Long term vibration exposure may cause vibration white fingers (VWF) as well as neurophysiological disturbances such as dampness and tingling in fingers and hands, reduced grip strength and difficulties in handling small objects. In an assembly industry of heavy vehicles in Sweden a high prevalence of VWF has been reported in spite of low vibration when measuring the A(8) value according to ISO 5349. The operation that expose the workers for vibration is very similar in the production line and consists of tightening nuts and bolts with an impact wrench and an anvil in form of a wrench. Measuring vibration at frequencies up to 50 kHz shows high acceleration peaks especially in the anvil but also in the impact wrench. These high amplitude peaks are suspected to constitute a significant contribution to the high prevalence of VWF and are not taken into account in the current ISO 5349 standard which is also stated in the scope.