[Investigation and evaluation on the harmfulness of partial vibration and the contact vibration time]

The harmfulness from partial vibration with extended contact vibration time was studied by investigating into the symptoms and signs of workers with local vibration disease in Taiyuan Iron & Steel Company. The sense of hand, the function of nerve ending and the microcirculation of fingernail wrinkles of 321 workers working on local vibration operations were examined and observed. The indexes examined are worse with the increase of contact time and are better in low contact group. A positive correlation between the abnormal of microcirculation, the pain and numbness of hand was observed. It is concluded that the degree of harmfulness on hands and upper limbs of whom working on local vibration operation is related to the time of contact vibration. The function of nerve ending and the ending circulation were injured at the same time.