Hand-arm vibration (HAV) is the vibration transmitted to a person's hand and arm when using hand-held power tools. Regular long-term exposure to excessive HAV can disrupt a person's circulation in their hand and forearm and cause damage to nerves, tendons, muscles, bones, and hand and arm joints.
It can occur when using hand-guided plant like powered lawnmowers and while holding materials being processed by plant. HAV is commonly experienced by people who use jack-hammers, chainsaws, grinders, drills, hedgers, and whipper snippers. Many local government workers – such as parks and garden workers – could be exposed to HAV in the course of their work.
Measuring vibration levels can be difficult and complex. The plant used should ideally provide vibration levels, but if not, a trained professional may be required to assess.
When workers report symptoms like tingling and numbness after using vibrating tools, the vibration levels may be reaching a level which could lead to Hand-Arm Vibration Syndrome (HAVS).
Will anti-vibration gloves minimise risk?
Finding the right hand protection is generally recommended for reducing long-term damage. Anti-vibration gloves can reduce vibration components at very high frequencies (≥500Hz), especially when a low hand coupling force is applied.
Gloves may be suitable for some types of hand-held plant, but the gloves' exposure range and axis need to be assessed against the vibration.
ANSI/ISO standard anti-vibration gloves require:
- Full-fingered design
- Uninterrupted palm pad from base to fingertips
- Padding ≤ 8mm thick in the palm and ≥ 0.55 times the palm padding thickness in the fingers and thumb
- Reduction of "medium range frequencies" (TM) by ≥ 10% vs. bare hand
- Reduction of "high range frequencies" (TH) by ≥ 40% vs. bare hand
The major risk associated with the use of anti-vibration gloves is that they can give a false sense of protection against the negative effects of hand-transmitted vibration. There are also concerns over meeting the requirements of ISO 10819 // ANSI S2.73 (the international standards). Many gloves may not have been third-party tested, while even those that have been may not be adequate due to limitations in the current standards regarding testing and certification.
This all raises questions regarding the extent of protection that anti-vibration gloves provide against HAVS. It's important to consider both the benefits and potential drawbacks on a case-by-case basis.
LGIS would not recommend the gloves as a suitable control for sustained exposure to vibration, and instead recommend other preventative controls should be implemented, so far as is reasonably practicable.
How to limit exposure?
First steps in limiting exposure could include assessing the amplitude of the vibration in plant used and utilising those with the lowest output, as well as reducing total exposure time.
The following steps can help ensure control measures are in place to limit exposure to HAV in the workplace:
- Identify potential vibration hazards
- Assess the risks – consider the likelihood of someone being harmed by the hazard and how serious the harm could be.
- Take action to control the risk
- Provide information, instruction, and training to workers
- Check control measures regularly
If you experience tingling or numbness when using vibrational plant, you should make note of how long you can safely use the plant, then stop using it two-five minutes prior to that threshold. Workers should also complete preventative exercises to improve blood flow and encourage movement.