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Bad Vibrations

Published: 11th Nov 2016

Our hands are one of our primary points of interaction with the world around us. We cook and clean with them, we write and eat with them, we say hello and hold our loved ones with them.

The frustrating irony is that this amazing tool we possess also is a part of our bodies most susceptible to injuries, and these injuries happen too frequently, particularly in the workplace.

Incurring hand and arm injuries can pose devastating consequences for workers for a variety of reasons. If the injury is severe enough that they lose function or worse yet, lose a limb, their future employment could be at risk. Not only that, but losing upper extremities means workers can’t engage in the off-work activities they once found fulfilling and enjoyable.

With care though, hand and arm injuries easily can be avoided. Following established safety guidelines and using protective guards, shields, gloves and other protective devices as needed not only can save a worker’s hands from injury, but can save workers a lot of emotional frustration and their employers unnecessary disability claims.

Types of injuries

Aside from the head, hands and arms are the most exposed parts of the body and can fall victim to a laundry list of injuries, such as:

  1. Traumatic injuries - Hands, fingers and arms can get caught, pinched, crushed and amputated in chains, wheels, rollers, gears or other types of machinery. They can be punctured, torn or cut by spiked or jagged tools and edges that shear or chop.
  2. Contact injuries - Hands and arms are injured through contact with solvents, acids, cleaning solutions, flammable liquids and other substances that can cause burns or injure tissue.
  3. Repetitive motion or musculoskeletal injuries - Hands and arms become injured when tasks require repeated, rapid hand movements for long periods of time, resulting in strains and sprains of the upper extremities.

For the purpose of this article, however, we shall be focusing on the condition often known as hand-arm vibration syndrome or HAVS.

What is hand-arm vibration?

HAVS is vibration transmitted into workers hands and arms. It can come from use of hand-held power tools, such as grinders or road breakers; hand-guided equipment, such as powered lawnmowers or pedestrian controlled floor saws; or from holding materials being worked by hand-fed machines, such as pedestal grinders or forge hammers.

Why is hand-arm vibration an issue?

Regular and frequent exposure to hand-arm vibration can lead to two forms of permanent ill-health known as:

  • Hand-arm vibration syndrome (HAVS)
  • Carpal tunnel syndrome (CTS)

Symptoms and effects of HAVS include:

  • Tingling and numbness in the fingers which can result in an ability to do fine work such as assembling small components; or everyday tasks such as fastening buttons
  • Loss of strength in the hands which might affect the ability to do work safely
  • The fingers going white (blanching) and becoming red and painful on recovery, reducing the ability to work in cold or damp conditions, e.g. outdoors

Symptoms and effects of CTS can also occur and include:

  • Tingling, numbness, pain and weakness in the hand which can interfere with work and everyday tasks and might affect the ability to do work safely.

Symptoms of both may come and go, but with continued exposure to vibration they may become prolonged or permanent and cause pain, distress and sleep disturbance, which in turn causes fatigue at work.

This can happen after only a few months of exposure, but in most cases it will happen over a few years.

Preventing disability

The main principle of prevention is to reduce the risks from vibration to the lowest level reasonably practicable and to reduce exposure to as low as reasonably practicable.

Some people will develop early signs and symptoms of HAVS or CTS even at low exposures (for example, if they are susceptible to vibration injury and are regularly exposed to vibration, usually for some years). Your health surveillance should identify any harm early on, so appropriate action by you at this point will prevent disability.

It is important that you consult your employee representative on your proposals to:

  1. Control risk
  2. Provide health surveillance

Certain cases of HAVS and all cases of vibration related CTS may need to be reported to your local authorities in accordance with local regulations.

Is hand-arm vibration a problem in my workplace?

In some industries, assessment will often show that the operating time of the equipment is actually very short and that the exposure action value (EAV) is not exceeded.

Which jobs are most likely to create a risk?

Jobs involving regular and frequent exposure to vibration above the EAV are found in a wide variety of industries, for example:

  • Construction and civil work
  • Engineering
  • Forestry
  • Foundries
  • Motor vehicle manufacture and repair
  • Maintenance of parks, gardens, verges, grounds etc.
  • Shipbuilding and ship repair
  • Utilities (e.g. gas, water, telecommunications)

Which tools are most likely to create a risk?

Users of the types of equipment listed below and similar equipment will often be exposed above the EAV:

  • Chainsaws
  • Grinders (all types and sizes, e.g. angle, die, straight, vertical etc.)
  • Hand-fed equipment, e.g. pedestal finishers, grinders, mops
  • Impact drills
  • Scaling hammers including needle scalers
  • Pedestrian controlled equipment including mowers, floor saws, floor polishers
  • Powered hammers for chipping, demolition, road breaking etc.
  • Sanders and polishers
  • Hand-held saws for concrete, metal, ground clearance etc.

Damaged and very old models of equipment may be hazardous even when used for short periods. Most types of hand-held, hand-guided or hand-fed powered equipment can cause ill heath from vibration if used incorrectly.

For powered hand-tools, regular and frequent use of modern, well-designed, well-maintained tools is likely to result in exposure at or above the EAV after:

  • The use of a hammer action tool for about 15 minutes; or
  • Use of non-hammer action tools for about four hours

How can I control the risks from HAVS?

You can reduce the vibration exposure by reducing one or both of:

  • The vibration transmitted to the hand; and
  • The time spent holding vibrating equipment, or work pieces

Does PPE help?

Anti-Oration gloves are a hot topic in industrial safety, but the development of the industry surrounding it has been around since the symptoms of HAVS were first diagnosed in 1911.

As explained above, the regular exposure to vibration often leads to the incurable, irreversible HAVS, originally called Raynauds Phenomenon or Vibration White Finger.

Anti-vibration gloves aim to absorb and dampen the vibrations emitted by these tools that can affect the central nervous system long term. There are several variations of these gloves on the market today that use different methods of reducing sonic repetitive injury, ranging from simple foam padding to air pockets and gels. The effectiveness of these materials varies by glove manufacturer as much as it does by material.

In an effort to protect workers on job sites around the world and create a uniform playing field, the PPE industry has made inroads in developing a suitable vibration-reducing glove testing standard that measures a glove’s ability to help dampen a portion of the vibrations unavoidably transmitted by impact and power tools. The ANSI S2.73/ISO 10819 tests have been both a blessing and a curse to both the manufacturing and end user sides.

Changes in the Anti-Vibration Glove Testing Standard: ISO 10819 in 2013 were not highly publicised and made adjustments to the way the handle and adapter readings were calibrated and measured from the original 1996 standard. ISO 10819 aims to gauge the vibration transmissibility of a glove with a vibration-reducing material that covers the palm, fingers, and thumb of the hand.

The basic setup of this test involves a person wearing a glove gripping a vibrating handle with load cells to gauge the transmissibility of the vibrations through the glove. An “anti-vibration glove” must not amplify the vibration in the medium frequency range (1.5Hz to 200Hz); in the high frequency range (200Hz to 1250 Hz), the glove must reduce the frequency weighted vibration by at least 40 percent.

The most accurate method to determine the actual vibration magnitude exposure of workers is to perform on-site vibration analysis, which can vary significantly from the values declared by the tool manufacturers. In-use vibration, where the operator is using a tool in a real work situation in a specific workplace, depends not only on the vibration produced by the tool, but also on many other variables, such as the condition and quality of the inserted tool, type of product, the state of maintenance of the power tool, the design of the process, the worker’s posture and technique, etc. Multiple tests should be performed accounting for all variables, and an average of these tests should be used as the vibration value.

In an independent study funded by the US Navy, researchers found that while many gloves submitted for testing passed the vibration transmissibility criteria specified by the standard, none of them could be classified as an AV glove because none of the gloves could meet the standard’s criterion for the thickness of the glove fingers.

Applications where workers must maintain a steady grip on a potentially dangerous power tool are relatively ignored by the standard that requires gloves to maintain a uniform thickness of vibration-dampening material between the thumb and finger as in the palm. The resultant lack of dexterity has many glove makers scratching their heads.

Safety managers know that flexible, ergonomic gloves reduce hand strain, and industrial accidents directly related to hand strain and hand fatigue can often have serious consequences. Many injuries occur towards the end of the shifts, when workers let their guard down. Add fatigue and muscle strain, and you see the severity of incidents spike. Fatigue is a difficult thing to measure, but the consequences of repetitive injuries make a noticeable impact.

Assessing likely risks

The industry, type of equipment, duration of use and reported signs or symptoms of HAVS or CTS are all good guides to the likelihood of vibration risk. Once you have established the likelihood of risk you should look more closely at which workers, or groups of workers, are likely to be at risk and what can be done to reduce those risks.

Assess who is at risk

You should:

  • Carry out a brief survey of the workplace. Find out who is exposed to hand-arm vibration and what is causing the exposure
  • Estimate the time workers spend holding the equipment or work-piece while it is vibrating. Begin to set priorities:
  • Very short periods may not be a problem; but
  • The longer the equipment or work-piece is held the higher the exposure will be so it is more important that the vibration is low
  • Ask users of equipment if they feel tingling or numbness during or after exposure to vibration. If they do, their exposure to vibration could be causing them harm

Use the guidelines above to determine when users of powered hand-tools are likely to reach the EAV and if there could be a risk.

You should find out if any of your employees already have HAVS or CTS. If they do, you will need to take steps to stop their symptoms getting worse, even if they are exposed below the EAV.

How should I use this information?

Having decided that employees have vibration exposures which must be managed, you will need to look at how risks from vibration can be reduced, finalise your priorities and put in place those steps that are reasonably practicable. You should:

  • Look for ways of working that avoid or reduce the need to hold vibrating equipment of work-places
  • Consider vibration emissions when purchasing or hiring equipment, for example:
  • Check the vibration of available equipment in technical sales literature or the handbook
  • Avoid types with high vibration when there are suitable lower vibration alternatives
  • Keep an inventory of equipment and its vibration emission
  • Maintain equipment in accordance with the manufacturer’s instructions
  • Plan work schedules to minimise vibration exposures and make sure exposures are below the ELV
  • Organise work and design workstations to avoid uncomfortable postures and the need for high manual effort to grip, push or pull equipment
  • Help employees maintain good blood circulation, for example, by providing clothing to help them keep warm and dry

Information, instruction and training

Your information, instruction and training for employees should cover:

  • The health effects of hand-arm vibration
  • The sources of hand-arm vibration and how the vibration has been minimised, e.g. the choice of process or equipment
  • Whether they are at risk, including how their exposure compares with the exposure action and limit values
  • How to recognise and report symptoms
  • How health surveillance can help them remain at work and what your arrangements are for health surveillance (see below)
  • The steps you have taken, or plan to take, to minimise the risk
  • Where necessary, training in how to use equipment to minimise vibration and how to reduce grip force etc.

Health surveillance

Health surveillance can involve just a short set of questions until, for example, signs or symptoms are reported. A health surveillance scheme must include access to a competent occupational physician. Make sure that your providers have the right qualifications and training and that you will:

  • Receive feedback, including notification of fitness for work with HAV for each employee under health surveillance
  • Receive anonymised health surveillance results (unless groups of employees are too small to get this type of information)
  • Be informed of new or deteriorating cases of HAVS that are being diagnosed (with the consent of the affected person)

Prompt action by you to revise your controls - when finding new cases or worsening of existing cases - will help keep skilled people in work and should prevent disability.

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Toby Hayward
Mr. Hayward has worked in various high-risk industries including nuclear, offshore and deep sea. Having also been a corporate leader of health and safety in international companies he has spent more than 20 years advocating for sensible risk culture both in the Middle East and Globally