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J Occup Health year 2007 volume 49 number 5 page 411 - 417
Classification Field Study
Title Mass, Number and Surface Area Concentrations of alpha-Quartz Exposures of Refractory Material Manufacturing Workers
Author Jyh-Larng CHEN1, 2, Li-Fang SU2, Ching-Lang TSAI3, Hung-Hsin LIU4, Ming-Hsiu LIN5 and Perng-Jy TSAI2, 6
Organization 1Department of Environmental Engineering and Health, Yuanpei University College of Health Science, 2Department of Environmental and Occupational Health, Medical College, National Cheng Kung University, 3Department of Earth Science, National Cheng Kung University, 4Department of Occupational Safety and Health, Chung Shan Medical University, 5Institute of Occupational Safety and Health, Council of Labor Affairs, Executive Yuan and 6Sustainable Environment Research Center, National Cheng Kung University, Taiwan
Keywords Silicosis, Quartz
Correspondence F. Talay, Department of Chest Diseases, Abant Izzet Baysal University School of Medicine, 14280 Bolu, Turkey (e-mail: ftalay2000@yahoo.com)
Abstract Mass, Number and Surface Area Concentrations of alpha-Quartz Exposures of Refractory Material Manufacturing Workers: Jyh-Larng CHEN, et al. Department of Environmental Engineering and Health, Yuanpei University College of Health Science, Taiwan-This study set out to assess the respirable mass, surface area, and number concentrations of the alpha-quartz content particles (Cr-m, Cr-s and Cr-n) to which workers were exposed in six different exposure groups, the raw material handling (n=10), crushing (n=12), mixing (n=12), forming (n=10), furnace (n=10), and packaging (n=10), in a refractory material manufacturing plant. For Cr-m, the exposure values in sequence were found as: mixing (68.1 microg/m3)>packaging (55.9 microg/m3)>raw material handling (53.3 microg/m3)>furnace (31.0 microg/m3)>crushing (29.8 microg/m3)>forming (22.4 microg/m3). We also found that ~21.2-68.2% of the above Cr-m exceeded the current TLV-TWA for the alpha-quartz content (50 microg/m3) suggesting a need for initiating control strategies immediately. We further conducted particle size-segregating samplings in four workplaces: crushing (n=3), mixing (n=3), forming (n=3), and furnace (n=3). We found that all resultant particle size distributions shared a quite similar geometric standard deviation (sigmag; =2.24-2.92), but the process area, associated with higher mechanical energy (i.e., crushing process), contained finer alpha-quartz content particles (mass median aerodynamic diameter; MMAD=3.22 microm) than those areas associated with lower mechanical energy (i.e., mixing, forming, and furnace; MMAD=6.17, 5.95, and 8.92 microm, respectively). These results gave a ratio of Cr-m in the above four exposure groups (i.e., crushing: mixing: forming: furnace=1.00: 2.30: 0.753: 1.04) which was quite different from those of Cr-s (1.00: 1.74: 0.654: 0.530) and Cr-n (1.00: 1.27: 0.572: 0.202). Our results clearly indicate the importance of measuring particle size distributions for assessing workers' free silica exposures.