The investigations were carried out to estimate the actual conditions of exposure and health of workers using impact wreches and vibrating long iron trowels (Fig. 1) in a factory producing concrete piles, and the following results were obtained: 1) Vibration acceleration levels of the impact wrenches and the trowels were in excess of the guideline of up to 30 minutes per day proposed by ISO (1979) (Figs. 3 and 4). 2) Daily amounts of time during which workers were exposed to vibration by using tools were roughly calculated to be about 60 minutes per worker. 3) As the results of the special health examinations for 35 workers, 5 cases (14.3%) were diagnosed as vibration disease, 8 cases (22.9%) were suspected of this disease, and white fingers were found in 14.3% of the workers. It was suggested that the protection from vibration and the prevention of vibration disorders are necessary for all factories such that concrete pipes or piles are manufactured by similar processes.
