Sources/Uses
Any vibration in the range of 6-5000 Hz for extended period of time: pneumatic, hydraulic, electric, or internal combustion powered tools such as grinders, drills, jack hammers, riveting guns, and chain saws; Other reported causes of hand-arm vibration are brush saws, hedge trimmers, and dirt-track motorbikes; [Wald, p. 95]
Comments
Hand-arm vibration syndrome ( HAVS) is a form of Raynaud's phenomenon in which spasm of the digital arteries leads to damage to the nerves, vessels, bones, and joints of the hands and fingers. Early symptoms are blanching and cyanosis of the fingers aggravated by cold. Attacks last from 15 minutes to 2 hours and are reversible after discontinuing vibration exposure. This cumulative trauma injury occurs in workers with at least 2000 hours and usually over 8000 hours of exposure to vibration from hand tools in the range of 15-1500 Hz, but especially in the range of 125-300 Hz. [LaDou, p. 193-4] The latent interval from first exposure to onset of blanching varies from 1 month to 30 years. HAVS is classified in 4 stages from mild to very severe. From the initial episodes of blanching, the worker may later develop sensory and motor disturbances with impairment of fine motor skills, frequent attacks affecting all fingers, and finally trophic changes of the fingertips. Treatment includes cessation of smoking, keeping the body and hands warm, and avoiding vibration exposure. Prevention is key because HAVS is for the most part, irreversible. [Wald, p. 94-8]