This study was conducted to estimate crystalline silica contents in airborne respirable dust from various manufacturing industries and to compare analytical performance of two methods of quantifying crystalline silica, X-ray diffraction(XRD) and Fourie transform infrared spectroscopy (FTIR). For this study, various manufacturing industries with a history of having pneumoconiosis cases and also known to generate dusts containing crystalline silica were investigated. These industries include: foundry, brick, potteries, concrete, and abrasive material, etc. Both personal and area respirable dust samples were collected using 10㎜, Dorr-Oliver nylon cyclone equipped with 37㎜, 5㎛ pore size, polyvinylchloride(PVC) filters as collection media. In addition, total dust samples were collected side-by-side to the respirable samples. All samples were weighed before and after sampling and were pretreated according to the NIOSH sampling and analytical methods 0500, 7500, and 7602 for dust collection and quartz analysis. In addition, bulk samples were collected and analyzed by X-ray fluorescence (XRF) for minerals.
In this article, only the results obtained from foundry are reported. The results from various other industries will be published in future articles. The respirable dust concentrations from personal samples by cyclone were 0.46-1.06㎎/㎥ and those from area samples were 0.34-0.73㎎/㎥. Dust concentrations of personal samples were significantly higher than those of area samples. The highest dust concentration was obtained from the personal samples of the finishing operation. Total dust concentration ranged 1.24-3.40㎎/㎥. The mean quartz contents estimated by FTIR and XRD in the personal respirable duet samples were 5.12 % and 4.41 %, respectively, without significant difference between them. For quartz analyses, the two techniques were highly correlated with r² ranged 0.803-0.920. But the results by FTIR were mostly higher than those by XRD. In addition, cristobalite was not detected by FTIR. Significant correlations between contents of crystalline silica and such minerals as A1₂O₃, CaO, TiO₂, and K₂O suggest possible interferences from these minerals.
|