Occupational exposure to hazardous asbestos fibers on the basis of Amercian Society for Testing and Materials criterion (length> 5mm, diameter < 3,um and length/diameter_5:1 ) were monitored in an asbestos - cement factory for the first time in the country. By evaluating personal (from worker's breathing zone) and environmental samples (from plant's atmosphere) asbestiform fibers were counted and calculated as fiber/ml (f/ml) by Phase Contrast Optical Microscope. On the basis of 8-h time weighted
average or its equivalent, average fiber levels and range of concentrations III each unit of workshops as well as, environmental concentrations were determined. The results indicated that 83.3% of workers are exposed to levels exceeding the Threshold Limit Value (TL V =0.2 F/ml) and all the studied
workshops were considered as fiber emission sources (5-13 times the TL V). Test statistic on mean with 95%. Confidence showed no significant difference between two finishing workshops, long and short pipes (? =0.05, to.975,9). In addition, 8-h daily shift duration exposures on average are less than half of that observed in the 12-h shift. Test statistic with 95% confidence showed
significant difference between mean exposure of daily shift durations (? =0.05, t095,17).
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