Study on Effects of Shoch-Type Vibration on Peripheral Circulation in the Hand-Arm

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Altough deteriorating effects of shock-type vibration on hand-arm have been pointed out, the international standard for hand-arm vibration exposure have not provided available information on shock-type vibration. Waves produced by the normal use of chain-saw, pneumatic hammer, pneumatic riveting hammer, and pneumatic nailer at workplaces was recorded and analyzed. The order of the size in the impulsiveness, crest factor (CF) was chain-saw, pneumatic hammer, pneumatic riveting hammer, and pneumatic nailer at a constant frequency-weighted rms acceleration at x direction (a_<xhw>) of 6.3 m/s^2. No statistically significant effects of shock was recognized in comparisons of subjective response to shock-type vibration with that to shockless vibration of shain-saw. Effects of shock on peripheral circulation was examined by monitoring finger skin blood flow induced by the shock-type vibration at a constant frequency-weighted rms acceleration at x direction (a_<xhw>) of 6.3 m/s^2. In a result, pneumatic nailer with the CF of 9.5 produced significant decreases in the blood flow at 4 and 5 min after the exposure. This result suggests that effects of vibration should be assessed including the size of the impulsiveness. Experiments examining effects of hand-grasping showed significant reduction in peripheral blood flow associated with the grasping. Tools with measures which protect vibration from transmitting into hand-arm easily with the growth of grasping force should be developed in future.