determination and evaluation of free silica in the respiratory zone of glassworkers with x-ray diffraction method

this research was conducted from july 1993 to june 1994 on the total population (711 workers) of a glass factory. the purpose of this study was to determine the quantitative free silica (quartz) in respiratory zone of workers in glass industry. field samples including 50 samples total dust and 37 samples respirable dust and standard simplex were collected on membrane filters using skc dust sampler (niosh method). to include effects of uneven dust thickness on the filters, standard filters were prepared exactly in the same manner as the field sample have been collected, this was accomplished through the design and construction of a dust generating chamber. the analytical instrument used for quantitative and qualitative determination of free silica was an x-ray diffraction apparatus. the maximum and minimum concentration of free silica in total dust and respirable dust in the respiratory zone workers were 16:98-0.25 mg/m3, 2.55-0.1 mg/m3, respectively. the average free silica in total dust and respirable dust in the respiratory zone workers were 6.47 mg/m3 (exceeding the pel-osha by 22 times) and 0.95 mg/m3 (exceeding the tlv-twa-acgih by 9.5 times).