A Study of Hand-arm Vibrations for the Foresters Workers

The foresters workers are especially exposed to hand-arm transmitted vibrations. These vibrations can cause the complex of vascular, neurological and musculoskeletal disorders, collectively named hand-arm vibration syndrome. Among these, the most common disorder is the vibration-induced white finger. The group exposed to vibration included: 4 hand saws cutters, 5 electric saws cutters, 3 tractor drivers and 2 truck drivers. Each worker was interviewed within health and workplace assessment questionnaires. The vibration level on the handles was measured and analyzed. The frequency-weighted acceleration, given in m/s, was calculated and the obtained values are graphically presented. The measured vibration levels are then discussed with regard to the operator's daily exposure limits recommended by the ISO 5349. The greatest vibrations occurred at 24 Hz (fundamental frequency) and at 100 and 200 Hz. All these workers have quite an experience with vibrating tools (up to 14 years) given a daily vibration exposure A(8)(10.8-13.2)(m/s). Lifetime vibration was estimated using a logarithmic scale as (19.5-21.3) (mh/s). From the obtained data, a linear dependence was determined between the logarithm from the odds of occurrence of vibration induced white finger and the exposure time. According to the exposure data of this study, the estimated regression equation indicates that the expected percentage of foresters workers affected with VWF tends to increase roughly in proportion to the square root of A(8) or in proportion to the square root of the duration of exposure.