Long-term Exposure Risk Assessment for Airborne Silica Dust in Ceramics Manufacturing
Date Issued
2014
Date
2014
Author(s)
Wu, Bo-Chun
Abstract
Ceramics manufacturing contains high concentration of airborne silica dust. If workers are exposed to such environments over a long period of time, they will have high risk for suffering from chronic inflammation, fibrosis, and lung cancer. In addition, silica dust concentrations vary with different manufacturing processes, resulting in working area-varied exposure risks. The purpose of this study was to assess long-term exposure risks of airborne silica dust in each working area at ceramics manufacturing. A concentration threshold for silica dust was estimated to provide a lung health warning for workers during the prolonged employment of 45 years. Based on in situ environmental monitoring data, this study quantified the silica content in the airborne dust samples and characterized particle size distributions in working areas. A physiologically based alveolar deposition models was used to estimate silica lung burden for long-term exposed workers. This study used Hill model to describe the silica dust effects on human lung inflammation and fibrosis. A Weibull threshold model was used to estimate a concentration threshold for environmental dust. This study used the probabilistic risk model to assess the health risk for workers who are exposed to silica over a long period of time for examining the degree of lung health deterioration annually. This study showed that the smallest mass median diameter was found in burning area at commodity ceramic factory of 5.64 μm. Results indicated that granulation area at tile ceramic factory had the highest silica content of 33.04% and silica dust concentration of 1246.32 ± 516.98 μg m-3, whereas the highest silica content and silica dust concentration in commodity ceramic factory was found in glazing area of 2.18% and 2.64 ± 2.84 μg m-3. Risk assessment results revealed that at risk of 0.5 for glazing workers at commodity ceramic factory during the prolonged employment of 45 years, the degrees of lung inflammation and fibrosis were mild health deterioration, whereas for those who work in granulation area at tile ceramic factory changed gradually from mild to severe. The estimated threshold value for environmental dust concentration was 361.16 μg m-3 that could be used as the monitoring reference value for environmental dust concentration in ceramics manufacturing. This study found that workers in granulation area at tile ceramic factory for a long period appeared the highest silica exposure risk, suggesting that the proprietors may monitor the environmental dust levels on a daily basis for reducing concentrations below the threshold. This study also suggests that workers with more than 15-yr seniority should initiate a periodic lung health examination program to prevent silica dust exposure-related diseases.
Subjects
陶瓷工廠
二氧化矽
氣懸粉塵
肺
暴露
發炎反應
纖維化
機率風險評估
SDGs
Type
thesis
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