Coupling force-adjusted hand-arm vibration exposure and its long-term associated hazard assessment concerning musculoskeletal disorders - methodological comparisons.

When holding or carrying vibrating machines, the coupling forces play a major role in transmitting the vibrations to the hand-arm system. In an epidemiologic study, two recommended methods from ISO/TS 15230-2 are used to investigate the relationship between coupling force-adjusted vibration exposures and their related risk of musculoskeletal disorders of the upper limb. Therefore, coupling forces have been professionally estimated for 408 machines used by 683 male participants during their entire working life and coupling force-adjusted long-term vibration doses are calculated. Despite different approaches of the two methods, overall lower dose values are correlated to the risk of musculoskeletal disorders if the coupling force was adjusted. Considering the 10% increased risk of musculoskeletal disorders, the original cumulative vibration doses of 19571 m²/s⁴ fell to 15995 m²/s⁴ and 18119 m²/s⁴ according to two different coupling force-adjusted doses. These results show the necessity of consideration of coupling forces, especially for on-body measurements.