For the past few weeks, I have spoken with a few clients regarding the concern over occupational exposure to vibration. So for October’s newsletter, I will be focused on the generation, evaluation and control of occupational exposure to hand-arm vibration.
Vibration: Not always fun!
We may come across vibration through our daily life, such as the one that Mrs Brown is exposed to in the following video:
However, as an OHS consultant, we focus only on vibration which is generated at workplace and which may harm you. This type of vibration includes Whole Body Vibration (WBV) and Hand-Arm Vibration (HAV). WBV enters the whole body through a vibrating floor or seat, which could happen among vehicle/heavy equipment/marine operators. HAV, which attracts most of the concern over vibration, affects the hands and arms. Hard-arm vibration is ubiquitous across the industry, which could happen among operators of chain saws, chipping tools, jackhammers, grinders and others who operate hand-held vibrating tools.
Why should vibration be of concern?
Hand-arm vibration is associated with a variety of health outcomes:
- Neurological effects. The health outcomes are progressive, which include: numbness, tingling, reduced sensory perception and dexterity.
- White finger (WF) syndrome, which refers to the attacks of whitening (i.e. blanching) of one or more fingers when exposed to cold. Vibration-induced white finger is the most common syndrome among workers using hand held tools. The development of WF syndrome is gradual, which may take several years to develop. If you take measures after the worker’s fingers have blanched, IT IS ALREADY TOO LATE!
- Raynaud’s phenomenon, which refers to a disorder of blood circulation in the fingers and toes. This condition aggravates with cold exposure. Crucial facts: 50 percent of 146 tree fellers examined in British Columbia had Raynaud’s phenomenon. 30% of 1540 forestry workers in Quebec had Raynaud’s phenomenon. After 20 years of chainsaw use, over 50% the workers had Raynaud’s phenomenon. (Resourced from Canadian Council of Occupational Health and Safety)
What are the regulations out there for HAV?
Vibration exposure can be quantified by acceleration, which is a measure of how quickly speed of vibrating object changes with time. A complete assessment of exposure to vibration requires the measurement of vibration acceleration in meters per second squared (m/s2). Vibration exposure direction is also important and is measured in a well-defined directions.
American Conference of Governmental Industrial Hygienists (ACGIH) sets up exposure limit for hand-arm vibration, which is then adopted by jurisdictions such as WorkSafeBC. The standards are summarized in the table below. It is the employer’s responsibility to ensure that the workers are not over-exposed to the limits stated below.
|Total daily exposure duration||TLV of the dominant axis, frequency-weighted, rms, component acceleration|
|4 hours and less than 8 hours||4 m/s2|
|2 hours and less than 4 hours||6 m/s2|
|1 hour and less than 2 hours||8 m/s2|
|less than 1 hour||12 m/s2|
What should I do if vibration is of concern at my workplace?
- Initiate the measurement right away. Several variables may determine the worker’s exposure to vibration, such as duration, types of tools used, worker’s posture and hand-grip force. Only through personal measurement performed following industrial standards can you assess vibration exposure and make sure that the workers are not over-exposed. Safety Solutions at Work is pleased to announce that we provide occupational hygiene services, which includes vibration measurement!
- Be aware of noise too! CCOHS suggests that there might be a correlation and combining effect between vibration and noise exposure: Since most vibrating machines and tools produce noise, a vibration-exposed worker is likely to be exposed to noise at the same time. Studies of hearing loss among lumberjacks revealed that, for equal noise exposure, those with vibration-induced white finger (VWF) had greater hearing loss than those without VWF. The reason for this effect is still unclear. Safety Solutions at Work can perform the measurement of noise and vibration at the same time, thus significantly reduces the cost of survey.
- Choose your tools wisely. If possible, choose vibration reducing hand-arm tools.
- PPE. There are vibration reducing gloves commercially available. However, it should be only used as supplemental measures, as their efficacy in reducing vibration with frequencies of highest risk of exposure is questioned.
- Keep warm. Low temperature might also contribute to the blocking of circulatory system around hand and arm and might make the VFW syndrome more severe.