Comparison of different measures for hand–arm vibration exposure

Vibration measurements have been done on hand-held tools in a group of 48 platers by evaluating the individual vibration acceleration and absorption of vibration energy. The measurement of the acceleration has been done frequency-weighted and frequency-unweighted in accordance with ISO 5349 and NIOSH (USA) recommendations for hand–arm vibration standards, respectively. The acceleration and the energy absorption have been measured simultaneously in the three orthogonal directions, the latter by using a specially designed adapter. The exposure time has been determined by both subjective assessments and objective measurements. Individual energy-equivalent accelerations and vibration dosages have been calculated from these data. The results show that the type of tool was critical to vibration load intensity when the different measures for determining vibration levels were used. Of the methods used, the evaluation specified by ISO 5349 makes most consideration of low frequencies of vibration (200 Hz). The results show a poor correlation between the three methods used. The same was found between mean subjective assessment and objective measurement of the average exposure time. Further studies of the relation between results presented here and generated disturbance will be conducted, which may clarify any exposure–response relationship.