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Shaking Up Safety

Published: 27th Jun 2012 in OSA Magazine

havsSome schools of thought advocate wearing gloves to guard employees against Hand Arm Vibration Syndrome (HAVS). Others suggest the protection gloves offer from this condition is minimal. Whatever your counsel has been on this matter, it’s important managers have a comprehensive understanding of this potentially very serious condition in order to safeguard workers health in the long term – whether that’s by supplying their work force with suitable hand protection, or through other means.

Vibration transmitted to the hands and arms by powered handheld and stationary tools is known to cause occupational injuries among workers. Excessive vibration exposure can lead to signs and symptoms of peripheral vascular and peripheral neural disorders of the fingers and hands.

A most notable injury associated with vibration exposure is Hand Arm Vibration Syndrome (HAVS), aka vibration white fingers (VWF) or Raynaud’s phenomenon. In the United States, millions of workers use vibrating handheld tools and are exposed to vibration on a daily basis. In the UK, it is estimated that up to one in ten people who regularly work with vibrating tools may develop this type of disorder.

This article discusses vibration produced by powered handheld and stationary tools in the workplace. It presents serious physiological effects of excessive vibration transmission to the hands and arms. Despite the absence of a US federal regulation, this article presents a strategy proposing a vibration safety programme with a comprehensive approach in managing occupational vibration exposure. This article does not cover Whole Body Vibration.

Vibration overview

Kroemer, Kroemer and Kroemer-Elbert (2001) define vibration as oscillatory (harmonic) motion about a fixed point. Vibration is called periodic when the oscillation repeats itself, and the body continues to vibrate at the same frequency over a considerable period of time. A one-time shock and impact is called a nonperiodic vibration.

Some of the most widely used powered handheld and stationary tools in various industries are impact tools such as chipping hammers, concrete breakers, needle scalers, pneumatic riveting hammers, pneumatic nailers, jack drills and jack hammers. Other examples include nonimpact tools such as chainsaws, pneumatic wrenches, grinders, routers, circular saws, reciprocating saws, jigsaws, pedestal grinders, polishers, powered lawn mowers, powered sanders and brush cutters.

Transmission of vibration to the body

According to the Health and Safety Exectuvive (HSE) 2005, HAV is vibration transmitted from work processes into the worker’s hands and arms. NIOSH states the level of vibration produced by a tool is influenced by:
• Tool type and weight
• Operating speed
• Ergonomics of tool use
• Environmental conditions
• Antivibration materials used

The Royal Society for the Prevention of Accidents (2007) reported the use of power tools is common in both underground and surface mining; construction; forestry; shipbuilding; motor vehicle manufacturing and repair; foundries; public utilities including electric, telecommunications, gas and water; furniture; railways and aircraft manufacturing.

Occupational vibration hazards and injuries

HealthLink (2008) explains that Raynaud’s phenomenon affects the blood vessels in the fingers, toes, ears and nose. It is characterised by episodic attacks causing blood vessels to constrict. Those who suffer from Raynaud’s phenomenon experience severe pain in the arms, wrists and hands. Early symptoms are tingling and numbness in the fingers, which can cause sleep disturbance; inability to feel with the fingers; loss of strength in the hands, which prevents picking up or holding heavy objects; tips of fingers turn white, aka blanching, then blue - and then red and painful on recovery.

Blanching occurs when the small arteries of the fingers contract, thus preventing blood circulation. Kroemer et al discuss the condition called white or dead finger, a vasospasm resulting when arteries reduce their diameter due to vibrations of body members, particularly in the fingers and hands.
MedicineNet (2008) explains the fingers turn blue due to prolonged lack of oxygen. When the blood vessels reopen, there is a local flushing that causes blood flow into the arteries.

The two classifications of Raynaud’s phenomenon are primary and secondary. A person with primary Raynaud’s phenomenon has no underlying disease or associated medical problems. Symptoms and involvements of primary Raynaud’s disease are usually symmetrical; that is, the same areas of both hands are affected.

Secondary Raynaud’s phenomenon is less common but a more complex and serious disorder, as individuals with this disease have an underlying medical condition.

The involvement is usually asymmetrical. Workers who operate vibrating handheld tools and those whose fingers are subjected to repeated stress are vulnerable to this type of disorder. NIOSH (1989) classifies HAVS as a disease under secondary Raynaud’s phenomenon. HAVS is a chronic progressive disorder in the hands and arms with a latency period that may vary from a few months to several years of exposure. The progressive stages of HAVS arise from cumulative effects of vibration induced trauma to the hands from regular, prolonged use of vibrating hand tools. To be diagnosed with HAVS, neurologic symptoms must be persistent and must occur without provocation from immediate exposure to vibration.

It is important to identify signs and symptoms of HAVS at an early stage. If HAVS is allowed to persist under vibration, it can lead to the development of vibration white fingers (VWF) and carpal tunnel syndrome. HAVS can cause serious disability, and once the damage is done, it is permanent. HAVS can cause pain, distress and sleep disturbance; inability to perform fine work, like assembly of small parts or everyday tasks such as buttoning a shirt; reduced ability to work in cold or damp conditions, since it will trigger vasospasm and blanching; and reduce grip strength.

Carpal tunnel syndrome results from repeated compression and entrapment of the median nerve where it passes through the wrist into the hand, aka the carpal tunnel. The median nerve is the main nerve that extends down the arm to the hand and it provides the sense of touch in the thumb, index finger, middle finger and half of the ring finger.

While many workers are potentially at risk of developing HAVS, as discussed, according to the HSE (2005) about 145,000 cases of VWF filed by coal miners were settled in the UK. The estimated settlement costs of VWF claims and the lung disease of coal miners totalled £5.5 billion.

Tropical effects

Earlier studies on HAVS were conducted in Europe and North America: both with cold climates. The 1989 NIOSH study of foundry and shipyard workers observed the direct relationship between years of exposure and severity of vibration syndrome (VWF latency between two to 17 years). This NIOSH study and other studies reported HAVS symptoms including VWF occurring during low temperature conditions, but have not made a proposition that it can promote HAVS.

A study by Suzuki and Itoh (1970) made a correlation between ambient temperature and VWF attacks. They reported that the critical ambient temperature for the provocation of VWF attacks is around 15° C (59° F). Research work by Yu, Yao, Teng, Ho and Chen (1988) described that tropical climate conditions inhibited the occurrence of VWF. This concept was supported by Futatsuka, Inaoka, Ohtsuka, Sakurai, Moji and Igarashi (1995) after conducting a HAVS study in tropical rain forestry workers.

In another study Futatsuka, Shono, Sakakibara and Quan (2005) examined health effects of powered hand tool vibration on quarry workers in the tropical setting of Vietnam, specifically VWF. The authors did not find any clear evidence of VWF in tropical quarry workers because of warmer work climate conditions with average ambient temperature of 25° C (77° F). The study found that five to ten percent of rock drill operators might be suffering from moderate HAVS.

Vibration hazard mitigation

A Vibration Safety Programme addresses recognised risks of HAV. It consists of management commitment; risk assessment; control of vibration; medical surveillance; personnel training; recordkeeping; and programme review and evaluation. Management commitment is demonstrated through an effective programme, approved by the chief executive of the organisation. Designation of roles and responsibilities and allocation of resources greatly signify management commitment. To provide acceptability and ownership, employees and supervisors should be consulted during programme development.

Vibration measurement and risk assessment

Vibration of powered handheld and stationary tools should be measured for initial evaluation and/or for personnel monitoring. In the United Kingdom, HSE presented HAV limits as follows:

• Exposure action value (EAV) at 2.5 m/sec2 for an eight hour average as the daily amount of vibration exposure above which employers are required to control exposure
• The exposure limit value (ELV) at 5.0 m/sec2 for an eight hour average as the maximum amount of vibration an employee may be exposed to daily
A formal risk assessment is performed on tasks that use powered handheld and stationary tools. It should be regularly reviewed and revised when necessary, specifically when there is a change in tools and/or task process. Interview employees and supervisors on any HAVS signs and symptoms and ask about equipment which seems to have high vibration and other ergonomic issues. Make an inventory of vibrating tools and equipment to include the tool make, model, power, vibration risks, and vibration emission value.

vibration risk assesmentRank the task as high risk if it involves regular use of hammer (impact) action tools for more than one hour daily, or rotary and other (non-impact) tools for about four hours daily. A moderate risk task entails regular use of hammer action tools for more than 15 minutes a day, or some rotary and other tools for about one hour daily. HSE reported that tool manufacturers and employer organisations have adopted a colour coding system for tools to be marked as high, medium and low risk.

As an alternative, WISHA Hand Arm Vibration Analysis can be used to assess risks. HSE advocates doubling the vibration value from the equipment handbook in evaluating employee exposure. If using more than one tool, calculate the total vibration exposure value for all tools.

There are quantitative HAV analytical packages for HAV calculation available free for downloading from Thomas E Bernard’s website http://personal.health.usf.edu/tbernard and HSE calculator at http://www.hse.gov.uk/vibration/hav/vibrationcalc.htm.

Vibration control

After determining job tasks with vibration exposure, prioritise addressing the high risk tasks, followed by the medium, then low risk tasks. To bring down vibration exposure to the lowest feasible level, NIOSH groups controls mainly under engineering and administrative work practices. PPE can also be used to reduce HAV where feasible, although it cannot effectively reduce vibration by itself.

The hierarchy of controls should be followed as much as feasible; for example, engineering controls first, administrative controls next and PPE controls last. Engineering controls on HAV are:
• Examination of alternative processes to avoid or reduce employee exposure to vibration
• Engineering the production lines to minimise the use of vibrating powered handheld tools
• Modification and redesigning by tool manufacturers of powered handheld tools to reduce vibration, such as incorporating antivibration isolators (springs) or dampening techniques

One study indicated an overall decrease of HAVS cases in England when antivibration chainsaws were introduced.

HSE cautions that although manufacturers test their equipment for vibration emission, it is important that the testing methods used are the internationally agreed upon methods such as ISO-10819. With the same testing methods, direct comparison of tool vibration emission is allowed. It is worth noting that laboratory vibration testing results may vary in actual tool field use.

NIOSH and HSE have recommended these administrative controls:
• Examination of the purchasing policy to ensure that high quality antivibration or low vibration equipment is introduced into operations
• Selection of equipment suitable and of good quality for the job; for example, use a diamond-tipped drill bit instead of tungsten-tipped bit for cutting brickwork
• Reevaluation of tasks that introduce high vibration and such tasks should be avoided when feasible or substituted with a procedure offering less vibration
• Job rotation and scheduling to limit the daily and weekly exposure time of employees
• Performance of necessary maintenance work, such as sharpening and lubrication to keep tools in top performing condition
• Reduction of grip force and pressure on the tool handle so there is just enough to keep it steady and in safe position
• Dissemination of information to the employees with risks of vibration exposure
• Implementation of a medical health surveillance programme

Mallick (2008) indicated that appropriate handheld positions of tools plus proper operating parameters resulted in reduced occurrences of HAVS in grass trimmers.

To reduce vibrations PPE should include vibration dampening materials, which are effective for high frequency vibration. Vibration dampening materials such as rubber or gel are located in either the palms or fingers of gloves and mittens, in tool handles or areas of worker tool coupling. Bjoring and Johansson (2002) concluded that gloves or handles covered with compressible rubber material decreased the total pressure level on the web between the index finger and thumb.

When working in cold temperatures, employees should be provided with warm clothing to improve blood circulation in the fingers, have regular breaks and use ergonomic aids and body posture to support the tool’s weight and pressure.

Medical surveillance

NIOSH recommends medical surveillance for employees with occupational exposure to HAV. All medical examinations and procedures are undertaken by a licensed physician with special training and experience in occupational health. A baseline or pre-placement medical examination is conducted on newly hired employees with occupational exposure to vibration.

The baseline data is compared to future results of annual medical examinations. If symptoms of HAVS are then recognised the employee should seek immediate medical attention. An employee found with Stage 2 HAVS or higher is medically removed from vibration exposure and reassigned until there is an improvement in their condition that meets Stage 1 HAVS.

Personnel training

Training must be provided to all employees who have occupational exposure to HAV - preferably within the first few months on the job. A retraining or refresher course can be required every three years. This training can be operations based training, coordinated with the company’s safety department and integrated into the tasks being performed. The topics under the training should include the nature and health effects of HAVS; occupational risk in the workplace; recognition of signs and symptoms of HAVS; medical surveillance; and controls of workplace vibration.

Recordkeeping

The latency of HAVS can be long and so records should be kept in a specified retention time, under a particular organisational unit. Records on employee medical surveillance and exposure monitoring can be kept for at least 30 years. Medical records are kept confidential, accessible only to authorised personnel.

Training records should bear the name; job title; date and duration of training; training outline; and training provider. All records on tool equipment maintenance and inspection should be kept with the employee’s department.

Programme review and evaluation

To ensure that the Vibration Safety Programme is on track, a periodic programme review and evaluation should be conducted. Annual or biennial audits can be used to gauge compliance to the planned programme activities and international or consensus standards. Benchmarking can evaluate the programme by comparing the activities of other organisations undertaking vibration programmes. If necessary, adjustments and revisions can be made on the programme based on the results of the evaluation.

Conclusion

Regular and prolonged exposure to vibration generated by powered handheld and stationary tools presents more serious risks to workers in cold climates than in warmer, more tropical areas. Vibration white finger symptoms seem to be provoked at temperatures around 15° C (59° F), meaning exposure to HAV at this ambient temperature has a higher risk of contracting VWF symptoms.

If not mitigated, excessive vibration can result in vascular and neural damage to the fingers and hands collectively; Hand Arm Vibration Syndrome, or HAVS.
In the last two decades technological advances in tool vibration dampening have significantly lowered vibration in handheld tools, yet workers can still be exposed to HAV in today’s workplace. A comprehensive programme on vibration safety can appropriately recognise, assess and mitigate hazards using a combination of engineering, administrative (including medical surveillance), and personal equipment controls.

References

Bjoring, G. & Johansson, L. May, 2002. Surface pressure in the hand when holding a drilling machine under different drilling conditions. International Journal of Industrial Ergonomics, 29(5), 255.
Futatsuka M, M Shono, H Sakakibara and PQ Quan. Hand-arm vibration syndrome among quarry workers in Vietnam. Journal of Occupational Heath, Issue 45, pp. 165-170. January 20, 2005.
Futatsuka M, T Inaoka, R Ohtsuka, T Sakurai, K Moji and T Igarashi. 1995. Hand-arm vibration in tropical rain forestry workers. Center for European Journal of Public Health, Issue 3, pp. 90-92.
Health & Safety Executive. 2005, June. Control the risks from hand-arm vibration. ISBN 978 0 7176 6117 6.
HealthLink. Raynaud’s phenomenon. Retrieved 29 Jan, 2008 from http://healthlink.mcw.edu/article/926055412.html.
Kroemer, K, Kroemer, H. & Kroemer-Elbert, K.2001. Ergonomics: How to design for ease and efficiency. New Jersey: Prentice Hall, Inc.
Mallick, Z. Jan 2008. Optimization of operating parameters for a back-pack type grass trimmer. International Journal of Industrial Ergonomics, 38(1), 101-110.
MedicineNet. Raynaud’s phenomenon. Retrieved 29 Jan 2008, from http://www.medicinenet.com/script/main/art.asp?articlekey=463&pf=3&page=1.
NIOSH. 1989. Criteria for a recommended standard: Occupational exposure to hand-arm vibration (NIOSH Publication No. 89-106). Cincinnati, OH: Author. Patient.co.uk. Hand-arm vibration syndrome (vibration white finger). Retrieved 31 Jan, 2008 from http://www.patient.co.uk/showdoc/23069104/.
Royal Society for the Prevention of Accidents. (2007, Sept.). Vibration in the workplace. Occupational Safety and Health Journal, 34-38.
State of Washington Department of Labor and Industries.WAC 296-62-051, Ergonomics.
Suzuki T and S Itoh. 1970. Relationship between ambient temperature and finger attacks. Japan Journal of Industrial Health, Vol. 12, pp. 189-191.
Yu HS, TH Yao, HM Teng, ST Ho and CT Chen. 1988. Vibration syndrome with special reference to the effects of temperature on vibration induced white finger. Journal of Dermatology, Issue 15, pp. 466-472.

Published: 27th Jun 2012 in OSA Magazine

Author


JM Glenn Batilando


JM Glenn Batilando, MS, CSP, CEES, is a safety professional serving the consumer goods, mining and transportation industries. He has a MS Occupational Safety and Health from Columbia Southern University, BS Mining Engineering from Mapua Institute of Technology, and completed OSH programmes at the University of California Davis. A Professional Member of the American Society of Safety Engineers (ASSE), he is a Certified Safety Professional (CSP), a Certified Ergonomic Evaluation Specialist (CEES), and a licensed Mining Engineer. He is currently a Safety, Health and Environment Supervisor at Unilever USA.


JM Glenn Batilando

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