Machines used in little olive groves: The hidden hand-arm vibration risk

Many olive groves are located in steep terrains of the Mediterranean Region, where it is not possible the use of tractors and self-propelled machines. A light mechanization is necessary to perform the olive cultivation in these areas, but unfortunately these machines are responsible of hand-arm vibrations (HAV) risks onset for the operators. This study considered two olive groves located in North Italy. Vibration data were acquired by the portable machines used in these groves (hand-tractors, chainsaws, mistblowers and beaters). The acquisition of the accelerations along the three directions (X, Y and Z) on the handles of each machine was performed in different moments during the field operations. Vibration are usually weighted using the W (ISO 5349-1 standard) weighting curve to detect the HAV risk (as requested by the European Directive, 2002/44), but this curve may underestimate the vascular risk (main cause of the Reynaud's syndrome) when frequencies are in the range 40-400 Hz. For this reason, the signals were frequency weighted using both the weighting curves W and W (ISO/TR 18570 standard). Hand-tractors, chainsaws and beaters had the highest W vibration values, but the W weighted accelerations were always very high, regardless of the machine type and model. High differences between machines of the same type were observed, to demonstrate that what it happens in field is different from the laboratory studies and from the values declared by the manufacturers.