risk of WBV in the agricultural area but the HSE also published a leaflet on the control of the back-pain risks from WBV to help employers manage the risk of back pain (HSE 2005). It outlines the reasons for back pain in drivers as follows:
poor design of controls make it difficult for the driver to operate the vehicle easily or to see properly without twisting or stretching;
incorrect adjustment by the driver of the seat position and hand and foot controls making it necessary to continually twist, bend, lend and stretch to operate vehicle;
sitting for long periods of time without being able to change position;
poor driver posture;
repeated manual handling and lifting of loads by the driver;
excessive exposure to WBV particularly to shocks and jolts;
repeatedly climbing into or jumping down from a high a high cab or one which is difficult to get in and out of.
The risk increases where the employee is exposed to two or more of these factors together.
This leaflet also states that the risk for road transport drivers from vibration exposure is likely to be low unless the vehicles do not have effective suspension or are driven over poor surfaces or off-road. However there may be other causes of back pain for road transport drivers such as poor posture, long periods in the same position and repeated lifting and carrying.
It gives clear guidance for employers in order to comply with the regulations that are previously discussed in this report. It details advice on how to carry out a risk assessment which is required by the regulations.
The actions for controlling the risks in this leaflet include:
Training and instruction on: adjusting the driver weight setting on their suspension seats to minimise vibration and to avoid the seat suspension ‘bottoming out’ when travelling over rough ground; adjusting the seat position and controls correctly, where adjustable, to provide good lines of sight, adequate support and ease of reach for foot and hand controls; adjusting the vehicle speed to suit the ground conditions to avoid excessive bumping and jolting; steering, braking, accelerating, shifting gears smoothly. Training and Information is dealt with in more detail in the leaflet.
Select vehicles and machines with the appropriate size, power and capacity for the work and the ground conditions and consult your trade association for advice.
Maintain vehicle suspension systems correctly (e.g. cab, tyre pressures, seat suspension).
Obtain appropriate advice (from seat manufacturers, machine manufacturers and/or vibration specialists) when replacing a vehicle seat. Seats need to be carefully matched to the vehicle to avoid making vibration exposure worse.
Introduce work schedules to avoid long periods of exposure in a single day and allow for breaks where possible.
Avoid high levels of vibration and/or prolonged exposure for older employees, people with back problems, young people and pregnant women.
Carry out health monitoring (which is dealt with in detail in the leaflet).
The leaflet recommends that advice be sought from suppliers on those machines and vehicles that are most suitable and with the lowest vibration, for the work you plan to do. It also discourages the use of any machines or vehicles reported to have unusually high vibration. Choosing unsuitable machines or vehicles could increase vibration exposure as well as being less efficient.
2.12 The costs of Vibration Exposure
Tim South discusses the costs of vibration exposure in his book ‘Managing Noise and Vibration’. Measures taken to control vibration exposure are often expensive but the failure to control risks can be very costly too. The problem is that the costs of taking action to reduce risks are likely to be immediate, obvious and easily quantifiable while the possible costs of failing to take action are more distant, less certain and less clearly attributable to one particular failure. In the longer term things can be much less clear. It is possible that if no action is taken that a number of employees could develop WBV symptoms. They are likely to take more time off sick and in some cases eventually be unable to remain in the job. A few years down the line, a compensation claim may arise from employees. Compensation would be covered by the company’s insurers but the insurance company may take action in response to the claim such as changing working practices, increasing premiums or refusing to renew cover. Also the HSA or HSE alike may prosecute on inspection or require immediate changes to working practice. None of these costs are inevitable and none of them are easy to quantify. The employees exposed may be slow to develop symptoms or they may suffer after they have left their current employment.
From this information, it is not surprising that health and safety professionals are usually keen to invest in safer working arrangements; however it is also not surprising that they sometimes struggle to make their case. When managing risks of vibration exposure it is essential that the various control measures available are identified to assess their effectiveness and probable cost. Various courses of action can be proposed such as a combination of engineering controls, management procedures and medical surveillance.
Although it is a legal requirement to carry insurance for third party compensation claims, there are many costs involved in defending claims such as time spent assessing records, making documents available and briefing lawyers which are not usually covered by the policy. The time potential loss of business following a claim which gains publicity and training of replacements for skilled and experienced workers who have to retire or move to other work are examples of costs which are less easy to attribute to the cause. The cost of arranging the insurance cover is also an uninsured cost. Insurance premiums are determined on the basis of the insurance company’s perception of the risks to which employees are exposed to. It is normal for insurers to arrange periodic health and safety inspections. If such an inspection reveals a potential problem with vibration exposure, then the insurer may insist on a specific risk assessment of vibration risks and remedial action if cover is to be continued or renewed.
A Discussion paper on ‘Back pain: its management and costs to society’ provided by the Centre for Health Economics, University of York discusses the estimated social costs of back pain in the UK and assesses the effectiveness of increasing management of back pain on the reduction of these costs. 50% - 80% of the UK population suffers from back pain at some stage of their life. Repeated episodes are very common although 90% of back pain problems improve within six weeks, with or without treatment. Back pain and its management remains a problem despite many research papers discussing the topic over the past three decades. Although only 15% of cases can be diagnosed, this paper focuses on the majority which are due to mechanical low back pain. Due to the scarcity of data it is only possible to make crude estimates of the costs of back pain to the National Health Service in the UK. These costs probably lie between £265 million and £383 million (approx. €306 and €443 million to date). Most of these costs are generated in General Practice due to the large number of consultations and Hospital in-patient management due to the high treatment cost per person. Between 1986 and 1992 claims for back pain alone increased in the UK by about 104%. The indefinable costs of back pain and disability affecting the individual are likely to be considerable. After about six months, when the problem has become chronic, the individual’s function and social activities may become severely affected. The General Practitioner is the key worker for back pain patients and recent data suggests that these account for between 5.8 to 8.6 million consultations each year. Most consultations are associated with a prescription for medication and advice to rest. The processes are not well understood and treatment therefore is usually palliative. There is some evidence of the usefulness of spinal manipulation, exercise and patient education to reduce back pain disability. However more research is needed to clarify which interventions are most effective for which category of problem. In the UK, careful review is required as the use of 900,000 hospital bed days each year for back pain patients. Hospitalisation is not only expensive, but also in combination with prolonged bed rest and excessive investigations may be harmful, unless surgery is required.
This report identifies the following risk factors for back pain; manual handling, static postures, vibration exposure and smoking. Both physical and psychosocial factors in the workplace have been linked with back pain. A number of studies have indicated that both primary and secondary prevention of back pain and injuries in the workplace can be cost effective, but this research is incomplete. Once the back pain has become chronic, more aggressive rehabilitation programmes appear to be the most effective way of returning individuals to their previous occupation. The goal of this paper is to reduce the disability that may result from mechanical lower back pain by appropriate management. Reviews of the literature have suggested the more effective approaches to managing low back pain, but these need to be translated into practice to ensure that resources are used effectively.
2.13 A possible link to prostate cancer
A journal article poses the question: could whole-body vibration play a role in prostate cancer (Young, Kreiger, Purdham & Sass-Kortsak 2009). It summarises the literature on the risks of prostate cancer in whole-body vibration related occupations and conducted a meta-analysis. The results obtained from this study indicated that occupational exposure to WBV cannot be ruled out as a possible risk factor for the disease. However, other studies involved driving occupations with exposure to other risk factors for prostate cancer. Thus, further epidemiological studies are needed to better understand this associated.
Up to one in four European workers is exposed to vibration, according to a report published by the European Agency for Safety and Health at Work. The report ‘Workplace Exposure to Vibration in Europe: an expert view’ found that between 5% and 25% of workers are exposed to whole body vibration (WBV) and between 5% and 11% are exposed to hand arm vibration (HAV). Citing figures from the Dublin-based European Foundation for the Improvement of Living and Working Conditions, the report says that exposed workers are predominantly male, with at least 36% exposed to vibration for a quarter of their working time, compared to 10% of female workers. Significant exposure is measured by reference to exposure for at least a quarter of the working period. The industries with the highest levels of exposure are construction, manufacturing and mining, agriculture and fishing, the utilities (electricity/gas/water) and transport and communications, with exposure levels of 63%, 44%, 38%, 34% and 23% respectively. The report, which notes that the Vibration Directive (2002/44/EC) has been adopted as national law in all EU member states, is based on a detailed examination of the situation regarding exposure to vibration in six European countries: Belgium, Germany, Spain, Finland, France and Poland. The report identifies the types of machinery and equipment most likely to breach the exposure limits set by the Directive. In relation to WBV, it is estimated that the action levels will be exceeded by most off-road machinery and agriculture and forestry tractors when travel is frequent.
6.0 Conclusions / Recommendations
The European Agency for Safety and Health at Work (2008) ‘Workplace Exposure to Vibration in Europe: an expert view’ Luxembourg: Office for Official Publications of the European Communities. ISBN 978-92-9191-221-6
Griffin, M.J., Howarth, H.V.C., Pitts, P.M., Fischer, S., Kaulbars, U., Donati, P.M. & Brereton, P.F. Advisory Committee on Safety and Health at Work (2006) ‘Guide to good practice on whole-body vibration: non-binding guide to good practice for implementing Directive 2002/44/EC on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (vibrations)’ Brussels, Belgium, European Commission.
Stayner, R.M. (2001) ‘Whole-body vibration and shock: A literature review’ HSE Books. ISBN 0 7176 2004 2
Cann, A.P., Gillin, E.K., Salmoni, A.W., Vi, P. & Eger, T.R. (2003) ‘Transmissibility of whole-body vibration from floor to seat, experienced by scraper operators in the construction industry’ Nexgen Ergnomics.
Atkinson, S., Robb, M., & Mansfield, N.J. (2002) ‘Long Term Vibration Dose for Truck Drivers – Preliminary Results and Methodological Challanges’ Department of Human Sciences, Loughborough University.
Shannon, G., 2007. Health and Safety Law and Practice. 2nd Edition. Dublin: Round Hall Ltd.
South, T., 2004. Managing Noise and Vibration at Work A practical guide to assessment, measurement and control (pg. 171-173). Elsevier Butterworth Heinemann.
Young, E., Kreiger, N., Purdham, J. & Sass-Kortsak, A. (2009) ‘Prostate cancer and driving occupations: could whole body vibration play a role?’. International Archives of Occupational and Environmental Health, 82 (5): 551-556
Health and Safety Executive (2005) ‘Control back-pain risks from whole-body vibration’. HSE Books, ISBN 0 7176 6119 9.
Health and Safety Executive (2009) ‘Whole body vibration in agriculture’. Information Sheet No. 20. HSE Books,
Moffett, J.K., Richardson, G., Sheldon, T., Maynard, A., 1995. Back pain: its management and costs to society. Centre for Health Economics, the University of York.
British Standards Institute. 1987. BS 6841: 1987 Guide to measurement and evaluation of human exposure to whole-body mechanical vibration and repeated shock. BSI
International Standards Office, 1997. ISO 2631: 1997 Mechanical vibration and shock – Evaluation of human exposure to whole-body vibration. ISO
International Standards Office, 1997. ISO 8041: 2005 Human response to vibration – Measuring instrumentation. ISO
Safety, Health and Welfare at Work Act 2005, No. 10 of 2005, Irish Statute Book. Available from:
http://www.irishstatutebook.ie/2005/en/act/pub/0010/index.html [Accessed 18 Jan 2011]
Safety, Health and Welfare at Work (General Application) Regulations 2007, S.I. No. 299 of 2007, Irish Statute Book. Available from:
http://www.irishstatutebook.ie/2007/en/si/0299.html [Accessed 18 Jan 2011]
Safety, Health and Welfare at Work (Control of Vibration at Work) Regulations 2006, S.I. No. 370 of 2006, Irish Statute Book. Available from:
http://www.irishstatutebook.ie/2006/en/si/0370.html [Accessed 18 Jan 2011]
Directive 2002/44/EC of the European Parliament and of the Council of 25 June 2002 on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (vibration). No.44 of 2002, Eur-Lex. Available from: http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2002:177:0013:01:EN:HTML [Accessed 18 Jan 2011]
The Control of Vibration at Work Regulations 2005, No. 1093 of 2005, legislation.gov.uk. Available from: http://www.legislation.gov.uk/uksi/2005/1093/contents/made [Accessed 19 Jan 2011]
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