Whole-body vibration: Evaluation of emission and exposure levels arising from agricultural tractors

A study was conducted to quantify whole-body vibration (WBV) emission and estimated exposure levels found upon a range of modern, state-of-the-art agricultural tractors, when operated in controlled conditions (traversing ISO ride vibration test tracks and performing selected agricultural operations) and whilst performing identical tasks during ‘on-farm’ use. The potential consequences of operator WBV exposure limitations, as prescribed by the European Physical Agents (Vibration) Directive:2002 (PA(V)D), upon tractor usage patterns were considered. Tractor WBV emission levels were found to be very dependent upon the nature of field operation performed, but largely independent of vehicle suspension system capability (due to the dominance of horizontal vibration). However, this trend was reversed during on-road transport. Few examples (∼9%) of tractor field operations approached or exceeded the PA(V)D Exposure Limit Value (ELV) during 8 h operation, but this figure increased (to 27%) during longer working days. However virtually all (∼95%) ‘on-farm’ vehicles exceeded the Exposure Action Value (EAV) during an 8-h day. The PA(V)D is not likely to restrict the operation of large, state-of-the-art tractors during an 8-h day, but will become a limitation if the working day lengthens significantly. Further ‘on-farm’ WBV data collection is required to enable creation of a robust, generic WBV emission database for agricultural tractor operations, to enable estimation of likely WBV exposure by employers.