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KMID : 0381319940330040153
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Korean Journal of Occupational Health
1994 Volume.33 No. 4 p.153 ~ p.162
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Exposure Concentrations of Respirable Coal Dust and Silica Contents by Work Processes in Coal Mines
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Abstract
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This survey was designed to investigate the concentrations of respirable coal dust and the silica content in respirable coal dust samples by work processes and other environmental factros in the coal mining industry.
Respirable coal dust samples were collected from 5 coal mines utilizing NIOSH methods 7602 during the period from July 7th to July 29th, 1992. Silica contents were determined by Fourier Transform Infrared Spectrophotometry.
The results were as follows :
1. The geometric means(standard deviation) were 3.97(2.87) mg /㎥ in picking work, 7.28(4.35) mg /㎥ in caving work of coal face, 0.60(2.20) mg /㎥ in drilling work, 0.63(3.49) mg /㎥ in carring work, 1.78(5.88) mg /㎥ in coal chuting and 3.27 (3.72) mg /㎥ in separating work. Although being measured at the same coal face, the concentrations of respirable dust significantly higher in caving work than in coal picking work.
2. The geometric means of silica contents in respirable dust were significantly higher in drilling work(7.32%) than in coal face(1.98%) and in separating work(3.04%). This results implies that drilling workers would be more susceptible to contracting silicosis than other workers.
3. The means of CO and CO₂ concentration after explosion were 98 ppm and 8,159 ppm in coal face, and 200 ppm, and 11,200 ppm in drilling work. However, those before explosion were 1.8 ppm and 2,175 ppm in coal face, and 12 ppm, and 2.118 ppm in drilling work.
4. Noise levels measured near auger drill, drilling machine and separating work at coal face were 106 dB(A). 110 dB(A) and 111 dB(A), respectively.
5. Mean air velocities at coal face, drilling and transportation way were markedly lower than those of OSHA recommended standard (0.15 m /sec), accounting for 0.07 m / sec, 0.09 m /sec and 0.1 m /sec. respectively.
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