Study of the vibrations produced by portable shakers during olive harvesting

Vibration exposure of agricultural workers is one of the most important topics concerning safety and comfort. The problem is exacerbated by the increase in mechanisation level of many activities recognised in the last decades and may regard both the whole body and the hand-arm system. The transmission of the vibrations through the hand-arm system is consequent to the use of vibrating tools equipped with handles; it is a rather complex phenomenon because involves several factors which interact with the intensity of the vibration and its way of introduction and propagation in the organism. This paper deals with the vibration levels produced by portable shakers and transmitted to the operators through the hand-arm system. These types of tools are widely used in olive orchards for the harvesting operations, essentially due to their relatively low purchase price and low maintenance costs and when the traditional tractor-mounted or self-moved shakers can’t be used. Experimental tests have been carried out in different olive orchards located in Apulia and Sicily (Southern Italy) using brand new models of portable shakers, chosen among the ones available on the market, equipped both with internal combustion engines and electrical engines. During the tests, the machines were always driven, by workers experienced in their use. Measurements were carried out according to the standard UNI EN ISO 5349-2, using suitable tri-axial accelerometers and a data acquisition system made by a PC and a multi-analysis real-time interface. Assuming a daily exposure time equal to 4.5 h, the results showed A(8) values ranging from 10 to 17 m s-2, much higher than the action (2.5 m s-2) and limit (5.0 m s-2) threshold values established by the Italian regulation 81/08. Even taking into account the peculiarity of the working conditions in agriculture with respect to the industrial environment, the high values of acceleration suggest the adoption of shifts among two or three workers during the work-day. Furthermore, it is fundamental to inform the operators about health risks and safety precautions that need to take into account to reduce continuous vibration exposures over long periods.