Effects of uniformities of deposition of respirable particles on filters on determining their quartz contents by using the direct on-filter X-ray diffraction (DOF XRD) method.
In this study, field samplings were conducted in three workplaces of a foundry plant, including the molding, demolding, and bead blasting, respectively. Three respirable aerosol samplers (including a 25-mm aluminum cyclone, nylon cyclone, and IOSH cyclone) were used side-by-side to collect samples from each selected workplace. For each collected sample, the uniformity of the deposition of respirable dusts on the filter was measured and its free silica content was determined by both the DOF XRD method and NIOSH 7500 XRD method (i.e., the reference method). A same trend in measured uniformities can be found in all selected workplaces: 25-mm aluminum cyclone>nylon cyclone>IOSH cyclone. Even for samples collected by the sampler with the highest uniformity (i.e., 25-mm aluminum cyclone), the use of the DOF XRD method would lead to the measured free silica concentrations 1.15-2.89 times in magnitude higher than that of the reference method. A new filter holder should be developed with the minimum uniformity comparable to that of NIOSH 7500 XRD method (=0.78) in the future. The use of conversion factors for correcting quartz concentrations obtained from the DOF XRD method based on the measured uniformities could be suitable for the foundry industry at this stage.
Chen
Ching-Hwa
CH
Department of Environmental and Occupational Health, Medical College, National Cheng Kung University, Tainan, Taiwan.
Tsaia
Perng-Jy
PJ
Lai
Chane-Yu
CY
Peng
Ya-Lian
YL
Soo
Jhy-Charm
JC
Chen
Cheng-Yao
CY
Shih
Tung-Sheng
TS
D000336:Aerosols; D004391:Dust / Q000032:analysis; D005374:Filtration; D006801:Humans; D019570:Inhalation Exposure / Q000032:analysis*; D016273:Occupational Exposure; D011791:Quartz / Q000032:analysis*; D012822:Silicon Dioxide / Q000032:analysis; D017132:Workplace; D014961:X-Ray Diffraction
D000336:Aerosols; D004391:Dust; D011791:Quartz; D012822:Silicon Dioxide