Vibration injury in the hand–arm system from hand-held machines is one of the most common occupational health injuries. Machines emitting high-frequency shock vibrations, e.g., impact wrenches have since long been identified as a special risk factor. In legislative and standard texts, the terms shock, impact, peak and transient vibration are frequently used to underline the special risks associated with these kinds of vibrations. Despite this fact, in the literature there is not a mathematically stringent definition of either shock vibration or how the amplitude of the shock is defined. In this study, we suggest algorithms for definition and quantification of these terms and apply them to machine vibrations of various kinds.

High-frequency shock-type vibrations (HFVs) from, e.g., impact wrenches with a frequency content mainly above 1250 Hz have long been suspected to cause a significant number of vibration injuries, HAVS. These vibrations are unregulated in the current standard for risk estimation, ISO 5349-1; thereby, the risk of injury is suspected to be underestimated. The objective of this study was to investigate the effects on finger tissue subjected to HFVs similar to those from impact wrenches by using a 2D finite element model of a fingertip. The model was validated through experiments. Using the input acceleration from the experiments, the model predicted high pressure variation and particular negative pressures at levels close to 0.1 MPa (1 Bar) or more, which are levels where cavitation in liquid can occur, with a detrimental effect on biological systems.

High-frequency shock-type vibration (HFV) with a frequency content mainly above 1250 Hz, e.g., from impact wrenches, is likely to cause a significant amount of vibration injuries and even hand-arm vibration syndrome. The objective of this study was to measure vibration up to 100 kHz with a Laser Doppler Vibrometer (LDV) and investigate the variation of vibration over the machine surface, the vibration propagation into finger tissue, and the vibration reduction on the finger tissue due to a foamed polymer layer. Our results showed that the vibration on the handle varies moderately and that the amplitudes are higher on the machine surface. A large proportion of the vibration is transferred into the finger tissue and thereby subjects the finger tissue to high-vibration amplitudes, but it is effectively reduced by a thin layer of foamed polymer.

Workers in the rock face stabilisation sector are exposed to high levels of vibration from pneumatic rock drills, which can lead to vibration injuries. The work situation is also ergonomically challenging since the work often is performed on steep cliffs with heavy equipment and a substantial degree of dust exposure. To reduce exposure to vibrations, the equipment has been redesigned, including the machine’s handle, feeding hoist and the implementation of a reciprocating mass generating a counter force to reduce the vibrations. As a side project, a dust removal device was also developed. It was shown that vibration and dust exposure can be substantially reduced.

Vibration injuries cause significant costs for society, great personal suffering, and often the relocation of personnel within a company. The project “Zero Vibration Injuries” is a Swedish initiative with the objective of taking a holistic approach to the problem, involving all stakeholders. The project’s vision is “Zero Vibration Injuries”. This is achieved by addressing the source of the problem by reducing the vibration levels in hand-held machines and applying the solutions in industry to the benefit of the users.

Background and Aims Hand-arm vibration syndrome (HAVS) is an irreversible neurodegenerative, vasospastic and musculoskeletal occupational disease of workers using powered hand tools. The etiology is poorly understood. Neurological symptoms include numbness, tingling and pain. This study examines impact hammer vibration-induced injury and recoverability of hair mechanosensory innervation. Methods Rat tails were vibrated 12?min/d for 5 wk followed by 5 wk recovery with synchronous non-vibrated controls. Nerve fibers were PGP9.5 immunostained. Lanceolate complex innervation was compared quantitatively in vibrated vs sham. Vibration peak acceleration magnitudes were characterized by frequency power spectral analysis. Results Average magnitude (2515?m/s2, rms) in kHz frequencies was 109 times that (23?m/s2) in low Hz. Percentage of hairs innervated by lanceolate complexes was 69.1% in 5wk sham and 53.4% in 5wk vib generating a denervation difference of 15.7% higher in vibration. Hair innervation was 76.9% in 5wk recovery sham and 62.0% in 5wk recovery vibration producing a denervation difference 14.9% higher in recovery vibration. Lanceolate number per complex (18.4?±?0.2) after vibration remained near sham (19.3?±?0.3), but 44.9% of lanceolate complexes were abnormal in 5 wk vibrated compared to 18.8% in sham. Interpretation The largest vibration energies are peak kHz accelerations (~?100?000?m/s2) from shock waves. The existing ISO 5349-1 standard excludes kHz vibrations, seriously underestimating vibration injury risk. The present study validates the rat-tail, impact hammer vibration as a model for investigating irreversible nerve damage. Persistence of higher denervation difference after 5-week recovery suggests repeated vibration injury destroys the capability of lanceolate nerve endings to regenerate.